ASTRONOMICAL OBSERVATORIES. 3G9 



carried into active operation the system of time service on a scale then, 

 and probably still, as regards the systematic distribution of time to rail- 

 roads, tlie most extensive in the country. The observatory is the stand- 

 ard of time for a large portion of the railroads connecting tlie Atlantic 

 and the Mississippi. It is better known by its investigations in solar 

 physics, to which the director has given his i)rincipal attention for the 

 last ten years. 



Instruments : 



{b) 2Leridian transit instruments: Makers, Troughton & Simms ; 

 aperture, 4 inches ; magnifying power, 150 diameters. 



(c) Equatorial instruments : Makers, Fitz, reworked by Clark; aper- 

 ture of objective, 13 inches ; magnifying powers of eye-pieces, 50 to 

 1,200; equatorial carries a 12-inch flat mirror by Clark at south end of 

 its polar axis; also, position filar micrometer, polarizing solar eye-piece ; 

 apparatus for projecting solar image ; eight other subsidiary pieces. 



{(1) Spectroscopes: One employing large Eutherfurd grating; one 

 with small grating ; one 2-prism spectroscope ; apparatus for using large 

 equatorial as collimator, etc. 



(e) Photometers and other suhsidiary apparatus: A variety of ther- 

 mopiles, used in connection with a Tho3IPSON reflecting galvanometer; 

 large Bunsen photometer ; small portable heliostat, etc. 



(/) Chronographs : One of Bond's pattern, built by Hamblet. 



{g) Clods : Mean time; two by Howard, both break-circuit : sidereal; 

 one by Frodsham, break-circuit. 



(/i) Chronometers : Mean time ; one by Frodsham : sidereal ; one Frod- 

 SHAM, break- circuit. 



(?) Miscellaneous : One reflecting telescope of 6J-inch aperture, spe- 

 cially used for obtaining an image, projected any size without the em- 

 ployment of any enlarging lenses; one Foucault siderostat and a large 

 number of special pieces of ai>paratus for the study of radiant heat. 



The observatory has never issued any regular series of annals; for 

 abstracts of the results of its work reference must be made to the 

 Comptes Eendus de I'Institut de France, to the Memoirs of the U. S. 

 National Academy, to the pages of the American Journal of Science, of 

 the Aunales de Chimie et Physique, Wiedemann's Anualen, and to 

 various foreign and domestic scientific journals. 



Electric appliances for the distribution of exact time, automatically 

 and contiuuously to points outside the observatory. 



Amherst, Massachitsetts. 



The Lawrence Observatory of Amherst College, 



Longitude from Washington, 18'" 1.8' E. 

 Latitude, 12^ 22' 15.G" N. 

 Director : David P. ToDD. 

 H. Mis. 170 24 



