H. Goadby on making wet Preparations of Animal Substances. 21 
slip in a direction ae to the former cut: thus the two sides 
of the glass are made 
Keep the glass still oe the guide board and removing the 
square, apply the gauge; cut the whole length of the glass and 
you have the width of the slides. Now turn the squared end of 
the glass just cut into the space at g,, pressing it firmly against 
the angles of the guide board, (which must also be made e quite 
true,) place the gauge against the guide board in its former posi- 
tion, cut the glass transversely, as shown by the dotted line, and 
you have the length of the slide; and in this way cut up the 
remainder of the slip of glass as far as it will yield slides of the 
proper length, 
In like manner the spaces d and e, in - guide board, give the 
length of other slides, the width of which has been cut previ- 
ously with other gauges adapted to ie purpose. By this ar- 
rangement of the cutting board one gauge is alone required to 
cut the width and length of a slide of any given dimensions. 
From the foregoing description it will be obvious that the ganges 
must be first made, the length of the spaces in the guide board 
determined by their assistance, and they must be cut in it before 
it be affixed to the cutting board. 
Grinding the Glass.—Unuless the slides are to be covered with 
paper, the sharp, rongh edges left by the diamond cut should be 
removed by grinding the glass. This can be accomplished on 
a perfectly flat stone of sharp grit with water; the process is 
greatly facilitated by the addition of emery, but ‘the best tool, in 
my experience, is a plate of soft pewter. 
My plate was formed in a mould made for casting the pewter 
plates on which to engrave music ; its outside measure, therefore, 
corresponds to the size of a printed page of music, but it is 4 an 
inch thick, aud weighs 14 lbs. It is important that the wit ah 
made quite flat, and every care should be taken to keep t 
so. Soft pewter is desirable because it contains a much shoei 
quantity of lead than the hard, in which tin preponderates. ‘The 
metal is used only as the vehicle of the cutting material, which 
isemery. ‘The latter, in time, becomes thoroughly impacted in 
the metal, so that it will cut with the assistance of water alone, 
and the wear of the plate is too trifling to be estimated. When 
in use it should always be charged well with “superfine” —s 
and water. Finer emery has no cut; and coarser tears the glass. 
ger the glass slide to be ground at an angle of about 45°, 
the outer line of the edge may alone touch the plate of 
Moar grind by a quick, light, circular motion—to and from, 
the corners—until the line be straight and beveled ; 
ap e the position of the glass to aes the realy, ead line 
same preage be now hold the 
the edge smooth. By beveling the 
