Army post of Brenham Map No. 7 depicting the location of historic “Camptown” and general location of the distillery from Brass (2011).
Context in source publication
... army post of Brenham Map No. 7 from 1868 represents one of the defining moments in Brenham’s past ( Figure 1). During the Reconstruction period following the Civil War, Company E of the Seventeenth Infantry’s Third Battalion was sent to Brenham in 1865 led by Brevet Major George W. Smith. The camp was constructed east of downtown and quickly came to be called “Camptown” which has previously been geophysicaly examined (Meehan et al. 2015, this issue). The Soldiers presence caused many problems, eventually resulting in a large fire started by the soldiers that engulfed most of the town (Brass, 2011). The map is one of the only references to the location of the distillery. While the general location of the distillery can be determined, the map has several scale issues commonly seen in historic maps. The geophysical study focused on the property located at 507 South Chappell Hill St., Brenham, TX 77833. The Washington County Appraisal District identification number is R42537 and is owned by Blue Bell Creameries, LP (W.C.A.D., 2014). The site has been utilized for several uses in the past decade, including a recreational baseball field in the northern portion of the property. The property also has several small municipal water buildings. The main geophysical interest in the property is in the southern portion near a creek which acts as one of the properties borders. In this area is believed to be the location of one of the first distilleries in Texas. An aerial of the site is shown with the location of the survey area in red (Figure 2). A portion of the army post map has been georectified onto the aerial map to show the putative location of the distillery (Figure 3). Because the army post map suffers from spatial inaccuracy like many historic maps, the location of the buildings should be considered as a hypothesis to test with geophysical techniques. The ultimate objective of the project was to map the location of the unknown structure of the distillery. In order to accomplish this, multiple geophysical techniques were used. The magnetometer allowed the detection of magnetic objects in the sub-surface. Electromagnetic induction measured any relative apparent elctrical conductivity changes in the soil commonly associated with metallic or non-conductive objects such as building foundations. Ground- penetrating radar recorded any relative dielectric permeability contrasts in the subsurface detecting a wide array of sub-surface objects. Each of these techniques has drawbacks when used separately (Clay, 2001), but when combined and correlated, these three measurements provided a more complete picture of any objects present in the sub-surface. Both qualitative and quantitative methods were examined to effectively combine the results of multiple geophysical sensors. The majority of the results presented were completed for an undergraduate thesis by Charles Stanford (Stanford, 2015). The sub-surface mapping of the project location was completed using three geophysical techniques: magnetrometry (MAG), electromagnetic induction (EMI), and ground-penetrating radar (GPR). To tie all three geophysical techniques together, a common site grid was established in the southern area of the property. Care was taken to keep the grid as far away as possible from the municipal water buildings located near Chappell Hill St. Care was taken to minimize the effect of magnetic and electromagnetic properties of the buildings during data acquisition. Other restrictions on the survey area were a sharply dipping creek bank on the southern border of the property, and a chain link fence on the eastern edge of the property. A 40 x 40 meter Cartesian coordinate system grid was constructed. The origin point (0,0) of the grid was placed in the south-east corner. Blaze orange non-magnetic surveyor spikes were used to permanently mark the corners of the grid so that in the future, geophysical surveys could be repeated in the same location The primary purpose of conducting a magnetometer survey was to detect any iron bearing artifacts associated with building structures (Everett 2013). The G-858 Cesium Vapor Magnetometer was used in vertical gradiometer mode. A specialized magnetometer cart was constructed in order to keep the sensor heights constant at 0.4 and 0.9 meters during the survey (Figure 4). Data was collected continuously at 0.5 meter line spacing with 5 meter fiducial lines, with a sampling rate of 0.1 seconds or ...