388 ASTKOXOMICAL OBSERVATORIES. 



Draper's private observ^atory at ilastiiigs, N. Y., by Alvan Clark 

 & Sons, is of the finest coustrnction. Tli« object-glass of the GA-iiich 

 equatorial was also made by the Glares, and is provided with a port- 

 able njouuting- made by Warner & Swasey. The 4 inch comet-seeker, 

 made by Alvan Clark & Sons, hiis a focal length of 33 inches. The 

 rdys fall on a reflecting prism, and are bent into a horizontal plane. 

 T]^e eye of the observer, moving in azimuth while the telescope is in 

 altitude, can cover the whole sky. The motion is effected by turning a 

 craidv. This was bought on Professor Newcomb's recommendation. 



The photoheliograph is mounted south of the transit house. The 

 transit instrument determines the axis of the photoheHogra])h, and this 

 is also used as a collimator for the transit. The 6-incli Kepsold merid- 

 ian circle was delivered in 1881^, after having been inspected by Pro- 

 fessors AUWERS and Krueger, of Berlin. The declinograph was 

 made under the supervision of Dr. Johann Palisa, of Vienna, to fit 

 either a 12-inch or a C inch equatorial. The universal instrument made 

 by Eepsold consists of a telescope containing a prism, into which the 

 rays of light are reflected. Its aperture is 2.15 inch. The horizontal 

 circle reads by two microscopes to two seconds, and the circles are 10 

 inches in diameter. This is a perfect geodetic instrument, and together 

 with a G-inch equatorial and a cljrouometer can be easily packed for 

 astronomical expeditious. There are several chronometers made by 

 Negus, and a thermometric chronometer by C. Frodsham. The most 

 important of the minor instruments are the fihir micrometer for the 

 36inch telescope by Fauth & Co., the duplex micrometer by Grubb, 

 and a star spectroscope made by Brashear from designs of Mr. 

 Keeler. Plans for a large solar spectroscope are being worked out 

 by Professors Holden and Langley. The other instruments are a 

 delicate sphereometer by Fauth & Co. ; resistance coils ; galvanome- 

 ters; a disk photometer ; spectroscopes; a lever trier of refined con- 

 struction ; and an engine for measuring photographs, scales, etc., made 

 by Stackpole & Bros., from designs of Professor Harkness. 



»The meteorological instruments are: Self- registering rain-gauges, 

 wind-gauges, barometers, and a number of thermometers. There is a 

 complete set of apparatus for registering earthquakes, provided by the 

 Cambridge Scientific Instrument Company, consisting of a horizontal 

 seismograph with clock and driving plate, the clock being started by 

 an electric contact at the beginning of a shock, and the two rectangu- 

 lar components of the horizontal motion then registering on a moving 

 l)late; a vertical seismograph to register vertical motions on a dial 

 plate; a dupfex pendulum seismograph to give independent records on 

 a dial- plate, the pencil being free to move in any azimuth; and a chro- 

 nograph, which is set in motion at the beginning of an earthquake ami 

 recortls its duration upon a clock. The start" of the observatory con- 

 sists of Prof. Edward S. Holden, director and chief astronomer; 

 Samuel W. Burnham, James E. Keeler, John M. Schaeberle, 

 and Edward E. Barnard, assistant astronomers; and C. B. Hill, 

 secretary, librarian, and occasional observer. 



Early in 1880, Professor Holden made contracts with the Southern 

 Pacific and other railroad companies for supplying tinu^. from the ob- 

 servatory by automatic electric signals. This regular time service, of 

 which Mr. Keeler has charge, has been in operation since January, 

 1887. A great i»art of the apparatus used in this service forms an in- 

 tegral part of the observatory's equipment. The system which has 

 thus been introduced has been of great service to that particular sec- 

 tion of the country, as well as to the railroad companies. 



