Use of the Zenith Telescope in Determining Latitudes: 191 
Arr. XXII.—Notes on the Use of the Zenith. Telescope in De- 
termining Latitudes in the Coast Survey, by Talcott’s Method, 
and on the Reduction of the Observations ; by A. D. Bacus, 
Superintendent U. S. Coast Survey.* 
_ Tue method of determining latitudes, by measuring differences 
of meridian zenith distance of two stars, of nearly the same dis- 
tance from, and on opposite sides of, the zenith, employed by 
Capt. Andrew Talcott, late of the U. S. Corps of Engineers, ap- 
ment for each pair of stars, and when the star should enter the 
field ; thenceforward calls each ten seconds, the observer follow- 
* From the Proceedings of the American Association for the Advancement of 
Science, vol. y, (Sth j ineinnati,) p. 151. ; 
. + In this pe ee ane. et os or nat) Bie clamp has been applied for keep- 
t in position, and with great advantage. 
