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ASTRONOMICAL OUSEEVATOKIES.
Draper’s private observatory at Hastings, N. Y. , by Alvan Clark& Sons, is of the finest construction. The object-glass of the CJ-iuchequatorial was also made by the Clarks, and is provided with a port-able mounting made by Warner & Swasey. The 4-inch comet-seeker,made by Alvan Clark & Sons, has a focal length of 33 inches. Therays fall on a reflecting prism, and are bent into a horizontal plane.The eye of the observer, moving in azimuth while the telescope is inaltitude, can cover the whole sky. The motion is effected by turning acrank. This was bought on Professor Newcomb’s recommendation.
The photoheliograph is mounted south of the transit house. Thetransit instrument determines the axis of the photoheliograph, and thisis also used as a collimator for the transit. The 6-inch Kepsold merid-ian circle was delivered in 1881, after having been inspected by Pro-fessors Auwers and Krueger, of Berlin. The declinograph wasmade under the supervision of Dr. Johann Palisa, of Vienna , to fiteither a 12-inch or a 6 inch equatorial. The universal instrument madeby Repsold consists of a telescope containing a prism, into which therays of light are reflected. Its aperture is 2.15 inch. The horizontalcircle reads by two microscopes to two seconds, and the circles are 10inches in diameter. This is a perfect geodetic instrument, and togetherwith a 6-incli equatorial and a chronometer can be easily packed forastronomical expeditions. There are several chronometers made byNegus, and a thermometric chronometer by C. Frodsiiam. The mostimportant of the minor instruments are the filar micrometer for the36-inch telescope by Fautii & Oo., the duplex micrometer by Grubb,and a star spectroscope made by Brasiiear from designs of Mr.Keeler . Plans for a large solar spectroscope are being worked outby Professors Holden and Langley. The other instruments are adelicate 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., madeby Stackpole & Bros., from designs of Professor Darkness.
The meteorological instruments are: Self-registering rain-gauges,wind-gauges, barometers, and a number of thermometers. There is acomplete set of apparatus for registering earthquakes, provided by theCambridge Scientific Instrument Company, consisting of a horizontalseismograph with clock and driving plate, the clock being started byan electric contact at the beginning of a shock, and the two rectangu-lar components of the horizontal motion then registering on a movingplate; a vertical seismograph to register vertical motions on a dialplate; a duplex pendulum seismograph to give independent records ona 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 aridrecords its duration upon a clock. The staff 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 1886, Professor Holden made contracts with the SouthernPacific and other railroad companies for supplying time from the ob-servatory by automatic electric signals. This regular time service, ofwhich Mr. Keeler has charge, has been in operation since January,1887. A great part of the apparatus used in this service forms an in-tegral part of the observatory’s equipment. The system which hasthus been introduced has been of great service to that particular sec-tion of the country, as well as to the railroad companies.