CONCLUDING REMARKS. 47 
The slice must now be ground down to that degree of thinness which 
will permit its structure to be seen by help of a microscope. To facilitate 
this part of the grinding, the lapidary will find it advantageous to, fix the 
glass in a groove made in a small piece of wood, of which half inch thick 
deal will answer the purpose. The groove in the wood should be a little 
less deep than the thickness of the glass, and the wood itself need not pro- 
ject more than half an inch beyond each side of the glass. 
A lapidary, by attending to the above directions, will find no difficulty 
in reducing any piece of petrified wood to that degree of thinness sufficient 
to render its structure visible ; and any one, even without the aid of the me- 
chanism employed by the lapidary, may accomplish that object by attend- 
ing to the following directions. 
The position of the fibres of the wood having been ascertained, let a thin 
piece be chipped off by a blow of a hammer, in a direction perpendicular to 
the length of the fibres. Let the chip thus obtained be cemented to any 
small bit of wood by common lapidaries’ cement (a compound of 1 part 
bees’ wax, 1 part pitch, 4 parts rosin, 16 parts of a mixture of brick-dust 
and whitening), to enable the operator to hold it firmly while the grinding 
is going on. That side of the chip which approaches nearest to a perpendi- 
cular to the length of the fibres, must be ground flat, by giving it a rapid 
circular motion with the hand, on a piece of sheet-lead lying horizontally on 
a table, and supplied with a little emery, size No. 1., moistened with wa- 
ter. When the emery ceases to act, the muddy matter remaining may be 
removed, and a fresh portion of emery applied; and this must be repeated 
until the surface of the chip has become perfectly flat. ‘The sheet of lead 
must then be removed, and a piece of flat sheet copper substituted, and the 
surface of the chip ground as smooth as may be, by flower of emery, freed 
from its coarser parts. The surface may then be polished by friction with 
crocus or rot-stone, on a transverse section of any soft wood. 
When the polishing is finished, the chip must be detached from the 
wood to which it was cemented, and the polished surface cemented by Ca- 
nada balsam to a piece of plate-glass, in the manner above described, and 
then ground thin, and polished as before. 
