282 HISTORY OF ASTRONOMY. 



accept/ General Steven Yan Kensselaer kindly offered 

 a donation of several acres of land near the northern 

 -limit of the city, affording an excellent site for the 

 contemplated building. Mrs. Blandina Dudley, a lady 

 distinguished for her wealth and liberal spirit, gave 

 toward the building the sum of $13,000. ContributiQns 

 were received from several gentlemen of the city, in- 

 creasing this sum to $25,000. The building was com- 

 menced in the spring of 1853, upon a plan designed by 

 Professor Mitchell, and the late Sears C. Walker, and 

 was erected under the supervision of Professor Perkins. 



The ground-plan of the building is in the form of a 

 cross, 84 feet in front by 72 feet in depth. The central 

 room is 28 feet square ; the east and west wings, which 

 are designed for the use of* the meridian instruments, are 

 each 23 feet square, and provided with the usual open- 

 ings in the meridian. The north wing is 40 feet square, 

 divided into a library room, two computing rooms, 'and 

 other small rooms for the magnetic apparatus for re- 

 cording the observations. The equatorial room, which 

 is in the second story, is of a circular form, 28 feet in 

 diameter, the tower revolving upon iron balls. 



The main pier for the support of the equatorial was 

 commenced six feet below the bottom of the cellar, 

 with its base, 15 feet square, resting on a bed of con- 

 crete and rubble 16 inches in thickness. The size of 

 the pier was gradually reduced to 10 feet square at the 

 level of the cellar, and thus continued upward without 

 further variation. The whole is built in the most sub- 



