The Role of Eclipses and European Observers in the Development of ‘Modern Astronomy’ in Thailand

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Orchiston, W., Sule, A., and Vahia, M.N. (eds.), 2018. Growth and Development of Astronomy and Astrophysics in India
and the Asia-Pacific Region. Proceedings of the 9th International Conference on Oriental Astronomy. Mumbai, Tata
Institute of Fundamental Research. Pp. 97‒122.
Page 97
THE ROLE OF ECLIPSES AND EUROPEAN OBSERVERS IN THE
DEVELOPMENT OF ‘MODERN ASTRONOMY’ IN THAILAND
Wayne Orchiston, Darunee Lingling Orchiston, Martin George
Astrophysics Group, University of Southern Queensland, Toowoomba,
Queensland 4350, Australia.
Emails: wayne.orchison@gmail.com; needa6565@gmail.com;
martingeorge3@hotmail.com
Boonrucksar Soonthornthum
National Astronomical Research Institute of Thailand, 260 Moo 4,
T. Donkaew, A. Maerim, Chiang Mai 50180, Thailand.
Email: boonrucksar@narit.or.th
Lars Gislén
Lund University, Dala 7163, 24297 Hörby, Sweden.
Email: LarsG@vasterstad.se
Suzanne Débarbat and Matthieu Husson
LERMA, Observatoire de Paris, 61 avenue de l’Observatoire,
F-75014 Paris, France.
Emails: suzanne.debarbat@obspm.fr
matthieu.husson@obspm.fr
Abstract: ‗Modern astronomy‘ was introduced to Siam (present-day Thailand)1 when the Belgian Jesuit missionary-
astronomer Father Antoine Thomas carried out stellar and lunar eclipse observations during 1681 and 1682 in order
to determine the latitude and longitude of Ayutthaya. Three years later a contingent of French Jesuit missionary
astronomers observed a total lunar eclipse from Lop Buri, which marked the start of an intensive two-and-a-half year
period of observational activity at Lop Buri under the sponsorship of King Narai. During this interval, a partial solar
eclipse and two further lunar eclipses were observed from a number of different observing sites. Although a
substantial astronomical observatory was constructed in Lop Buri and this was used by French Jesuit missionary-
astronomers, ‗modern astronomy‘ ended suddenly in 1688 when King Narai died and most Western missionary-
astronomers were expelled from Siam.
‗Modern astronomy‘ only re-emerged in Siam after a hiatus of almost two hundred years when another royal
supporter of astronomy, King Rama IV, invited French astronomers to observe the total solar eclipse of 18 August
1868 from Siam, and his son, King Rama V, hosted British astronomers during the 6 April 1875 total solar eclipse.
Thailand‘s romance with total solar eclipses continued during the 9 May 1929 solar eclipse when King Rama VII
visited British and German astronomers based near Siam‘s southern border, and this was the catalyst required for
the birth of home-grown ‗modern astronomy‘. Soon after, Siam‘s first astronomy classes began at Chulalongkorn
University, and in 1944 this university hosted Siam‘s first professional astronomer when Rawee Bhavilai, a solar
specialist, joined the Physics Department. The latest phase in the professionalisation of astronomy occurred in 2009
when the Government approval the formation of the National Astronomical Research Institute of Thailand (NARIT).
In this paper we trace the critical roles that solar and lunar eclipses played in the emergence and final adoption of
‗modern astronomy‘ in Thailand from 1682 through to the present day.
1 INTRODUCTION
This paper deals with the development of mod-
ern astronomy in Siam (which is now known as
Thailand). By ‗modern astronomy‘ we refer to
Western astronomy, as it was practised by train-
ed astronomers in Europe during the seventeenth
to twentieth centuries, and the emergence of sol-
ar physics and astrophysics in Thailand and other
Asian nations in the eighteenth and nineteenth
centuries (see Nakamura and Orchiston, 2017).
An underlying theme throughout the past four
hundred years has been the key role that solar
and lunar eclipses played in the birth and ultimate
adoption of Western astronomy in Asian count-
ries. Initially, eclipse observations were used to
determine the longitudes of the observing sites.
For example,
In the 17th and partly also in the 18th century
Hipparchos‘s old method for the determina-
tion of longitudes was renovated using the
transits of craters on the edge of the shadow
... Though the accuracy of this method could
not exceed more than some tenth of a minute
of time, its utility was great in those times. For
instance the eclipse of 1634 observed in
Cairo, Aleppo and the western part of Eu-
rope, enabled the astronomers to shorten the
Mediterranean Sea by 1000 km in respect to
its assumed length before that time ... (Link,
1959: 10).

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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Figure 1: King Narai (en.wikipedia.org).
Then, during the second half of the nineteenth
century, solar eclipse observations led to major
breakthroughs in solar physics, and especially
our knowledge of the solar corona (e.g. see
Clerke, 1893; Meadows, 1970; Nath, 2013).
In this paper we review lunar and solar
eclipses observed from Siam in 1682, 1685, 1686
and 1888, and Siamese observations of the total
solar eclipses of 18 August 1868, 6 April 1875
and 9 May 1929. For each eclipse we describe
the astronomers involved, their scientific instru-
ments and their observations. We end this paper
by briefly noting the development of professional
astronomy at a Thai university in the 1930s, and
the founding of the National Astronomical Re-
search Institute of Thailand in the early years of
the twenty-first century.
2 THE ECLIPSES
2.1 Introduction
The appearance of ‗modern astronomy‘ in Siam
was made possible only because of the person-
al interest of King Narai. One of the most rever-
Table 1: Thai kingdoms and dynasties. King Narai ruled
during the Prasat Dynasty.
Kingdom
Duration
(years AD)
Dynasty
Sukhothai
1238–1438
Ayutthaya
1350–1767
Uthong
Suphannaphum
Sukhothai
Prasat
Ban Phlu Luang
Thonburi
1767–1782
Rattanakosin/Thailand
1782–
ed of Thailand‘s historic rulers, King Narai the
Great (Figure 1; see Orchiston et al., 2016) was
born in 1633 and died prematurely in July
1688. Narai was the fourth king to rule during
the Prasat Dynasty, which was the fourth of the
five dynasties of the Ayutthaya Kingdom (see
Table 1). He was just 23 years of age when he
became the King of Ayutthaya, in 1656, and
ruled until his death.
Two years before his death, King Narai was
described by a visiting Westerner:
[He is] … about 55 years old, handsome, lovely,
dark, has good behaviour, and is brave. He
is also intelligent, a good ruler … [and is] kind-
hearted … (Chaumont, 1686).
Unfortunately there are no other descriptions of
King Narai and we cannot be sure that the like-
ness shown in Figure 1 is realistic, as not long
before the visit that prompted this portrait he had
entertained a Persian delegation, and he liked
their attire so much that he decided to adopt it for
his own court appearances (Smithies and Bres-
sen, 2001).
When he became king, Narai
…. inherited a large and powerful kingdom in
the centre of mainland South-East Asia. His
realm reached south to the kingdoms of
Pattani, Ligor, Phattalung and Songkhla; in the
east Cambodia had acknowledged Ayuttaya‘s
suzerainty, and in the west the port of Ten-
asserim on the Bay of Bengal was under Thai
control. (Hodges, 1999: 36).
For Thai localities mentioned in this paper see
Figure 2.
King Narai had an enlightened foreign policy.
He believed that exposure to Eastern and West-
ern civilizations was a good way of developing
Siam, so during his reign he signed treaties with
England, France, Holland and Persia, and he ex-
panded trade with India, Indonesia, China and
Japan. Soon Ayutthaya, the Siamese capital,
gained a ―… reputation as an ‗emporium of the
East‘ ...‖ due to its role ―... as a focus for the trans-
shipment of goods between Europe/India and
China/Japan ...‖ (Sternstein, 1965: 108).
Because of King Narai‘s
… enlightened policy of promoting increasing
contact with Eastern and Western nations,
both Lop Buri and Ayutthaya quickly acquired
a cosmopolitan flavour, with Armenian, Chin-
ese, Dutch, English, French, Indian, Japanese,
Javanese, Malay, Persian, Portuguese and
Turkish communities. Many of these people
worked for the state or had their own busi-
nesses, but there was always a transient pop-
ulation of visiting Europeans, Arabs, Indians
and Asians. Because of this, there is a wealth
of published material on seventeenth century
Siam, as book after book appeared describing
—and often singing the praises of—Ayutthaya
and Lop Buri. It must be remembered that by

