50 ’s GRAVESANDE’S COLUMN 1928 (29, 1194) I-'ig. 53, 57
Replica of column, made in 1928 by De Boer.
Overall height 1,380, base side 560.
The mahogany column is in four sections; the triangular base is of oak. The long
central section has a slot into which attachments may be locked. There is an alternative
column top and various wooden nuts and washers. The experiment supported
by the column in the illustration shows forces acting on a wedge, see Cat. 54.
’s Gravesande (1748) IV, fig. 5, illustrates the column, and the rest of the plate
the attachments;
Attachments 3/4 18th C.
1) Section ofcolumn with holes for turn-pegs, made of mahogany with inset boxwood
screw; ’s Gravesandeyi748) IV, fig. 5.
s| Mahogany block (overall length 210) with provision on one side for hanging
tackle cords, and on the other for mounting a rod pendulum and a plumb-bob
pendulum to find the centre of inertia of the rod;
’s Gravesande (1748) IV, fig. 9, block; X, fig. 6, pulley; XVI, fig. 5, pendulum.
3;) Mahogany bar (overall length 800) with three small brass hooks in one side.
4) Mahogany bar (overall length 135) wkh a brass hook;
’s Gravesande (1748) IV, fig. 6.
5) Mahogany bar (overall length 200) with brass pulley;
’s Gravesande (1748) IV, fig. 7.
Inv,
51 PARADOX OF THE ANGLED LEVER ^ l8th c (nil). Fig g |
An angled lever of beech (overall length of arms 200 and 250) is used in conjunction
with a board of mahogany (area of face 210 x 62), faced with boxwood to reduce
friction, which is mounted in the slot in the column. A slit is provided in the board
so that the arm of the lever can swing freely. There is a small brass hook at the top
of the face. A tackle block carrying three brass rollers is attached by wires to a brass
weight, and is held against the board by the lever; see the engraving reproduced in
fig- 54- The rollers and weight, G and Q, are balanced by a weight P on the inclined
arm of the lever. When the positions are reversed, as in the bottom figure, the greater
force P is apparently balanced by GQ. There are, however, three forces acting on G
in this new position.
’s Gravesande (1748) XIV, fig. 2, 3, 4.
52 PERCUSSION APPARATUS 3/4 18th C. . (1094) Fig. 55, 57
Mahogany, compartmented box (3o||x 205 x 60) containing a variety of apparatus
for percussion experiments.
1) Two brass frames (79 x 37 x 14) into which lead weights may be fixed to vary the
mass, and into which a choice of percussion heads may be screwed; ’s Gravesande
(1748) XXVIII, fig. 4.
Six cylindrical lead weights to fix into the frames; op. cit. fig. 5.
gH| Five ivory heads that screw onto the frames, to show the effect of profile on
indentation. Each head is domed or conical with different apex angles; op. cit. fig. 7.
4) Mahogany tray to hold clay (75 x 60 x 25) on a bracket with two brass bolts in
slots for fixing onto a vertical board attached to the column. The clay receives the
impressions of the heads ; op. cit. fig. 8.