The Laws Observatory. 491 
Survey which had been loaned in June, 1882, to the University 
of Missouri by J. E. Hilgard, then Superintendent of the 
Coast Survey. 
Description of the Instrument — 
For the following facts concerning Zenith Telescope No. 
3, [ am chiefly indebted to Dr. T. C. Mendenhall, Supt. U. 
S. C. & G. Survey, writing under date of July 13th, 1892. 
‘*Zenith Telescope No. 3 was made by Troughton and 
Simms. Its aperture was 3 inches, focal length 46 inches, 
power of diagonal eyepiece 61 diameters. The angular value 
of one turn of the micrometer screw adopted from 1850 to 
1854 was 46”.63. For the same period one Div. of Level 
A = 1”.099, and one Div. of Level B = 1”.04. 
** In 1874 a Coast Survey observer used the instrument and 
gave as follows: one turn of the micrometer screw = 46”.60 
and one division of Level A = 1”.20. 
‘* The instrument was sent to Prof. Joseph Ficklin of the 
University of Missouri on June 27th, 1882, by Prof. D. P. 
Todd of Amherst College, Massachusetts, and was returned 
to the Coast Survey Office in Washington by Prof. Ficklin 
in August, 1885. 
** It was entirely reconstructed in 1891.’’ 
From the correspondence it appears that Prof. Todd 
determined the constants of the instrument, and found them 
not much different from the values of the level division and 
micrometer revolution determined by the Coast Survey in 
1874, Unfortunately, these results.were destroyed by fire in 
March, 1882, Prof. Todd reports that the instrument was in 
good condition when sent by him to Prof. Ficklin. 
As determined by Professor Ficklin the angular value of 
One level division in terms of revolutions of the micrometer 
Screw is 
0.0269 = 1”.25. 
The individual results for level division are not given. 