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 99
international standards both were large cos-
mopolitan cities. (Orchiston et al., 2016: 28).
One of King Narai‘s personal interests was
astronomy. As a prince, he received a thorough
Buddhist education from the monks, but he also
was taught astrology and astronomy by lay teach-
ers. Once he was king, Narai‘s contact with for-
eigners also contributed to his education, for as
Hodges (1999: 36) has pointed out,
His reign coincided with European advances
in the sciences associated with navigation,
astronomy and horology. He lived in an age
when humans were first beginning to grasp the
nature and extent of the cosmos ...
At this time there was a constant stream of Jes-
uits and other Europeans passing through Siam
en route to China or returning to Europe (e.g.
see Love, 1999; Vande Walle and Golvers, 2003),
and through them King Narai continued to learn
about astronomy, telescopes, other scientific in-
struments and the newly constructed Paris Ob-
servatory. Furthermore, instead of favouring gifts
of cloth, spices and jewellery typically presented
by visiting dignitaries, King Narai made it known
that he also liked to receive telescopes, clocks
and military equipment (Hodges, 1999).
This was the scientific-cultural milieu in Siam
when it gained its first exposure to ‗modern‘ West-
ern astronomy in 1681.
2.2 The Lunar Eclipse of 22 February 1682
In Table 2 we list the start, middle and end times
of the total phase of the lunar eclipse in local
time,2 along with the positions of the Moon and
Sun, as observed from Ayutthaya. As the table
illustrates, this eclipse was visible in the morning
just before the beginning of astronomical twi-
light, and the Moon was low in the western sky.
Sunrise occurred at 06h 39m local time, before
the eclipse had ended, so only the very early parts
of totality were visible in a completely dark sky.
Mid-totality occurred just before the beginning of
civil twilight. By this time, the sky would have
had an obvious blue hue, with only the brighter
stars still visible.
2.2.1 Father Antoine Thomas: The Observer of
the Eclipse
The Jesuits were an order of Roman Catholics
with particular interest in astronomy and mathe-
matics (see Udias, 2003) and during the sixteen-
th century the Spaniard Francis Xavier founded
Jesuit missions throughout Asia. Thus, when
King Narai assumed the throne in 1656 ―... there
were Jesuits as well as Dominicans [already]
established in the Portuguese colony at Ayŭt‘ĭa.‖
(Hutchinson, 1933: 6).
Despite this early Jesuit presence in Siam
during King Naria‘s reign it was only in 1681
that the missionary-astronomer Father Antoine
Figure 2: A map showing Thailand localities mentioned in
the text (map: Wayne Orchiston).
Thomas took up temporary residence in Ayut-
thaya, and as far as we have been able to
ascertain he was the first to introduce Siam to
Western astronomy (Orchiston et al., 2018a).
Antoine Thomas was born in Namur (Bel-
gium) on 25 January 1644, and joined the Jesuit
Order in 1660. While training for the priesthood
he studied in various towns in Belgium and in
France (Lefebvre, 1930), and by the time he
was ordained, in 1678, he had developed an
interest in mathematics and astronomy. Sub-
sequently he studied mathematics in Portugal
and published a short research paper (Thomas,
1679) about a lunar eclipse that he observed.
Thomas planned to carry out missionary work
in Japan, and while trying to arrange this he had
to spend nearly a year in Siam. By good for-
tune, the 22 February 1682 lunar eclipse occur-
red during this sojourn.
Table 2: Details of the lunar eclipse 22 February 1682.
Totality
Local
Time
Moon
Altitude Azimuth
Sun
Altitude Azimuth
Start
05h 25m
+17° 267°
–19° 96°
Middle
06h 13m
+06° 279°
–07° 99°
End
07h 01m
–05° 282°
+05° 102°

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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Figure 3: A map of Ayutthaya in the 1680s showing the location of the Portuguese residential precinct (marked ‗Portugals‘ to the
south of the river on the left), and above the Malayan precinct. The Portuguese Jesuit church was on the western bank of the river
close to the bottom of the map, and is marked by the ‗I‘ (after Loubère, 1693).
2.2.2 Father Thomas‘ Observations of the
Eclipse
Soon after he settled in the Portuguese sector of
Ayutthaya Father Thomas carried out solar ob-
servations in order to determine the latitude of
the city. These observations were made from
―… the House of the Society of Jesus in the sub-
urbs, to the south of Juthia [i.e. Ayutthaya].‖
(Thomas, 1692; our English translation).
Father Thomas records (1692) that he observ-
ed the 22 February 1682 eclipse, but Bhumad-
hon (2000) suggests that his observations were
made in collaboration with Father Gouye. How-
ever, Gouye‘s account (1692: 693) clearly docu-
ments that it was only Thomas who made the
observations. As we suggested earlier,
The confusion appears to have arisen be-
cause even though Gouye was tasked with
publishing the astronomical observations of
the Jesuit missionary-astronomers who were
based in Siam, he also liked to add his own
comments and corrections. However, Gouye‘s
Table 3: Details of the lunar eclipse of 11 December 1685.
Totality
Local
Time
Moon
Altitude Azimuith
Sun
Altitude Azimuth
Start
04h 37m
+26° 288°
–27° 109°
Middle
05h 29m
+15° 290°
–15° 110°
End
06h 21m
+03° 293°
–04° 113°
biography (see Thomas Gouye, n.d.) clearly
indicates that he spent his whole life in
France and never visited Siam (Orchiston et
al., 2016: 42).
Unfortunately, we do not know from exactly
where Father Thomas observed the eclipse.
It would have been from the Jesuit church in
the Portuguese district of Ayutthaya or from the
ver-anda or courtyard of the Jesuit residence
which was located near the church. The
location of the Jesuit church is shown on several
old maps of Ayutthaya, and one of these is
reproduced here as Figure 3.
Father Thomas (1692) makes no mention of
having access to a telescope, so we can pre-
sume that he observed the eclipse with the
naked eye, but to record the contact times we
know that he used a simple pendulum clock
(ibid.).
For further information about Father Antoine
Thomas and his observation of the 1682 lunar
eclipse see Orchiston et al. (2018a).
2.3 The Lunar Eclipse of 11 December 1685
In Table 3 we list the start, middle and end
times of the total phase of this lunar eclipse in
local time based upon modern calculations, along
with the positions of the Moon and Sun, as ob-

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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Table 4: Jesuit missionary-astronomers who came to Siam in 1685 with the French delegation.3
Name
Birth/Death Dates
Immediate Destination after Siam
Jean de Fontaney
1643–1710
China (1688–1702)
Joachim Bouvet
1656–1730
China (1688–1697; 1699–1730)
Louis le Comte
1655–1728
China (1688–691)
Jean-François Gerbillon
1654–1707
China (1688–1707
Guy Tachard
1648–1712
Remained in Siam
Claude de Visdelou
1656–1737
China (1688–1709); India (1709–1737)
served from Lop Buri. As the table illustrates,
the eclipse of 10‒11 December 1685 was visible
from Siam on the morning of 11 December, with
the start of totality occurring before the begin-
ning of astronomical twilight. At this time, the
Moon was about 20° north of due west and was
low in the sky. Astronomical twilight would have
just begun when the eclipse reached the mid-
totality phase, and there would have been a minor
twilight glow on the horizon about 20° south of
east.
2.3.1 The French Jesuit Contingent to Siam:
Observers of the Eclipse
This eclipse was observed by a group of French
Jesuit missionary-astronomers that had arrived
in Siam on 24 September 1685 as part of a
French diplomatic mission. This mission result-
ed from efforts by King Narai and his principal
adviser Constantine Phaulkon (1647–1688;
Sioris, 1988) to build closer diplomatic relations
between Siam and France. This initiative was
seen as a counter to the growing economic pres-
ence of the Dutch in Siam (see Cruysse, 2002;
Hutchinson, 1933), and fortuitously, at the time
Louis XIV (1638–1715) was keen to establish a
major trading facility in Siam (Love, 1994a;
1994b).
Leading the French mission was the diplomat
Alexandre Chevalier de Chaumont (1640–1710;
see Chaumont, 1686), who was accompanied by
the notorious transvestite François-Timoléone
Choisy (1644–1724; see Choisy, 1687), Father
Bénigne Vachet (1641–1720) from la Société
des Missions Étrangères de Paris (who had liv-
ed in Siam since 1671), and the six Jesuits list-
ed in Table 4. These six missionary-astronomers
had been
... sent out by Louis XIV., under a royal patent,
to carry out scientific work in the Indies and in
China, in order, as the patent puts it, ―to
establish Security in Navigation and to improve
Sciences and Arts.‖ (Giblin, 1909: 1).
Leading the missionary-astronomers was Father
Jean de Fontaney, and with the exception of Guy
Tachard,4 they were bound for China but had to
sojourn in Siam until the end of 1687. Conse-
quently, they were able to observe the Decem-
ber 1685 lunar eclipse.
It is significant that before they left France,
Tachard and the other five Jesuit astronomers
were admitted to the Académie Royale des
Sciences [in Paris], and supplied with astro-
nomical instruments on the understanding that
these would be used—among other things—
to determine the latitude and longitude of dif-
ferent geographical features and population
centres … [They also] were supplied with
tables of Jovian satellite phenomena, courtesy
of Paris Observatory, and various reference
books and charts. (Orchiston et al., 2016: 31).
2.3.2 The Location of the Observing Site
The December 1685 lunar eclipse was observed
from Lop Buri, not from Ayutthaya. Although
Ayutthaya was the capital of Siam, King Narai
developed Lop Buri as an attractive alternative
capital (see Thavornthanasan, 1986), and he
preferred to spend up to nine months each year
there. When members of the French delegation
arrived in Lop Buri (or ‗Louvo‘ as it was usually
referred to)5 they were extremely impressed,
finding a ―… town which is, so to speak, in the
Kingdom of Siam what Versailles is in France.‖
(Gervaise, 1689).
Although he had a commodious palace in the
centre of Lop Buri, King Narai also had a
‗country retreat‘ in the form of a ―... very roomy
Palace ... surrounded by brick walls fairly high.‖
(Giblin, 1904: 11), located at the water reservoir
called ‗Tale Chup-sawn‘ about 4 km east of Lop
Buri (Giblin, 1904: 22). This artificial lake was
described by Father Tachard:
There is a large stretch of water which
makes of it a peninsula [where King Narai‘s
‗country retreat‘ was located], and on this water
the King of Siam has built two frigates with six
small pieces of cannon, on which this
Prince takes pleasure in going about. Beyond
this canal [lake] is a forest, 15–20 leagues in
extent and full of Elephants, Rhinoceros,
Tigers, Deer and Gazelles. (Giblin, 1904: 12).
Figure 4 shows the location of the water reser-
voir and the ‗country retreat‘ relative to King
Narai‘s palace in Lop Buri and Wat San Paulo,
the observatory that was later built for the Jesuit
missionary-astronomers.6
King Narai used his ‗country retreat‘ palace
when he went on hunting and
... pleasure trips to the forests abounding with
every variety of trees and to the wild moun-
tain scenery abounding in birds and beasts,
and [he] was enchanted with the romantic
scenery of the region. (Smith, 1880).
There is some confusion in the literature about

