BAROMETER, ETC. AT THE KEVE OBSERVATORY. 
513 
the latter position, in measuring- by the Cathetometer the divisions of the Standard 
Scale placed vertically at a distance of five feet. In the horizontal position there 
appeared to be no appreciable error in the graduation of the Cathetometer, but 
when vertical its scale was found to be somewhat too long, the measurement of a 
length of 30 inches requiring a correction of -|-0’003 inch. Besides this discrepancy, 
which is probably due to irregular flexure of the bar and to imperfect fitting of the 
sliding frame which carries the telescope and level, the manipulation of the instru- 
ment is exceedingly inconvenient and troublesome, and requires much care and 
patience. It is believed, however, that, when the requisite care and time are be- 
stowed, the measurements, after allowing for the correction mentioned, are accurate. 
A new Cathetometer is at present being construeted by Mr. Beckley at the Obser- 
vatory, which promises greater accuracy and convenience. This instrument is very 
nearly completed, and will be described in a subsequent communication. 
