D. Greene—Paper Dome for an Astronomical Observatory. 55 
Art. VI.—Description of a Paper Dome for an Astronomical 
Observatory ; by Professor DAscom GREENE, Troy, N. Y. 
AN astronomical observatory has recently been erected for 
the Rensselaer Polytechnic Institute, through the liberality of 
Mr. E. Proudfit of this city. In maturing the plans, and super- 
vising the erection of the building, I have introduced an 
improved method of constructing revolving domes, a brief 
account of which may not be without interest. 
While making the preliminary inquiries, I ascertained that 
a dome of the dimensions required, constructed in any of the 
methods in common use, would weigh from five to ten tons, 
and require the aid of cumbersome machinery to revolve it. 
It therefore occurred to me to obviate this objection by mak- 
ing the frame-work of wood, of the greatest lightness consist- 
ent with the requisite strength, and covering it with paper of a 
quality similar to that used in the manufacture of paper boats; 
the principal advantages in the use of these materials being 
that they admit of great perfection of form and finish, and give 
extreme lightness, strength, and stiffness in the structure,— 
prime qualities ina movable dome. A contract was accord- 
ingly made with Messrs. E. Waters & Sons, of this city, the 
well-known builders of paper boats, for the construction of the 
dome, and they have carried out the undertaking with great 
skill and success. 
Spanning the entire d se are firmly attached to the 
sill and kept in a vertical position by means of knee-braces. 
The sill and girders are of season i ormer being 
ed pine, the 
84 inches wide by 34 thick, and the latter each 4$ by 3 
inches. 
The paper covering of the dome is made in sixteen equal 
sections, such that when set up side by side, their bases on 
the sill, and their extremities meeting at the top, they form 
a co e hemispherical surface. e e-work of each 
section consists of three vertical ribs of pine each 3} inches 
in wi nd 8 of an inch thick, one at each side and one 
midway between, and meeting at the apex. The paper was 
stretched over this frame-work as follows: 
