which will lie found the followinp;, tn-wit: 



One eight-inch Hrashear retlecting telescope; 



Two four-inch Zeiss equatorial refracting telescopes mounted on 

 heavy tripods affording a very firm base. They are equipped with 

 circles and driving gears and each is supplied with a full set of eye- 

 pieces; 



A binocular telescope with a pair of two-inch objectives, mounted 

 upon a hea\}' tripod and having a set of one-hundred diameter eye- 

 pieces; 



An unusual telescope in the Observatory is a two-inch refractor. 

 Its objective lens is ground from quartz. It is intended primarily 

 for photographic work in connection with spectrum analysis but it 

 may also be used for visual purposes: 



Two Bausch and Lomb prism binocular field glasses. One has 

 a pair of two-inch objectives and a magnifying power of twelve diam- 

 eters. It has brilliant illumination and affords a beautifully distinct 

 view when used on objects such as the Pleiades or Hyades. The 

 other has twenty-five millimeter objectives and gives a magnifying 

 power of six diameters. It affords the greatest field of view possible 

 and is excellent for embracing extensive regions of the skies. Both 

 instruments may be used in the hands or upon tripods: 



A coelostat with a ten-inch plane mirror rotated on an equatorial 

 mounting by clockwork, at such a rate that it will keep a beam of sun- 

 light, reflected from its silvered surface, on a second stationary plane 

 mirror. This instrument is used in connection with the spectroscope; 



A Bausch and Lomb spectroscope; 



Apparatus for projection purposes in illustrating lectures and 

 demonstration work at the Observatory consisting of the following, 

 viz: 



1. Three stereopticans with electric arc and nitrogen incan- 

 descent lamps, with a full set of objectives for different forms of 

 projection work; 



2. A scientific lantern for experimental work; 



3. A moving picture machine. 



Thirty mechanical lantern slides which illustrate the cause and 

 show the effects of many of the celestial phenomena such as eclipses, 

 tides, time, transits, variable stars, revolution of the Earth around the 

 Sun and the Moon around the Earth, the Solar system with the revo- 

 lutions of all the planets and the orbits of comets with the develop- 

 ment and action of their tails; 



A siderial clock, two eighteen-inch globes, one of the Earth, the 

 other of the heavens, a set of weather instruments and an illuminator 

 for perforated star maps. 



Important among the exhibit material is a model of the Moon 

 made of plaster-of-paris, forty inches in diameter. Its detail is copied 

 from direct observation with the telescope. By illuminating the globe 

 with a powerful electric light, the phases of the Moon can be pro- 



52 



