60 Machine for Microscopic Writing. 
the height of about 3 inches ; the upper end of this piece is 
split to receive another horizontal arm {a\ at the free end of 
which is the diamond {d)^ with the point downwards, and so 
adjusted that it is in the axis 
of the combined levers. 
As, however, the end to 
be attained is the registering 
(not of all the movements 
made, but) of those move- 
ments only which form the 
writing or design, the opera- 
tor is provided with the 
means of suspending, resum- 
ing, or continuing the action 
of the diamond at pleasure. 
Two uprights (1, fig. 3 and 
fig. 4) are fixed near opposite 
edges of the upper stage 
each having a horizon- 
tal pivot (or they may be 
connected by a horizontal 
piece with a knife edge up- 
wards) : on the pivots (2), 
(or the knife edge) is hung 
a thin flat plate of brass (3) 
of sufficient size to hold a 
glass slip of the ordinary 
dimensions, 3 in. by 1 in. ; to 
one of its ends is fixed a 
steel wire (4) with a screw 
cut upon it, on which a small 
brass weight (5) with an in- 
terior screw is placed: near 
one of the lateral edges of 
the plate two small pins (6, 
fig. 4) project a little above 
its surface : near the opposite 
edge is a spring (7, fig. 4), 
which presses the glass slide 
against the two projecting 
pins, while one of its ends 
comes up to the extremity 
of a screw (8), which can be adjusted so that the centre of the 
glass be brought under the diamond point {Z) : when the slide 
has been placed on the holder and properly adjusted, the weight 
(5) is to be moved on the screw till it accurately balances the 
