Figs. 204 and 205 show about the simplest construction for a wooden dome. They were made from the working drawings of the dome of the Woman's Building at the Cotton States Exposition at Atlanta, in 1895, Elise Mercur, architect.
This dome was 41 ft, 6 ins. in external diameter and hemispherical in shape. The shell is formed of 32 ribs built up of 4 pieces of 1x8 boards, cut to the curvature of the dome, breaking joint and well spiked together. These ribs rest on a circular plate built of 6 pieces of 2x10 plank, and abut against a circular ring at the top. Horizontal pieces were cut between the ribs at intervals of about 3 1/2 ft.
The strength of the shell was materially increased by the drum surrounding the base of the dome. Fig. 206 shows the manner in which the dome was supported over the square space below. The framework on two sides was supported by interior partitions and on the other two sides by Howe trusses, one of which is shown in the figure.
Fig. 207* shows a section through the wooden dome over the Nicolaikirche, Potsdam, Prussia, the external diameter of which is about 72 feet. No description was given of the construction, but it is probable that the etched plates, P P, extend all around the dome, and that there are perhaps three trusses similar to the one shown in the figure, extending across the dome in two directions, and that the outward thrust at the base is taken care of by iron rings.
•From the "American Architect." of May 29, 1897.
Wooden domes can also be constructed by braced ribs, built up similarly to the steel ribs shown in the following illustrations.
Fig. 208. - Dome of Buffalo Savings Bank.