183 
these globes must be hollow, and sufficiently buoyant to float 
the ring from the lower surface. 
Fig. 2. 
Is an enlarged view of LV, and the letters and references 
are the same as in Fig. I . 
Fig. 3. 
Is a modification of the lower valve LV, when the space 
M is filled with oil instead of mercury. 
AC. Is an air cylinder attached to a hemispherical valve 
closing the concave end of XT', as in Fig. 2, but to ensure 
vertical action there is added — 
GP. A guide-plate in XT', through which passes — 
GR. A guide-rod attached to the top of the hemispherical 
valve LV. 
Fig. 4. 
Is an enlarged view of U V and the globular chamber which 
surrounds it. Xhe tube CX in Fig. 1. is omitted, and the 
aperture to which it may be attached is left open. 
Xhe apparatus (thus represented in a skeleton plan) must 
be properly supported on a stand with some means of com- 
municating motion to the piston rod. 
Xhis may be efiected by a simple lever, and more effectually 
if arranged to give a parallel motion. 
My suggestion is to attach it to the apparatus proposed by 
Mr. James White, by which a continuous rotatory motion 
produces the necessary alternate perpendicular motions essen- 
tial to its action. Vide Century of Inventions, Plate 7- 
Assuming that every provision has been made for working 
the machine, but that no mercury or oil has been introduced 
into it, we shall commence by supposing that PP, the piston, 
has been brought up to the top of the cylinder. 
Xhe aperture at CX in the globe being open, mercury 
must now be poured through a funnel into the hole in the 
centre of the ])uinp-plate PP', from which it will run down 
through XX', LV, and fill tlie tube of the piston rod PP, and 