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 102
Figure 4: A map of Lop Buri showing the location of King Narai‘s water reservoir and his ‗country retreat‘ in relation to his palace
and Wat San Paulo. The blue dots mark the position of the 12‒13 feet high earth embankment that was erected to stop run-off from
the mountains to the east, thereby forming the water reservoir. During his survey, Mr Irwin noted that terracotta pipes had carried
water from the south-western corner of the water reservoir to King Narai‘s palace (map modifications: Wayne Orchiston).
the location where the French contingent made
their observations (e.g. see Soonthornthum,
2011), but a careful analysis quickly resolves
this issue. When King Narai met the French
astronomers in Lop Buri on 22 November 1985
he invited them to join him and observe the
eclipse from his ‗country retreat‘.
2.3.3 Observations of the Eclipse
In preparing for the eclipse, Phaulkon and the
Jesuit astronomers visited King Narai‘s ‗country
retreat‘ on 9 December and were impressed:
A more convenient spot could not be select-
ed. We saw the Heavens on all sides and
we had all the space necessary for setting up
our instruments. Having settled everything we
returned to Louvo. (Tachard, 1686).7
On 10 December,
… we had cause to be transported to the Tale-
Poussonne our telescopes and a spring clock
very trustworthy and regulated by the Sun …
[so that we could] observe there the Eclipse,
according to the orders of the King. (ibid.).
They set up their telescopes and the clock on a
terrace beside the water reservoir, and after rest-
ing for 3–4 hours they went to their observing
site. They noted that by this time ―It was then
nearly three hours after mid-night.‖ (ibid.).
By good fortune the night was clear, and
We prepared for the King a very long tele-
scope of 5 feet [length] in a window of a
saloon which opened on the corridor [terrace]
in which we were. (ibid.).
It is interesting that although the presents that
King Louis XIV gave King Narai included tele-
scopes, the Jesuit astronomers chose to set up
one of their own telescopes for King Narai to use.
But—as we shall see—they selected the wrong
telescope.
Once the eclipse had begun,
… the King was informed and came at once to

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Figure 5: A drawing showing King Narai and the Jesuit astronomers observing the 11 December 1685 total lunar eclipse from the
King‘s country retreat which was on an island in the water reservoir that was located to the northeast of his palace in Lop Buri
(en.wikipedia.com).
the window. We were seated on Persian mats,
some with telescopes, others with the clock,
others ready to write the time of the obser-
vation. We saluted His Majesty with a pro-
found bow, after which the observations were
begun. (Tachard, 1686).
Subsequently, King Narai
… wished to look through a telescope 12 feet
long, which Father de Fontaney was using,
and we immediately carried it to him. He allow-
ed us to rise and stand up in his presence,
and he was quite willing to look through the
Telescope after we had done so, for it was
necessary to put it in position to show it to him.
Those who know the respectful attitude
which Siamese Kings expect from those who
may be in their presence have spoken to us of
this favour as of something very unique. (ibid.).
Figure 5 is a drawing that was published later,
and purportedly shows the Jesuit astronomers
and King Narai observing the eclipse.8 Else-
where (Orchiston et al., 2016) we have shown
that this drawing contains considerable artistic
licence and should not be regarded as a realistic
representation of the eclipse observations.
Be that as it may, King Narai apparently en-
joyed observing the eclipse, and he
… expressed a special satisfaction seeing all
the spots [craters, etc.] of the Moon in the
Telescope, and in seeing that the plan [map]
which had been drawn of it at the Paris
Observatory agreed with it so well. He put
several questions to us during the Eclipse. For
example: Why the Moon appeared upside
down in the Telescope? Why one could still
see the part of the Moon which was eclipsed?
What time was it at Paris? What could be the
utility of such observations made at the same
time at two places at such a distance apart?
&c. (Tachard, 1686).
The map of the Moon to which Tachard refers
was prepared in 1678 and on 18 February 1679
was presented to the Academy of Sciences in
Paris by Jean Dominique Cassini, the Director of
Paris Observatory (Launay, 2003).
After the eclipse, the French computed the
longitude of Lop Buri as 121° 02′ E of the island
of El Hierro. Meanwhile, the latitude of Lop Buri
later was reported to be 14° 48′ 17″ N (Tachard,
1689). The currently accepted value is 14° 48′
00″ N, while Lop Buri is now known to be 118°
42′ E of the island of El Hierro.

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Table 5: Details of the lunar eclipse of 30 November 1686.
Umbral
Phase
Local
Time
Moon
Altitude Azimuith
Sun
Altitude Azimuth
Start
04h 40m
+24° 288°
‒25° 107°
Middle
06h 00m
+06° 291°
‒07° 111°
End
07h 20m
‒11° 297°
+11° 116°
For further information about the 1685 eclipse
and the dynamic socio-political environment in
which it was observed see Orchiston et al.
(2016), while Gislén et al. (2018) provide a de-
tailed examination of the contact timings for
different lunar craters and other features.
2.4 The Lunar Eclipse of 30 November 1686
In Table 5 we list the start, middle and end times
of the umbral phase of the partial lunar eclipse in
local time, along with the positions of the Moon
and Sun to the nearest degree, as observed from
Lop Buri. As the table illustrates, this eclipse be-
gan in the morning not long before the begin-
ning of astronomical twilight (the Sun was still
25° below the horizon), and the Moon was in the
western sky. By mid-eclipse, when 51% of the
Moon‘s diameter was in the Earth‘s shadow, civil
twilight was about to begin; around this time, the
sky would have been blue all over and normal
daylight activities could have commenced, even
though some of the brightest stars would still have
been visible. As the twilight continued to increase
in brightness, the Moon continued to move even
lower in the western sky, setting at sunrise, which
occurred at 06h 27m local time (before the eclipse
had ended). In the period just before sunrise, the
Moon would have been far less prominent due
to its low altitude and the quite bright twilight.
2.4.1 Observations of the Eclipse
It is interesting that not all of the Jesuit ast-
ronomers mentioned in Table 4 observed this
eclipse, and that they were joined by others.
Furthermore, the observations were carried from
Ayutthaya and Lop Buri. Relevant information
is summarised below in Table 6. Of the original
contingent of six Jesuit missionary-astronomers
only Guy Tachard missed this eclipse, but his
absence is excusable for he was in France at
the time (see Section 2.5.2, below).
According to the information assembled by
Bhumadhon (2000), in Ayutthaya the eclipse was
observed from the terrace and backyard of an
unidentified house (presumably located in the
Portuguese sector of the city), while in Lop Buri,
Fathers Bouvet, de Fontaney and Malbonard as-
sembled at the house of Louis Laneau (1637‒
1696), the Patriarch of Metellopolis and Head of
the French Foreign Missions in Siam, along with
other local priests. Father Malbonard was ident-
ified as the leader of the monks at Ayutthaya
(Bhumadhon, 2000). It is reported that King Narai
planned to join Fathers Bouvet and Fontaney
and observe the eclipse, but at the appointed
time he was too busy to do so (ibid.).
A notable outcome of these eclipse obser-
vations was the discovery that Lop Buri was just
12 km east of Ayutthaya (ibid.).
The foregoing is merely an interim report on
this eclipse. Records of the observations are
housed at Paris Observatory, and have still to
be studied in detail.
2.5 The Lunar Eclipse of 16 April 1688
In Table 7 we list the start, middle and end times
of the umbral phase of the partial lunar eclipse in
local time, along with the positions of the Moon
and Sun to the nearest degree, as observed from
Lop Buri. As the table illustrates, this eclipse was
visible on the evening of 15‒16 April in the few
hours following midnight in a completely dark sky,
ending long before the beginning of astronomi-
cal twilight. The event began with the Moon very
high in the southern sky. By mid-eclipse, when
59% of the Moon‘s diameter was in the Earth‘s
shadow, the Moon was still almost as high but in
the south west, and at the end of the event it
was somewhat farther west, but still almost half
way between the horizon and the zenith.
2.5.1 Observers of the Eclipse
This lunar eclipse was observed by a new con-
tingent of French Jesuit missionary-astronomers,
whose presence in Siam can be traced back to
unbridled success of the total lunar eclipse of
December 1685 and the observations carried out
at King Narai‘s ‗water reservoir‘ palace.
On 15 December 1685, just a few days after
the eclipse, Chevalier de Chaumont set sail for
France, accompanied by Father Tachard and a
Siamese delegation led by Kosa Pan. King Narai
was so impressed by the Jesuit observations of
Table 6: Observers of the total lunar eclipse of 30 November 1686 and their instruments (after Bhumadhon, 2000: 47‒49).
Observing Site
Observers
Instruments
Ayutthaya
Father Jean-François Gerbillon
Mr de Lamar (Royal Engineer of Siam)
Father Louis le Comte
Mr Verét (Director of the French East India Company in Ayutthaya)
Father Claude de Visdelou
Three telescopes with focal length
of 2.5, 6 and 12 feet, respectively.
A small pendulum clock.
Lop Buri
Father Joachim Bouvet
Father Jean de Fontaney
Father John Baptist Malbonard
―Other priests‖
Two telescopes, one with a focal
length of 5 feet.
A small pendulum clock.

