PROCEEDINGS OF SOCIETIES. 121 
I reply that I do not claim any merit either for originality 
in proposing, or for priority in using this plan, which indeed 
is likely enough to have occurred to many persons who have 
been much occupied in preparing and mounting objects for 
the microscope; as, however, I thought it not unlikely that 
this method might be unknown to some persons present, and 
judged also that the place and the occasion were proper, I 
ventured to mention it. Perhaps I may be allowed to add 
that I have specimens of injections prepared and mounted in 
this way as long ago as 1850, and though at first I had 
recourse to this method but rarely, being uncertain about its 
permanence, | have now for several years mounted ‘ injec- 
tions’ almost exclusively in this way, either in cells or 
without them, as the thickness of the specimen required. I 
have also a pretty extensive series of sections of the roots, 
woods, and barks of the Materia Medica, prepared and 
mounted in this way, with the advantage of well-secured ob- 
jects, without falsification of the optical characters of the 
. structures.” 
Mr. Wenham said—“ Having had considerable expe- 
rience in working glass, for optical purposes, I may state, 
that I frequently make use of hard steel with turpentine for 
rapidly reducing to form pieces of glass chucked in the lathe. 
I take a three-square saw-file, and grind away one of the 
faces as it loses its keenness and becomes worn; this con- 
stantly leaves two sharp serrated edges, which are applied to 
the revolving piece of glass, ‘ overhand’ or in the way that 
a spoke-shave is used, supporting the file on the T rest, 
which is raised nearly level with the top of the work. 
I also employ turpentine for drilling glass. If the drill is 
made of the hardest cast steel, and hardened by quenching 
in dilute sulphuric acid, without being afterwards tempered, 
I can drill an eighth-inch hole through a plate of glass one 
inch thick in about one minute. The dmill should be 
sharpened on both sides, so as to cut either backwards or 
forwards, and is best worked by the Archimedean drill-stock. 
Most glass is somewhat softer than hardened steel, but if 
the attempt be made to drill glass dry, a very intense heat is 
generated on the cutting edge, which destroys the temper 
and softens a very minute superficial film of the steel, which 
is then rubbed away, leaving a round edge unsuitable for 
cutting. The turpentine does not act in any peculiar way 
upon the glass itself, but its extreme fluidity and penetrating 
quality enables it to bathe the end of the drill during its 
rapid rotation, and by thus keeping it cool its hardness is 
maintained. For glass-turning I prefer old turpentine, as 
