astronomical observatoeies. 373 



Cambridge, Massachusetts. 



I. Private Ohscrvaiory. 



Loiigitudc from Wasliin.e;ton, 23'" 4l.2G« E. 

 Latitude, 42^ 22' 58.8" N. 

 Director : E. L. Trouvelot. 



II. The Astronomical Observatory of Harvard College. 



J.ou<;\tm\e from Wasbingtoii, 23'" 41.11" E. 

 Latitiulc, 420 22' 48.3" N. 

 Directors: W. C. Bond, 1839. 

 G. P. Bond, 1359. 



J. WiNLOCK, 18GC. 



Edward C. Pickering, 187G. 



Annexed to Harvard College; projected in 1815; ground acquired in 

 1842; instruments set up in 1844-'4S; a central tower and dome, two 

 wings, M'ith a small dome on tbe western wing-. Here it was that G. P. 

 Bond discovered in 1848 tbe seventb satellite of Saturn (Hyperion), 

 and in 1850 tbe dusky interior ring inside tbe brigbt rings of tbat planet. 

 Among tbe cbronograpbs, tbis observatory possesses tbe original in- 

 strument of W. C. Bond, mounted in 1850. 

 Instruments : 



(a) Meridian circle: Makers, Trougiiton & SiMMS (glasses by Al- 

 VAN Clark & Sons); diameter of circles, oO incbes; divided to 5'; 

 eacb circle read by 4 microscopes to 0.1"; aperture of objective, 8^ 

 incbes; for observations of tbe sun, aperture employed, 8^ incbes; 

 magnifying jiower ordinarily employed, 300 to 350 diameters, (a') East 

 transit circle, by Troughton & Simms ; diameter of circles, 48 incbes ; 

 divided to 5' ; eacb circle read by 4 microscopes to 0.2" ; aperture of 

 objective, 41 incbes. 



{h) Meridian transit instruments : One made by Herbst, of Pulkowa; 

 aperture, 2f incbes; magnifying power, up to 200 diameters, {h') 

 Large pbotometer, mounted in tbe meridian, for comparing images of 

 stars during transit. 



(c) Equatorial instruments : One made by Merz ; aperture of object- 

 ive, 15 incbes; magnifying powers of eye-pieces, 100 to 2,000. (c') 

 West equatorial, by Alvan Clark & Sons ; a})erture, o^ incbes. 



{d) Spectroscopes : Tbree, described in vol. viii of tbe Annals of tbe 

 Observatory. 



(e) Photometers and other subsidiary apparatus : One Zollner pbo- 

 tometer, and several pbotometers of otber kinds. 



(/) Chronographs : Two spring governors, by W. Bond & Son ; one 

 small barrel cbronograpb. 



[g) Clods : One mean time; maker, Bond, 394; one sidereal; makerSj 

 Frodsham, 1327 ; Bond, 312. 