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 105
the recent eclipse that he sent King Louis XIV a
letter inviting him to send a second contingent of
Jesuit missionary-astronomers to Siam (see Or-
chiston et al., 2018b).
Father Tachard (1689) explains how this came
about:
... Phaulcon conversed with the King about ob-
taining 12 Jesuit Mathematicians, with the idea of
building an observatory similar to those at Paris
and at Peking. He explained to His Majesty the
glory and utility which would accrue to him
and the advantage which his subjects would
draw from these from which they would learn
the most beautiful Arts and finest Sciences of
Europe. The King consented to this project, and
it was decided that Tachard should return to
France for the Jesuits. (Tachard, 1689).
We can see that in next to no time Father Tach-
ard ―… had become an astronomical advisor to
King Narai and Constantine Phaulkon and a
scientific ambassador for King Narai …‖ (Orch-
iston et al., 2018b; cf. Giblin, 1904), but Smithies
(1994) and Cruysse (1992) both take a rather
jaundiced view of Father Tachard‘s political acu-
men (see Orchiston et al., 2016: 31‒32).
When he sailed for France in December 1685,
Father Tachard carried not only the letter from
King Narai to King Louis XIV but also a letter
from Constantine Phaulkon to Father François
de la Chaise (1624–1709), King Louis‘ personal
confessor in Paris. In part, this letter reveals
King Narai‘s plans to rapidly develop Western
astronomy in Siam:
The King my master having already ordered
the Father Superior to select a site at Louvo [Lop
Buri], and another at Ayutia, to build Churches,
Observatories and Houses, which may seem to
him proper, I undertake at the same time to give
orders that all these will be ready to receive the
Fathers on their arrival. If the six Mathematicians
(the Fathers and my Brothers), have been able to
accomplish so much in two months what will not
fifty or more do in the space of twenty years.
(Tachard, 1689; our italics).
Table 7: Details of the lunar eclipse of 16 April 1688.
Umbral
Phase
Local
Time
Moon
Altitude Azimuth
Sun
Altitude Azimuth
Start
00h 11m
+65° 177°
‒65° 356°
Middle
01h 37m
+58° 220°
‒58° 040°
End
03h 04m
+42° 241°
‒42° 061°
If nothing else, the above letter assumed that
King Louis XIV would accede to King Narai‘s
request for more Jesuit astronomers, and this is
precisely what came to pass. Indeed, King Louis
XIV was pleased with what the six French ast-
ronomers had been able to achieve in the short
time they had been in Siam so he obliged by
sending not twelve, but sixteen, new Jesuit
missionary-astronomers (Tachard, 1689), and
they are listed in Table 8.9 They, Father Tachard
and the new ‗Envoy Extraordinary from Louis
XIV to the King of Siam‘, Simon de la Loubère
(1642–1729) arrived in Siam at the end of Sep-
tember 1687 and went straight to Ayutthaya.
But when the contingent of new missionary-
astronomers visited Lop Buri they were not only
welcomed by the original Jesuit contingent but
also discovered Wat San Paulo,10 one of the
new observatories promised by Phaulkon (and
mentioned in his letter to Father François de la
Chaise). A contemporary drawing of this im-
pressive astronomical facility is reproduced here
in Figure 6.11
The plan that the first contingent of French
Jesuit missionary-astronomers, except Father
Tachard, would go to China eventuated towards
the end of 1687, and Wat San Paulo was left in
the care of Father Tachard and the newly
arrived astronomers. But all this changed in Jan-
uary 1688 when Father Tachard sailed once more
for Europe, destined for Paris and the Vatican as
King Narai‘s personal representative (Smithies
and Bressan, 2001). Father Tachard left Father
le Royer in charge of the Observatory (Smithies,
2003).
Table 8: Jesuit missionary-astronomers who embarked for Siam in 1687 with the second French mission (after Udias, 2003: 54).
Name
Birth/Death Dates
Ultimate Fate
Claude de Bèze
1657–1695
Returned to France
Jean Venant Bouchet
1655–1732
Went to Pondicherry, India, and carried out astronomy
Charles de la Breuille
1653–1693
Remained in Siam with Portuguese Jesuits in Ayutthaya; died in a
shipwreck in 1693
Jean Colusson
????–1722
????
Patrice Comilh
1658–1721
Returned to France
Charles Dolu
1655–1740
Went to Pondicherry, India
Jacques Duchatz
1652–1693
Died in a shipwreck in 1693
Pierre d‘Espagnac
1650–1689
Died en route from Bangkok to India in 1688
Marcel Le Blanc
1653–1693
Died in a shipwreck in 1693
Jean Richaud
1633–1693
Went to Pondicherry, India; carried out astronomy in India; died in a
shipwreck in 1693
Louis Rochette
1646–1687
Died en route from France to Siam in 1687
Abraham le Royer
1646–1715
????
Pierre de Saint-Martin
???? –1689
Died en route from Bangkok to India in 1688
Francois Thionville
1650–1691
????

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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Figure 6: A contemporary painting of Wat San Paulo, with its distinctive 4-storey observatory (Wikimedia Commons).
2.5.2 Observations of the Eclipse
King Narai observed the 16 April 1688 lunar
eclipse from his palace in Lop Buri together with
―… his Brahmin astrologer, and he even sent to
the [Jesuit] Fathers a mandarin to ask them some
questions.‖ (Le Blanc, 1692). Meanwhile, the
Jesuits carried out their observations indepen-
dently from Wat San Paulo (ibid.). As it turned
out, this was destined to be the first and the last
eclipse observed from Wat San Paulo by the
Jesuit missionary-astronomers.
The records of this eclipse are preserved in
Paris, and have yet to be studied in detail.
Figure 7: A map showing the path of totality in blue of the so-
lar eclipse of 30 April 1688 (after Espenak and Meeus, 2006).
2.6 The Partial Solar Eclipse of 30 April 1688
The final seventeenth century eclipse observed
from Siam by the second contingent of French
missionary-astronomers was the 30 April 1688
solar eclipse. This occurred just two weeks after
the 15‒16 April lunar eclipse.
As Figure 7 and Table 9 reveal, this was a
partial solar eclipse as viewed from Siam, with
the Sun in the eastern morning sky. At mid-
eclipse, 73% of the Sun‘s diameter was covered
by the Moon. The eclipse was total along a path
beginning in India, passing to the north of
Thailand, and ending in present-day Canada.
2.6.1 Observations of the Eclipse
King Narai was ill at the time, but in a manu-
script dating to 1688 Major de Beauchamp wrote
that
Mr Constance [Phaulkon] took advantage of this
occasion to speak to him [King Narai] about an
eclipse of the sun which was to occur in a few
days; he asked if his health was strong enough to
allow him to witness it, and [if so] the Jesuit
Fathers would give him this pleasure. He replied
he was, and he should bring them when the
eclipse was to occur. Mr Constance brought the
Jesuit Fathers to the palace; they set up their
telescopes before the king who spent at most
less than half an hour with them because the
weather was not as good as one would have
hoped. (cited by Smithies, 2003:197; our italics).
Figure 8 is a contemporary painting of this event.
This shows the Jesuit astronomers on the roof
of one of the palace buildings, using eyepiece
projection to view an image of the Sun on a piece

