ASTRONOMICAL OBSERVATORIES. 



257 



lar railway. The opening in the dome is 18 inches wide, 

 and has three doors which slide over each other, and are 

 moved by cords passing over pulleys. 



8HABOX OBSBEVATOET. 



The equatorial was made by Merz and Son, of Munich? 



It was ordered in 1842, and arrived in 1846. The ob- 

 ject-glass has a clear aperture of six and a third inches, 

 and its focal length is nearly nine feet. It has a microm- 

 eter with a large number of eye-pieces magnifying from 

 85 to 456 times. The hour circle is 9 inches in diameter, 

 and the declination circle is 13 inches. Clock-work is 

 attached to the polar axis, giving to the telescope a uni- 

 form motion, and keeping a star apparently at rest in the 

 field of view. The entire expense of this instrument was 

 $1833. 



This observatory is also furnished with a meridian 



