REPORTS OF GEOLOGISTS. lxxxix 



at that date we had ascertained that a large outside area of what had previ- 

 ously been regarded as Carboniferous territory is really of earlier age. Ar- 

 rangements were therefore made by which I became permanently attached to 

 the Survey as the Geologist for Central Texas, and the accompanying report 

 is transmitted as a preliminary statement of the work performed up to the 

 date of going to press with your Annual Report for 1889. 



From June 23, 1889, until September 15, 1889, the personnel of this divis- 

 ion of the Survey was as below: 



Theo. B. Comstock, geologist in charge. 



James C. Nagle, topographer. 



Charles Huppertz, geological aid. 



David W. Spence, aid. 



Oran G-. Bunsen, rodman. 



Harry Spence, rodman (July 25 to September 25, 1889). 



R. V. Sanders, cook. 



Richard Maxwell, hostler. 



No important changes were made after the renewal of work in September, 

 except that Mr. David Spence left at that time, and the funds were insuffi- 

 cient to enable me to supply his place. Mr. Bunsen, however, was partly 

 employed as general aid, in addition to his duties as rodman. Mr. 0. 

 W. Wilcox replaced Harry Spence as rodman late in September, and J. L. 

 Nichols was engaged from late in October until December 5 as cook, in place 

 of R. V. Sanders. Mr. Nagle assumed temporary charge of the field party 

 during my absence in September, so that there was practically no cessation 

 of the work from June to December. 



Upon the return from the field, December 6, the field party was disbanded. 

 Mr. Nagle was retained to work up the topographical notes and sketches, and 

 he has prepared maps with fifty feet contour intervals, upon a scale of 1040 

 feet to one inch, which he has reduced upon one sheet to the scale of 1 2 g 1 

 (about two miles to the inch). This is not yet ready for publication, owing 

 to gaps which remain to be filled. The data for its construction were ob- 

 tained by transit and stadia work with the solar compass, along lines daily- 

 selected by myself with reference to both geologic and topographic needs of 

 our Survey. These lines comprise about 500 miles of geologic sections, the 

 adjacent topography being accurately taken, and the intervening areas being 

 omitted, except where some check could be made upon the work. The tri- 

 angulation of the United States Geological Survey, under Major Powell, 

 affords us a very satisfactory basis, but the sketched topography in the pub- 

 lished maps has been found unreliable, in large measure, owing, it would 

 seem, to rapid work, and to undue dependence upon odometer and aneroid 

 measurements. Some very convincing tests, made by us last season, have 



