Proceedings of the Polytecexic Associatiox. 1035 



nected with the base of the scale, and giving the two ten-thou- 

 sandths of a millimeter, legible on the graduated scale beneath ; and 

 1. Of an extremely sensitive level capable of being applied to the 

 telescope, and of determining, when required, its horizontal adjust- 

 ment. The leveling staff used with the omnimeter is not divided, 

 but is of an invariable length, which is defined by two white lines 

 on a black ground, one at the upper end and the other at the lower 

 extremity. The omnimeter is found especially useful in difiicult and 

 hilly ground where leveling in the ordinary way becomes a tedious 

 operation, because the sights are short and are multipled in propor- 

 tion to the rapidity of the incline. AYith the new instnmient the 

 levels may be taken at much greater distances apart, even where 

 considerable angles are made with the horizon. The omnimeter 

 embraces all the advantages of the theodolite and level, and does 

 away with the tedious chain measurements ; furthermore, its opera- 

 tion requires no complicated calculations. 



Mr. T. D. Stetson. — A cheap and simple instrument for measuring 

 distances is a want that is widely felt. Some years ago a Mr. Cran- 

 dall, of western ]^ew York, invented an instrument for measuring 

 distances, which did the work very well. The principle consisted in 

 taking a fixed base, very short, say one foot, and attaching to each 

 end a telescope, which turned on a pivot, and carried an index mov- 

 ing near a graduated arc. By fixing the instrument, and then direct- 

 ing the telescope to the object, the angles at the base of the triangle 

 thus formed are measured, and the distance easily calculated. But in 

 this case it was not necessary to calculate the distance, for instead of 

 having angles marked on the scale the distances themselves were 

 marked off so as to be easily read. This instrument was tried and 

 found to work well for all moderate distances. It was even tried at 

 distances of fifteen miles, and found to give tolerably accurate results. 

 But it fell out of use, and I have not seen one in a long time. 



The chairman made a diagram on the board, and explained the 

 principle upon which the instrument described by Mr. Stetson must 

 have worked. 



A gentleman present remarked that lie had no faith in such instru- 

 ments applied to the measurement of such great distances. The base 

 is so short that the slightest change produced by heat or moisture 

 will vitiate the result to such an extent as to render them worthless. 



Mr. T. D. Stetson. — That brings to my mind the fact that there is 

 a great want in' this direction. Xow, it has been said that in this 



