ANNUAL REPORT FOR 1874. 61 



them under appropriate names. Efforts have been made to overcome 

 this difficulty by chemical analysis, and also by microscopic examina- 

 tion of very thin sections, prepared with great care and skill. In this 

 way it is sometimes found that rocks, having the same general ap- 

 pearance to the eye, are made up by the aggregation of very different 

 minerals. The specimens of rocks and minerals sent in were col- 

 lected and transported with very considerable labor. They are all 

 numbered, and the exact locality from which they were obtained prop- 

 erly designated. They will be of much use in the further prosecu- 

 tion of the survey, and will, at its close, be distributed to the institu- 

 tions entitled to receive them in^ accordance with the law. 



One of the most serious difficulties met with by Maj. Brooks and 

 his party, and which materially retarded the progress of his work, 

 arose from the gross inaccuracies of the government surveys in that 

 part of the state, and the careless and insufficient manner in which 

 the lines and corners were established. Lakes were found having but 

 little resemblance to their representation upon the plats ; streams are 

 made to run where none exist; swamps are laid down where excellent 

 pine-lands yield an abundance of lumber; when a tract of land is 

 " entered," the purchaser may find his quantity or number of acres 

 deficient, or largely in excess. It is matter of common remark 

 among woodsmen in this region, that the Wisconsin surveys are 

 much less reliable than those of Michigan on the opposite side of the 

 river. Under these circumstances, it may be a question whether it is 

 not the duty of the government to resurvey in a more thorough and 

 accurate manner, the public lands in this region of the country before 

 they become of so much value as to lead to endless trouble in attempt- 

 ing to retrace the section lines. 



It is much to be regretted that the several stations of the United 

 States lake survey were not connected with the lines of the public 

 land survey. This would have afforded many points for correcting the 

 maps projected from the land surveys alone. 



At the suggestion of the geological survey, Gen. A. A. Humph- 

 rys, Chief of Engineers, directed that the latitude and longitude of 

 certain points upon the fourth principal meridian, the base, and the 

 correction lines, be ascertained with the utmost exactness. These, 

 being the governing lines of the land surveys, are most important; 

 and it is, therefore, extremely desirable that their exact position 

 should be ascertained. 



As the first fruit of this application, the following determinations 

 were furnished to the survey by Gen. C. B. Comstock, on the 17th 

 of July, 187-i: 