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Figure 8: A painting showing the observation of the partial solar eclipse of 30 April 1688 by French Jesuit missionary-astronomers
from King Narai‘s palace in Lop Buri, in the company of the King and his prostrated Court astrologers(en.wikipedia.org).
of paper or card. Prostrated and surrounding
the Jesuit astronomers are King Narai‘s Court
astrologers, while the King is seen at the win-
dow on the right, being briefed, probably, by Fa-
ther le Royer. Constantine Phaulkon is most
likely the seated non-Jesuit, directly behind the
telescope. Note that Figure 8 includes a degree
of artistic licence, for it shows only one astro-
nomical telescope, not the ‗telescopes‘ reported
by Major de Beauchamp.
Further details of the Siamese observations
of this eclipse are presented by Gislén et al.
(2018).
To our knowledge, the solar eclipse April of
1688 was the last astronomical event that King
Narai witnessed. His passion for Western ast-
ronomy, reliance on Constance Phaulkon, tol-
erance of Roman Catholicism and eagerness to
foster closer ties between France and Siam
created increasing disquiet among some mem-
bers of the Royal Family, in the Siamese Court
and amongst Buddhist monks. This culminat-
ed in the staging of a coup d’etat by Phra
Phetracha, King Narai‘s foster brother, and the
King and his supporters were arrested. On 5
June 1688 Phaulkon, King Narai‘s son and other
supporters were executed, and an ailing King
Narai died soon after, on 11 July (Cruysse, 2002;
Smithies, 2002). It has been suggested that it
was poisoning that led to his lingering, and ulti-
mately terminal, illness.
For ‗Western astronomy‘ in Siam the result
was disastrous:
Pra Phetracha then installed himself as the
King of Ayutthaya, and upon reversing King
Narai‘s progressive policies closed Siam‘s bor-
ders to the West and expelled most of the
foreigners living there ... Wat San Paulo was
closed, and all but one of the Jesuit astron-
omers quickly moved to the French fort in
Bangkok before sailing to India … This brought
a sudden and totally unexpected end to an all-
too-short, yet extremely productive, period of
scientific astronomical activity in Siam (Orchis-
ton et al., 2018b).
After this, almost two hundred years would pass
before Western astronomy would return to Siam.
2.7 The Total Solar Eclipse of 18 August 1868
This is a famous eclipse in the annals of astron-
omy, and we would describe it as a ‗watershed
event‘. Astronomical knowledge expanded enor-
Table 9: Details of the 30 April 1688 partial solar eclipse.
Phase
Local
Time
Sun
Altitude Azimuth
Start
06h 40m
+10° 077°
Middle
07h 35m
+23° 080°
End
08h 35m
+37° 082°

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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Figure 9: A map showing the path of totality in blue of the
solar eclipse of 18 August 1868 (after Espenak and Meeus,
2006).
mously during the second half of the nineteenth
century (Clerke, 1903), when photography and
spectroscopy were applied to astronomy (see
Hearnshaw, 2009; Hughes, 2013). The solar
corona finally was accepted as a tenuous outer
atmosphere of the Sun rather than a mysterious
terrestrial or lunar feature, and the basic chemi-
cal composition of the chromosphere, promin-
ences and the corona were firmly established.
In fact it was the spectroscopic observations
during the 18 August 1868 total solar eclipse
that led to major breakthroughs (see Cottam and
Figure 10: A map showing Wah-Koa (the red bull‘s eye) and
the path of totality of the 1868 eclipse across Siam (map
modification: Wayne Orchiston).
Orchiston, 2015; Nath, 2013). The path of total-
ity is shown in Figure 9, and the eclipse was ob-
served from Aden, India (see Launay, 2012;
Nath, 2014; Orchiston et al., 2017), Siam (Orch-
iston and Orchiston, 2017), and the Dutch East
Indies (present-day Indonesia; see Mumpuni et
al., 2017), but
… the most important observations—the ones
that led to the aforementioned ‗major break-
throughs‘—came predominantly from India.
(Kochhar and Orchiston, 2017: 737‒738).
What of the observations made from Siam?
2.7.1 The French Expedition to Siam: Observers
of the Eclipse
The ‗Father of Thai Science‘, King Rama IV (1804
‒1868; Saibejra, 2006) had a keen interest in
astronomy (Aubin, 2010), just like King Narai, and
apart from organising his own observing exped-
ition and attracting local political dignitaries such
as Singapore‘s Sir Harry Ord (see Orchiston and
Orchiston, 2019), he also invited a team of
French professional astronomers to visit Siam
and observe the eclipse from Wah-koa on the
west coast of the Gulf of Thailand (see Figure 10).
Leading the French expedition was the Dir-
ector of Marseilles Observatory Édouard Jean-
Marie Stephan (1837‒1923; Figure 11a; Tobin,
2014), who was assisted by two Paris Observa-
tory astronomers, Georges-Antoine-Pons Rayet
(1839‒1906; Figure 11b; Baum, 2014) and
François-Félix Tisserand (1845 ‒1896; Figure
11c; Débarbat, 2014).
2.7.2 French Observations of the Eclipse
The French set up their observing camp on an-
cient sand dunes adjacent to the beach at Wah-
Koa (Figure 12), their principal instruments be-
ing 40-cm and 20-cm reflectors with silver-on-
glass primary mirrors, a 15-cm refractor, a merid-
ian telescope and an astronomical clock.
When the French expedition reached Wah-
koa, Stephan
… was heartened to find that Mr Hatt [a local
hydrograpic engineer assisting the expedition]
had been far from idle: before leaving Saigon
he had arranged for prefabricated observator-
ies to be built for the meridian telescope and
the Cauche refractor, and these were now on
site. Meanwhile, he also had arranged for the
local people to build a very large bamboo
house parallel to the beach. This was fully
80m in length, and was open towards the sea
and flanked by two long galleries which were
subdivided into numerous compartments.
A flat area to the south-west of the large
bamboo building was reserved for the astro-
nomical instruments, and their installation now
became the main priority of the eclipse party.
Mr Hatt had successfully erected a large
granite column inside the ‗meridian house‘,

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 109
Figure 11a (left): Édouard Stephan (en.wikipedia.org); Figure 11b (centre): Georges Rayet (adapted from Astrophysical Journal,
1907: facing page 53); Figure 11c (right): Felix Tisserand (after Bulletin de la Société Astronomique de France, 1913)
Figure 12: A photograph by Rayet of the French eclipse camp, showing instrument huts and the 40-cm (left) and 20-cm (right)
reflecting telescopes set up outdoors (courtesy: Archives, Observatoire de Marseille, 132 J 84).
and the meridian telescope was attached to
this, and the astronomical clock was installed
on its own column in this same building.
(Orchiston and Orchiston, 2017: 305).
With totality lasting an exceptionally long 6
minutes and 57 seconds,12 this eclipse promised
exciting research opportunities, but the French
team must have been disheartened on the morn-
ing of 18 August when the sky was completely
covered by clouds and it was raining just a few
miles north-east of their observing site. But ten
minutes before totality most of the clouds dis-
appeared, and the astronomers were able to
observe the eclipse.
The French had no photographic equipment
at Wah-koa, so they relied on visual and spectro-
scopic observations, with particular interest in
the form of the corona and the locations and
nature of prominences. Stephan (1869: 25)
concentrated on the prominences (he called them
‗protuberances‘), ―… which appeared to me in
the big telescope in marvellous clarity …‖ Three
of Stephan‘s drawings showing prominences and
the corona are reproduced here in Figure 13.
Meanwhile, Rayet subjected the chromo-
sphere and the most prominent prominence to
spectroscopic scrutiny and recorded a number
of emission lines. He tried to correlate these
with known lines in the solar spectrum, but mis-
took one prominent line for the well-known D line

