OP THE UNITED STATES. 307 



ground, and may be diminished to about one foot and a liall 

 at tlie top. 



The south front has three windows, the ca^t and west 

 front each one. and the north front two. The door is in 

 the place of the north eastern window. In tlic middle of 

 eacli of the windows, the wall projects inward, in form of a 

 semicircular pillar two feet in diameter, <7, a, a, tlie top ot 

 wiiicl). together with the windnw slielf, is covered with one 

 Hat hewn stone, fastened in the wall, and three feet al)0ve 

 the level of the floor. This admits any moveable instru- 

 ment to be placed under the window for observation, even 

 in the meridian of the transit, and the wintlows and shutters 

 can be closed outside of it, without disturbing it. 



'IMie windows are all five feet broad and nine feet high in 

 the clear, which will admit observations as near to the /enith 

 as is otherwise practicable with moveable instruments, and 

 give sufficient freedom in the azimuth, not only for all cir- 

 cum-meridian observations, but also for corresponding alti- 

 tudes. 



The windows and the shutters slide by counterpoises en- 

 tirely below the window seat, in the recesses b. b, made 

 for the purpose in the outside of the wall, and covered by a 

 wooden frame projecting sufficiently to shelter them all. 

 The covers c, c of this frame form the outer part of the win- 

 dow seat, and move on hinges ; by which means tliey open 

 or shut the recess with its frame, and support the windows 

 and shutters, when these are closed. 



The middle of the observatory is occupied by the transit, 

 which rests upon two solid stone pillars ;;, p elevating it near- 

 ly seven feet al)0vc the floor. Their inner sides arc perpen- 

 dicular, and thirty inches from each other; the three outer 

 sides are ta])ered towaids the top. Their bases are about 

 two feet square, and the tops about ten inches, l^pon their 

 flat tops tlie supports of the transit are fastened, and on the 

 inner sides the counterpoising spring rollers, as has been de- 

 scribed in the proper place, and may be seen in fig. 4, 



