202 
EDWARDS, ON FINDERS. 
of the fic'd by the stage movements when the indicator is 
about to be used. This ruling of the stage and circular piece 
of glass can, however, be done away with, by using a card of 
the same dimensions as the stage on which the two lines are 
drawn with a fine pen, and a circular portion in the centre 
made removable by a hinge or otherwise. 
The indicator itself is a slip of paper the same size as the 
slide, viz., three inches by one, as seen in fig, 1, and has two 
Fig. L 
lines drawn across it, one inch from each end, which are 
graduated in fiftieths of an inch. At one tenth of an inch 
from each side, a line is drawn connecting the others, and 
these are also graduated in fiftieths of an inch.* By this 
arrangement the horizontal lines, which are numbered from 
left to right, bear the figures 0 to 50 ; and the perpendicular 
ones, in which they run from top to bottom, from 0 to 40. 
On one end of the paper is a space for the number of the 
slide, and on the other, one for the description of the object 
mounted thereon. The blank space of paper between the 
scales is cut out, and after writing (in the parts assigned to 
them) the number and description of the object, the indicator 
is fastened to the glass slide with its face to the opposite side 
to which the object is ; so that the graduations can be read 
through the glass, which serves to preserve both them and 
the label from being soiled. 
When we wish to use the indicator, we have simply to 
place the slide on the stage; and when we find an object 
that we wish to register, we bring it to the centre of the field 
of vision, and then observe what numbers the two lines (as 
a a' and b h\ in fig. 2), ruled on the stage or card cut. 
For instance, in the figure they cut 40 in the horizontal 
scale, and 15 in the perpendicular one; and, supposing the 
The United States inch is the same as the English. 