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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Figure 13: Three drawings of the 18 August 1868 total solar
eclipse by Édouard Stephan (en.wikipedia.org).
Figure 14: A map showing the path of totality of the solar
eclipse of 6 April 1875 (after Espenak and Meeus, 2006).
of sodium. In fact, this marked a new element,
first mentioned by Madras Observatory Director
Norman Robert Pogson (1829‒1891; Snedegar,
2014), which would later be named helium (after
‗helios‘, the Greek God of the Sun). So Rayet
… was not party to the discovery … Without
doubt, this ‗missed opportunity‘ arose from
Rayet‘s familiarity with stellar rather than solar
spectra. Had he made the connection, his
name would now be much better known as the
co-discoverer of helium rather than of Wolf-
Rayet stars. (Orchiston and Orchiston, 2017:
315).
Nonetheless, the French observations of this
eclipse were a success, and
… useful new data on the nature of the
prominences were accumulated, even if the
overall scientific outcomes paled into insignif-
icance when measured against those pub-
lished by Jules Janssen on the basis of his
observations of this same eclipse made from
India. (ibid.).
For further information about the French ex-
pedition to Siam in 1868 and their observations
of the 18 August total solar eclipse see Orchis-
ton and Orchiston (2017).
Meanwhile, observations of the eclipse by
members of King Rama IV‘s expedition and Sir
Harry Ord‘s party made little contribution to
science and so are not discussed here. How-
ever, this eclipse was used very astutely by King
Rama IV as a political weapon against the Brit-
ish and the French, both of whom had colonial
aspirations involving Siam (see Aubin, 2010;
Orchiston and Orchiston, 2019).
2.8 The Total Solar Eclipse of 6 April 1875
As Figure 14 illustrates, the path of totality of the
6 April 1875 total solar eclipse passed through
the Gulf of Thailand (not far north of where the
1868 eclipse was observed from). As well as
offering a chance to build on the spectroscopic
success of the 1868 eclipse and continue to ex-
plore the form of the corona, the 1875 event
also invited astronomers to investigate the myst-
erious green coronal line, K 1471, that American
astronomers had discovered during the 7 Aug-
ust 1869 total solar eclipse and named ‗coron-
ium‘ (see Maunder, 1899).
2.8.1 The British Expedition to Siam: Observers
of the Eclipse
King Rama IV had contracted malaria when he
was at Wah-Koa observing the 1868 solar
eclipse and he died soon afterwards, so in 1875
it was his son, King Rama V (1853‒1910; also
known as Chulalongkorn) who invited foreign
astronomers to Siam to observe the eclipse,
―Inspired by the memory of his father and his
[own] great interest in and knowledge of astrono-

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 111
my …‖ (Hutawarakorn-Kramer and Kramer,
2017: 319; our italics). But on this occasion he
invited the British and the French, and both
accepted. While the famous French astronomer
Pierre Jules César Janssen (1824‒1907; Launay,
2012) accepted King Rama V‘s invitation, it was
the British expedition that would make most
impact (see Lockyer and Schuster, 1878), and is
discussed here.
The Royal Society decided to send an exped-
ition to Siam, and leading it was the youthful Man-
chester University astronomer, Arthur Schuster
(1852‒1934; Figure 15; Knill, 2014) who was
only 23 years of age at the time. As Hutawara-
korn-Kramer and Kramer, 2017: 320) point out,
Schuster ―… considered the task to lead the ex-
pedition a great challenge, the outcome of which
would determine his future career.‖
2.8.2 British Observations of the Eclipse
After a 45-day sea voyage from England, the
British party reached Siam just eight days before
the eclipse occurred. But when they arrived at
their observing camp on sand dunes near the
Chao Lai Peninsula (see Figure 16) they found
that the Siamese had already erected houses
for them (e.g. see Figure 17) and an observatory
building. Each house contained a dining room,
bedrooms, bathroom facilities and storage space
for provisions, while
The observatory consisted of two parts,
separated by about 35 m. The smaller part
was intended for a siderostat to obtain a
spectrum of the prominences and the lower
corona … The larger part of the observatory
was bounded by a dark room on each side,
with preparation of the photographic plates on
one side and development of them on the
other (Lockyer and Schuster 1878). The main
part contained an equatorial telescope with a
prismatic camera which was of shorter focal
length than the camera attached to the sid-
erostat … Another equatorial telescope, which
was lent to the expedition, had a spectro-
scopic camera attached in order to also obtain
spectra of the prominences and the corona. In
addition, a number of small cameras were
available, the pictures from which were to be
supplemented by sketches made during the
eclipse. (Hutawarakorn-Kramer and Kramer,
2017: 321).
As this quotation suggests, the main research
focus of the expedition was to be the chemical
composition of prominences and the corona,
and the aforementioned siderostat is shown in
Figure 18.
Fortunately, clear skies greeted the astrono-
mers on 6 April 1875, and totality commenced at
1130 hrs, but unfortunately,
No useful results were obtained with the
spectroscopic camera mounted on the equa-
torial telescope. Lockyer and Schuster (1878)
Figure 15: Arthur Schuster (en.wikipedia.org).
later attributed this failure to the fact that the
telescope used was not designed for this
purpose. (Hutawarakorn-Kramer and Kramer,
2017: 322).
However, spectroscopic studies made with the
siderostat were a success, and Lockyer and
Schuster (1878) summarized the key results,
which included:
(1) The upper corona was found to emit a ‗hom-
ogeneous‘ photographic spectrum which was
attributed to the ―… hydrogen line near (Fraun-
hofer line) G.‖
Figure 16: A map showing the Chao Lai Peninsula eclipse
site (the red bull‘s eye) and the path of totality of the 1875
eclipse across Siam (map modification: Wayne Orchiston).

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Figure 17: One of the houses erected for the British expedition (courtesy: Royal Astronomical Society).
Figure 18: The siderostat used during the expedition, with its protective cover removed. The associated telescope and
spectroscopic camera were located in the adjacent hut (courtesy: Royal Astronomical Society).

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
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(2) The lower corona was found to emit a strong
continuous spectrum extending into the UV
up to a wavelength of 353 nm (i.e. ―beyond
N‖), reaching to a height of about 3′ from the
Sun.
(3) Photographs showed that the extent of the
corona rapidly increased with increasing ex-
posure time, suggesting that the corona had
no definite outline.
No mention was made of the ‗coronium‘ line.
Much later, Schuster (1932) noted that it was
their observations of the 1875 eclipse that docu-
mented the existence of calcium in prominences
and the chromosphere for the first time.
For further details of the British expedition see
Hutawarakorn-Kramer and Kramer (2017) and
Euarchukiati (2019).
Meanwhile, as with the 1868 eclipse, observa-
tions of the 1875 eclipse by members of the Royal
expedition made no significant contributions to
solar physics, so they are not discussed here.
2.9 The Total Solar Eclipse of 9 May 1929
The path of totality of this eclipse crossed Thai-
land, Malaysia, Indochina, Vietnam and the Philip-
pines (Figure 19), and attracted eclipse parties
from England, France, Germany, Holland, Japan
and the USA (see Table 10). With totality last-
ing about five minutes, this eclipse offered not
only an opportunity to investigate the chemical
composition of the corona but also to again con-
firm Einstein‘s General Theory of Relativity.
In this paper we will discuss only the exped-
itions that went to Siam. There were two—from
Britain and Germany—both there at the invita-
tion of King Rama VII. The King was convinced
that the 1929 eclipse observations would benefit
science and at the same time ―…create good re-
lations between Siam and European countries.‖
(Soonthornthum et al., 2019). So an Eclipse
Committee was formed, and suitable facilities
were prepared for the two eclipse expeditions.
2.9.1 The British Expedition to Siam: Observers
of the Eclipse
Plans for the British expedition were initiated by
the Astronomer Royal, Sir Frank Dyson (1868‒
1939) in 1926, and it was decided that Prof-
essor Frederick John Marrian Stratton (1881‒
1960; Figure 20; Batten, 2014) from Cambridge
University and Philibert Jacques Melotte (1880‒
1961; Teare, 2014) from the Royal Observatory,
Greenwich, would go to Pattani in the very south
of Siam, near the border with Malaya, while John
Jackson from Greenwich and Dr J.A. Carroll
from the Solar Physics Observatory at Cambridge
would proceed to nearby Alor Star in Malaya (see
Figure 21). Dr Thomas Royds (1884‒1955), Di-
rector of the Kodaikanal Observatory in India, also
was invited to joined Stratton‘s party.
Figure 19: A map showing the path of totality of the solar
eclipse of 9 May 1929 (courtesy: Eclipse Predictions by Fred
Espenak, NASA's GSFC http://eclipse.gsfc.nasa.gov/).
Table 10: Overseas expeditions and the 9 May 1929 total
solar eclipse.
2.9.2 British Observations of the Eclipse
The scientific instruments taken to Pattani includ-
ed two spectrographs, a 13-in f/10.4 astrograph,
a coronagraph and a polariscope. The plan was
to use these to explore the nature of the corona
and photograph stars in the vicinity of the eclips-
Figure 20: Professor Stratton in Japan in 1936 (https://
commons.wikimedia.org/wiki/File:F.J.M._Stratton_astrophysi
cist.png).
Country
Expedition
Observing Site
Siam
British
Pattani
German
Pattani
Federated
Malaya
States
American
Alor Star
British
Alor Star
Japanese
Dutch East
Indies
(Sumatra)
Dutch
Idi
German
Takengong
Japanese
Indochina
French
Poulo Condore Island
Philippines
American (4)
German
Cebu Island

