Page:Scientific Memoirs, Vol. 2 (1841).djvu/50

38 it might not conceal the stirrup situated behind it, and is represented by itself in fig. 4. In the westerly view, fig. 3., the small notch in the stirrup into which the weight-carrier fits, is merely indicated; while in the southern view, fig. 6., it is shown as fitted into the notch, and placed on the magnet bar, and the two half kilogrammes it is to bear are suspended from its points.

Fig. 1. presents a view of the suspender, with the screw and suspension thread, from the west. $$A\;A$$ is a board fixed to the ceiling; $$B\; B$$ two parallel wooden rods glued to it, between which a slider, $$D\, D$$, may be moved from east to west; it is supported by two projecting parts, $$C\; C$$; the brass nut, $$E$$, through which the elevating screw passes in a direction from east to west, is fixed with screws to the slider; $$F$$ is the screw head at the western extremity, which in this figure hides the screw; $$G$$ is the suspension thread attached to the screw.

Fig. 2. represents a view from the south, of the same suspender, with the screw and thread. $$A\; A$$ here, is the longitudinal section of the board fixed to the ceiling; $$B\; B$$ is the rod glued to this board on the north side; $$C\; C$$ the support of the slider; it is furnished at the edge with a scale, for the adjustment of the slider; $$D\; D$$ the longitudinal view of the slider, to which the copper nuts $$E$$ and $$E'$$ are fixed with screws. Through these nuts passes the elevating screw, the head of which is represented by $$F$$. This screw passes through the nut $$E$$, and is kept in its place by the nut $$H$$. Near to the second nut $$E'$$ the screw changes into a smooth cylinder which passes through a smooth aperture of the nut $$E'$$/ At the end of the thread of the screw the suspension thread $$G$$ is fastened, and lies in the grooves, in which it continues to the centre, and there falls perpendicularly, bearing at its lower end the stirrup of the magnetometer. When the thread is to be raised, the nut $$H$$ is loosened, and the screw turned by the screw-head $$F$$ into the required position.

Fig. 3. presents a view, from the west, of the vibrating portion of the magnetometer. It consists of two eyes, $$A\; A$$, of which the posterior is concealed in this figure by the anterior. The lower end of the thread $$G$$ is fastened to a pin fixed under them. To this part of the magnetometer belongs also the torsion-circle $$B\; B$$, upon which the stirrup $$C\; C\; C\; C$$ rests; the magnet bar $$D\; D$$, and the mirror-holder $$E$$, with two frames $$F\;F$$, $$H\;H$$, and the clamps $$K\;K$$, serving to receive the mirror. With the exception of the magnet bar, which alone weighs 1700 grammes, and of