Monthly Microscopical"! 
Journal, May 1, lt569. J 
of Ohjed-glasses for the Microscojoe. 
297 
on a level with the top of the work, and an old triangular saw-file, 
kept sharp on one side only by repeated applications to the grind- 
stone, was then held on the rest, so as to attack the revolving 
glass slantways, or spokeshave fashion, with plenty of turpentine. 
By these means the glass was quickly reduced to form, so as to 
fit the template; and the ridges left by the file were swept away 
by means of small leaden laps, fed with emery and water of de- 
creasing fineness. The polish was obtained by a rubber of willow- 
wood, cut crossways of the grain, used with crocus and water, and 
at last a lump of beeswax with very fine crocus was employed for 
the final polish. 
For working small concave lenses as nearly as possible to their 
final form, a great deal of accurate and skilful turning is required. 
For this delicate work steel tools are quite unsuited, and diamond 
points are invariably used. The common practice of mounting 
these has been to solder them with brass and borax, by means of 
the blowpipe, into the end of a steel tube about the size of a watch- 
key, leaving a hole behind to prevent the diamond from being 
blown out during the fusion ; but I have never found this method 
secure for small splinters. The brass has really no affinity for the 
diamond, but rather tends to avoid it ; and this is frequently only 
held in by the glaze or flux. The loss of several diamonds 
induced me to abandon this practice, and since adopting the fol- 
lowing mode I have never lost one. I take a piece of copper wire 
about V^th of an inch thick, and drill a shallow hole in the end, of 
the size and depth required to contain the diamond, thus. Fig. 1 ; 
[>□ 
a piece of steel is turned out with a bell-mouth, and hardened, as 
shown by Fig. 2. This is spun rapidly in the lathe, a drop of oil 
is applied, and the end of the copper rod containing the diamond is 
pressed hard in, at the same time giving it a slight rolling motion. 
Speedily the copper is compressed tightly round the diamond, as in 
Fig 3, which becomes very firmly imbedded in the soft metal ; and 
if the operation is carried too far, the copper rises over the point 
and completely buries the splinter. 
By mutual abrasion, diamonds rapidly grind each other away, 
and two mounted in wires in this way may be kept mutually to a 
sharp point, by chucking one in the lathe and using another as 
a turning-tool. In employing these diamonds for turning glass, 
no particular directions are needed ; they seem to cut rather better 
if the work is kept shghtly moist. 