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 114
Figure 21: A map showing the British Pattani (red bull‘s eye)
and Alor Star (blue bull‘s eye) eclipse sites and the path of
totality of the 1929 eclipse across Siam and Malaya (map
modification: Wayne Orchiston).
ed Sun (for the ‗Einstein experiment‘). Unfortun-
ately, heavy clouds prevent any observations on
the day of the eclipse—so from a scientific view-
point, all the preparations and expense had been
for naught.
2.9.3 The German Expedition to Siam:
Observers of the Eclipse
Leading the German expedition was Professor
Hans Oswald Rosenberg (1879‒1940; Theis,
2014) from the University of Kiel, assisted by Dr
D. Stobbe and W. Pape. Their observing camp
was at Khok Pho, Pattani district, 34 km south-
west of the British eclipse camp.
2.9.4 German Observations of the Eclipse
Stratton (1928: 200‒201) reports that
The photometry, and spectrophotometry of the
corona and its spectrum will be examined over
Figure 22: The Sun at totality taken with the
astrograph at the German site at Khok Pho
(courtesy: King Prajadhipok Museum).
a wide range of spectrum with the aid of a
spectrograph of high light-gathering power.
Accordingly, the Germans took four spectro-
graphic cameras to Khok Pho, along with an ast-
rograph.
The sky over Pattani was less than encou-
raging on 9 May. However, because the Ger-
man and British observing camps were at dif-
ferent locations, the Germans were able to take
a few photographs during totality, although
these did not provide details of the solar corona
(e.g. see Figure 22).
2.9.5 King Rama VII and the 1929 Eclipse
It could be argued that Kings Rama IV and V
were Siamese ‗Sun Kings‘, in that they both had
a personal interest in astronomy, organised their
own eclipse expeditions, and observed both
eclipses. However, King Rama VII‘s interest in
eclipses was more political than scientific, so
even had the skies been co-operative on 9 May
1929 he had no plan to carry out the same range
of observations as his illustrious astronomical
predecessors. Certainly he hoped to view the
eclipse, but instead all he could do was visit
the British and German astronomers on the day
before the eclipse (e.g. see Figure 23), and later
commiserate with them.
3 THE EMERGENCE OF ASTRONOMY AT
CHULALONGKORN UNIVERSITY
The 1929 eclipse was the catalyst that led to the
emergence academic astronomy in Siam, and
… in 1930 astronomical research was est-
ablished at Chulalongkorn University in Bang-
kok, the first university in Thailand (and named
after King Rama V). (Soonthornthum, 2017:
280‒281).
Soonthornthum et al. (2019) also report that Col-
onel Phra Salvidhan Nides (Figure 24), a prom-
inent member of the Siamese committee that
organised the construction of the British and
German eclipse camps in 1929 and welcomed
the European astronomers, taught astronomy
courses at Chulalongkorn University for science
and engineering students.
The University‘s interest in solar astronomy
continued when Rawi Bhavilai (1925‒2017; Fig-
ure 25) joined the Physics Department in 1944.
Bhavilai13 would remain at Chulalongkorn Univer-
sity until his retirement in 1986, by which time he
was a full Professor (Prominent astronomer …,
2017). During his tenure he secured a Colombo
Plan Scholarship and studied for an M.Sc.
degree at the University of Adelaide (Knowledge
without bounds, 2008), graduating in 1952. Sub-
sequently, he continued this love affair with
Australian academia by studying for a Ph.D. in
astronomy at the Australian National University
in Canberra, while based at nearby Mount Strom-

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 115
Figure 23: King Rama VII and the Queen visiting the German eclipse camp on 8 May 1929 and inspecting the astrograph (courtesy:
King Prajadhipok Museum).
lo Observatory. In 1965 he was awarded the
doctorate for a thesis titled ―The Structure and
Dynamics of the Solar Chromosphere‖ (Rawi
Bhavilai, 2017).
Professor Bhavilai established a solar re-
search group at Chulalongkorn University and
not long before the publication of his book The
Fine Structure of the Solar Corona (Bhavilai,
1971) a 15-cm f/10 Zeiss solar chromospheric
telescope was installed at the University. This
instrument is described in the book.
This book was one of twenty-one books that
Professor Bhavilai wrote or edited, but most
were in the fields of literature and Buddhism. So
although he is well known as an astronomer,
His life‘s work … has seen him explore areas
as diverse as philosophy, physics, Buddhism
and poetry. (Knowledge without bounds,
2008).
Professor Rawi Bhavilai was Thailand‘s first
solar physicist, but by 1989 the Physics Depart-
ment had expanded into astrophysics, and
In October 1989 a 0.45-m reflecting telescope
was donated to Chulalongkorn University by
the Government of Japan under a cultural
grant aid program for the promotion of astro-
nomical education and research in Thailand.
Soonthornthum, 2017: 281).
But Chulalongkorn University was not the
first Thai university to embrace astrophysics, for
this was pioneered in 1977 at Chiang Mai Univer-
sity in northern Thailand, when astronomy be-
came part of the Faculty of Science curriculum
(Soonthornthum, 2017). Initially, research pro-
jects concentrated on stellar astronomy, and
particularly photoelectric photometry. This led,
Figure 24 (left): Colonel Phra Salvidhan Nides, Siam‘s first
university lecturer in astronomy (courtesy: Office of the
National Research Council of Thailand).
Figure 25 (right): Professor Rawi Bhavilai, Siam‘s first solar
physicist (after Knowledge without bounds, 2008).

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 116
ultimately, to the final phase in the development
of professional astronomy and emergence of
astrophysics in Thailand, with the establishment
in 2009 of the National Astronomical Research
Institute of Thailand (NARIT) in Chiang Mai; the
founding Director, Boonrucksar Soonthornthum,
had been an Associate Professor of Astronomy
at the University.
4 THE FOUNDING AND DEVELOPMENT OF
NARIT
As Soonthornthum (2017: 284) has pointed out,
The development of astronomical research in
Thailand took a crucial leap forward when on
20 July 2004 the Government approved the
―Establishment of the National Astronomical
Research Institute of Thailand (NARIT)‖ under
the Ministry of Science and Technology. On 1
January 2009 NARIT was approved by the
Government and officially established with the
status of a public organization responsible for
policy-making and strategic planning in the de-
velopment of astronomy in Thailand.
The growth of NARIT since 2009 has been phen-
omenal, with vibrant schools and public outreach
programs,14 and a Research and Development
Division that carries out wide-ranging astrophys-
ical research.
Some of the observations conducted in the
course of this research have been made with the
Thai National Telescope (TNT), a new 2.4-m
Ritchey-Chrétien telescope (Figure 26) that is lo-
cated near the summit of Doi Inthanon, Thai-
land‘s highest mountain, not far from Chiang Mai
(Figure 27). Her Royal Highness Princess Maha
Chakri Sirindhorn officially opened the TNT in
January 2013 (just four years after NARIT was
founded).
In order to conduct research collaborations
and 24-hour monitoring of target stars, NARIT has
also established an international network of
60-cm to 1-m telescopes sited in Australia, Chile,
China and the USA (see Figure 28).
The latest (and current) phase in the devel-
opment of NARIT‘s astrophysical instrumentation
involves radio astronomy. At the time of writing
this paper (2018) a stand-alone 40-m diame-
ter radio telescope is under construction near
Chiang Mai (see Figure 29). The plan is
… that eventually there will be three identical
dishes in Thailand, in the north, east and
south (to maximize base-lines), and that
these will form a Thai VLBI Network, but
also work closely with the existing VLBI
networks in East Asia (China, Taiwan, South
Korea and Japan) and in Australia-New
Zealand. (Orchiston and Swarup, 2018),
Figure 26: Two views of the automated 2.4-m Ritchey-Chrétien Thai National Telescope. Left: undergoing testing prior to its
installation at the TNO; right: installed and operational at the TNO (courtesy: NARIT).

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 117
NARIT‘s astrophysical research is now con-
ducted by a growing pool of tenured astrono-
mers, post-doctoral fellows, research assistants
and graduate students. Meanwhile, the Thai
Government is promoting this strategy by provid-
ing funding so that students can study overseas
and obtain Ph.D.s in astronomy. Most of these
graduates return to Thailand and to posts at
NARIT or at one of the many universities that now
teach astronomy.
In order to promote astrophysical research
and research collaborations at these universities,
in July 2007 NARIT signed memorandums of un-
Figure 27: The Thai National Observatory (TNO) is located
near the summit of Doi Inthanon, a 2-hour drive west-
southwest of Chiang Mai (travel.mthai.com)
Figure 28: The 0.7-m PlaneWave LDK700 reflector being
installed at the Sierra Remote Observatories, USA, in
December 2015. Third from the left is Dr Saran Pochya-
chinda, the current Director of NARIT (courtesy: NARIT).
derstanding with 24 different universities in Thai-
land, while at an international level NARIT has
similar arrangements with various universities,
observatories and research institutes in more
than 15 countries (Soonthornthum, 2017).
Meanwhile, NARIT has been very active pro-
moting research among Southeast Asian nations,
and following a meeting in 2007 formed SEAAN,
the South East Asian Astronomical Network.
The goals of this network are
Figure 29: NARIT‘s new 40-m radio telescope will be
modeled on this dish at Yebes in Spain (courtesy: NARIT).
… to establish strong research collaborations,
identify key science appropriate to the region,
share instruments and develop and utilize
human resources among South-East Asian
countries. The network now has annual
meetings in different cities throughout the
region, and acts as a regional platform to bring
the advancement in astronomy to each mem-
ber country. Research collaborations have
been organized or are planned in optical and
radio astronomy, in the development of instru-
mentation, and in history of astronomy, not
just within the SEAAN region, but also with
institutes in Australia, China, India, Japan,
Korea and Taiwan. (Soonthornthum, 2017:
289).
One of the primary reasons for the amazing
developments that have occurred lately in Thai
astronomy is the strong support of King Bhumi-
pol Adulyadej (Rama IX; 1927‒2016; Figure 30)
Figure 30: King Bhumipol Adulyadej (Rama
IX) as a young man (Wikimedia.commons).

