GRAVITATION AS AFFECTED BY TEMPERATURE. 
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on turning one way on a vertical axis, it rises ; on turning the other way, it falls, and 
in so doing clamps m x by pressing hard on it. The horse-shoe electro-magnet, E 
(figs. 9 and 10), can be raised or lowered to operate m x or m 2 . By this torsion-head 
arrangement the suspension can be set and clamped, wherever desired, in vacuo. 
Fig. 8. Shows the tubing for evacuating and washing out with oxygen ; also the tube and funnel mounted 
on the window. The weight of this tube and funnel is carried by a wire attached to the main 
scaffolding. Part of the water-jacket, but no lagging, is shown at the lower end of tube AB. 
4. The Small Mass ( m , m) System .—The suspension is seen in the core of tube, AB 
(figs. 6, 7, 9, 10). The beam and the vertical wire, b, attached to its centre are of thin 
wire. The mirror, Si, is enclosed in a case of thin foil and is so attached to the vertical 
wire that a fine inclination up and down can be made at will. The long copper or 
