ASTRONOMICAL OBSERVATORIES. 



259 



feet. It rests upon a pier of masonry which rises 11 feet 

 above the floor of the room. The hour circle has a 

 diameter of 18 inches, with verniers which read to one 

 second of time. The declination circle has a diameter of 

 30 inches, with verniers which read to five seconds of 

 arc. This instrument is moved by clock-work, and has a 

 variety of magnifying powers from 44 to 1640 ; also a 

 filar micrometer, and a double-image micrometer. A 

 movable platform runs around the room at the height of 

 eight feet from the floor, and gives easy access to the 

 object-end of the telescope and the graduated circles. 

 This telescope cost 800 sterling. In the same room is a 

 clock with mercurial compensation by Molineux, of Lon- 

 don, which is attached to a solid pier unconnected with 

 the floor or walls. 





TCSCAJ.OOSA OBSERVATORY. 



The west wing is 16 feet square, and is occupied by a 

 transit circle made in 1840 by Simms, of London. Its 

 telescope has a focal length of five feet, and an object- 