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 118
Figure 31: Princess Maha Chakri Sirindhorn (right) examines a scale model of the new NARIT headquarters, now known as the
Princess Sirindhorn AstroPark, part of which is still under construction in an outer north-eastern suburb of Chiang Mai. Third from
the right is Professor Boonrucksar Soonthornthum who at the time was the Director of NARIT. The current Director, Dr Saran
Pochyachinda, is second from the right (courtesy: NARIT).
and his second daughter, Princess Maha Chakri
Sirindhorn (Figure 31), both of whom have been
passionate about astronomy. This follows a long-
standing Royal tradition that began with King
Narai, and had circumstances been different it is
possible that the late King would have become a
professional astronomer. Meanwhile Princess
Sirindhorn is an avid ‗eclipse-chaser‘, and also
makes observations and carries out astrophoto-
graphy with various NARIT telescopes (including
the 2.4-m Thai National Telescope).
5 CONCLUDING REMARKS
It is well known that throughout history eclipses
have filled mankind with dread or wonder. But
they have also been party to the development of
‗modern astronomy‘ in many nations and the
foundations upon which astrophysics was built.
This was no more so than in Siam, where over a
period of almost two and a half centuries solar
and lunar eclipses were seminal in the emerg-
ence of ‗modern astronomy‘ and ultimately in the
birth of solar physics and astrophysics.
Moreover, the second half of the nineteenth
century was a critical time in the history of astron-
omy, when spectroscopic, photographic and pol-
ariscopic observations of a succession of total
solar eclipses led to major breakthroughs in so-
lar physics (Clerke, 1893). Siam was able to make
an important contribution in this regard, thanks
to British and French observations of the 1868
and 1875 eclipses.
An underlying theme throughout this paper
has been the significance of royal patronage in
fostering European observations of eclipses,
and especially total solar eclipses, made from
Siam. This patronage was pivotal to the birth of
‗modern astronomy‘ in Siam in the seventeenth
century, and continued during the nineteenth and
twentieth centuries, finally culminating in the
formation of NARIT. France‘s ‗Sun King‘ aside
(see Débarbat, 2015), it could be argued that
there are few other countries in the world where
royal patronage has played so key a role in the
long-term development of astronomy, and espec-
ially in the emergence of astrophysics.
King Rama IV and King Rama V also used
the 1868 and 1875 eclipses as educational ve-
hicles to demonstrate the differences that exist-
ed between Western ‗scientific astronomy‘ and
Siamese ‗traditional astrology‘, and it is notable
that the Thai Royal Family continued this tradi-
tion during the twentieth century. Thus, King
Bhumipol Adulyadej observed the total solar
eclipse of 20 June 1955 and he and Princess
Sirindhorn watched the 24 October 1995 eclipse.

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 119
Both were visible from Thailand, and in 1955
―Radio Thailand station broadcasted a program
about the solar eclipse nationwide for the first
time in Thai history.‖ (Nitiyanant, 2015). By 1995,
Many Thai people were interested [in astron-
omy and the eclipse and they] … travelled to
provinces that the eclipse path passed through
and many Thai television channels broadcast
live views of the eclipse nationwide ... (ibid.).
Finally, in this paper we have seen how
eclipses, and particularly total solar eclipses, can
have important political ramifications. Thus, some
of Siam‘s kings used eclipses, in league with for-
eign policy, to not only foster international rela-
tions but also reinforce Siam‘s independence, as
discussed, for example, by Aubin (2010) and
Orchiston and Orchiston (2019) in the case of
the 1868 eclipse.
6 NOTES
1. Siam officially changed its name to Thailand
in 1939.
2. All of the times listed in Tables 2, 3, 5, 7 and
9 were calculated using Herald‘s OCCULT
v3.6 and the NASA Catalog, which agreed to
within one minute in all instances. ‗Local
Time‘ was defined as UT + 7 hours. The Jes-
uits in Siam in the seventeenth century used
local apparent solar time for their eclipse tim-
ings. This means that for instance the times
given in the table for the 1685 lunar eclipse,
for comparison with the timings of the Jesuits
should be corrected by ‒18 minutes to account
for the time difference between the 7 hour
meridian (105° E) and the meridian of Lop
Buri (100.65° E). Additionally, they should be
corrected by +6 minutes by the equation of
time to get apparent solar time. The start of
the totality, 4:37, will then be corrected to
4:25 local apparent solar time and the time of
the end of the totality, 6:21, will be corrected
to 6:09, both of which are very close to the
times actually reported by the Jesuits.
3. Professor Michael Smithies (2003: 189), argu-
ably the world‘s foremost authority on Siam
of the 1680s, refers to these Jesuits as ―…
mathematicians [and] … astrologers …‖ Today
there is a clear distinction between astrolo-
gers and astronomers, and we believe that
Smithies was misled by the English trans-
lation of Tachard‘s tome, which reads: Rela-
tion of the Voyage to Siam Performed by Six
Jesuits sent by the French King, to the Indies
and China, in the Year 1685, with their
Astrological Observations, and their Remarks
on Natural Philosophy, Geography, Hydro-
graphy, and History (Tachard, 1688). How-
ever, this is a serious mistranslation, because
the original French volume refers specific-
ally to ‗Astronomical Observations‘ and never
mentions astrology.
4. Guy Tachard (1651–1712) would stay behind
and play a key political role in the devel-
opment of scientific astronomy in Siam (see
Orchiston et al., 2016; 2018b).
5. In the 1680s Lop Buri was variously referred
to as Louvo (Tachard, 1686), Louveau (Ger-
vaise, 1689), Luvo (see Giblin, 1904) and La-
wo (ibid.) by the French.
6. Note that Figure 4 is an updated version of
Figure 14 that was published in Orchiston et
al., 2016: 39. In Figure 4 the revised bound-
ary of the water reservoir is now based on
the cadastral map that was prepared by A.J.
Irwin in the 1890s, but was unavailable when
the 2016 paper was researched and written.
7. This quotation and subsequent ones listed as
‗Tachard (1686)‘ are actually taken directly
from Giblin (1909) and are Giblin‘s English
translations of the astronomical excerpts con-
tained in Tachard‘s two-volume work Voyage
de Siam des Pères Jésuites Envoyés par le
Roi aux Indes & à la Chine (1686).
8. The prostrated individuals in this drawing are
King Narai‘s court astrologers.
9. Although Tachard (1689) states that sixteen
Jesuit astronomers went to Siam in 1687,
Udias (2003) could track down only fourteen
when he researched this topic, and these are
individuals listed in Table 6. Smithies (2003:
192) also refers to these astronomers as
‗astrologers‘.
10. There is confusion over the correct spelling
of Wat San Paulo, with both this (correct)
version and ‗Wat San Paolo‘ featuring at
different times on different interpretive panels
at the site itself! Even Soonthornthum (2011:
181) mistakenly uses Wat San Paolo.
11. In fact, by this time only one observatory had
been built (cf. Hodges, 1999). Moreover,
part of the massive building shown in Figure
6 was still under construction when Constan-
tine Phaulkon and King Narai died in June
and July 1688 respectively (Smithies, 2003).
Because of their passing, the planned Ayutt-
haya observatory was never built.
12. This was only 35 seconds shorter than the
longest possible duration of totality of a total
solar eclipse, which is 7 minutes 32 seconds.
13. Other spellings of his name are Rawee Bha-
vilai and Rawī Phāwilai.
14. For details of NARIT‘s education and out-
reach accomplishments see Soonthornthum
(2017).
7 ACKNOWLEDGEMENTS
We wish to thank Visanu Euarchukiati (Bangkok,
Thailand) for locating a copy of A.J. Irwin‘s cad-
astral map of Lop Buri and making this available
to us (so that we could prepare Figure 4). Apart
from the calculations for Tables 2, 3, 5, 7 and 9,
which were performed by the third author of this

W. Orchiston, D.L. Orchiston, M. George et al. Eclipses and Modern Astronomy in Thailand
Page 120
paper, research on the seventeenth century
eclipses was largely based on data gathered by
the first two authors during a detailed literature
survey and on three visits to Lop Buri and
Ayutthaya in 2014 and 2015. We are grateful to
staff from the Lop Buri City Hall, and the
Department of Fine Arts at Kraisorm Siharat
Pavilion (the ‗Water Reservoir Palace‘ in Lop
Buri) for their assistance. Finally, we wish to
thank the King Prajadhipok Museum, Office of
the National Research Council of Thailand, Ob-
servatoire de Marseille and the Royal Astronom-
ical Society for kindly supplying Figures 12, 17,
18, 22, 23 and 24.
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