Observations on Surveying Instruments. 260 



convinced. For although the latter generally show a high 

 finish, and nice graduations ; I have never seen one that had 

 a convenient disposition of its parts. And they often pre- 

 sent the inconsistency, of a nonius, by which the divisions 

 may be read oft' to every minute, while the needle is so clum- 

 sy that the course cannot be determined, nearer than to half 

 a degree. 



The inaccuracy of surveys has, (as Mr. Gummere very 

 justly observes,) been a more fruitful source of litigation in 

 the United States, than all other causes put together. Hence 

 arises the necessity that every person who practices survey- 

 ing should be provided with good instruments, that error may 

 be avoided as much as possible, and without such instru- 

 ments it is in vain to expect any tolerable degree of accura- 

 cy. Hence also, our government, which has already survey- 

 ed about one hundred and forty millions of acres, and has 

 more than one hundred and thirty millions yet to survey, with 

 a view of the importance of the subject, and with a design to 

 promote accuracy, directs, that no compasses be used in its 

 surveys, but such as have Rittenhouse's improvements. 



In the course of surveying more than three thousand miles, 

 for the United States, and in using compasses manufactured 

 by several of our best artists, although excellent of their kind, 

 I have frequently experienced considerable inconvenience in 

 passing over hilly ground, from not being able to elevate or 

 depress, as the case might require, the forward end of the in- 

 strument. The theodolite is represented by writers on the 

 subject, to be the perfection of instruments for this kind of 

 business, but however well it may be adapted to surveying 

 in an open country ; it is altogether too unwieldy for use in 

 the woods. Considering that an instrument combining the 

 advantages of the theodolite in a portable form, would be a 

 desideratum, I had what I conceived to be such a one made, 

 to order, by Mr. Benj. Piatt, a very ingenious artist of Colum- 

 bus, Ohio — far a representation of which, see Fig. 1.* 



Explanation of the Figure, and description of the instru- 

 ment. 



Fig. 1 represents a view of the " improved elevating com- 

 pass," from a point somewhat lower than the compass box, 



* Mr. Piatt has for some time made compasses on a similar construction, and 

 their superiority is bringing them into general use in the western country. He 

 calls it the patent elevating compass. 



