would reach the other extremity of the pipe.

8. The art of using the diamond for cutting glass has
undergone, within a few years, a very important improvement. A
glazier's apprentice, when using a diamond set in a conical
ferrule, as was always the practice about twenty years since,
found great difficulty in acquiring the art of using it with
certainty; and, at the end of a seven years' apprenticeship, many
were found but indifferently skilled in its employment. This
arose from the difficulty of finding the precise angle at which
the diamond cuts, and of guiding it along the glass at the proper
inclination when that angle is found. Almost the whole of the
time consumed and of the glass destroyed in acquiring the art of
cutting glass, may now be saved by the use of an improved tool.
The gem is set in a small piece of squared brass with its edges
nearly parallel to one side of the square. A person skilled in
its use now files away the brass on one side until, by trial, he
finds that the diamond will make a clean cut, when guided by
keeping this edge pressed against a ruler. The diamond and its
mounting are now attached to a stick like a pencil, by means of a
swivel allowing a small angular motion. Thus, even the beginner
at once applies the cutting edge at the proper angle, by pressing
the side of the brass against a ruler; and even though the part
he holds in his hand should deviate a little from the required
angle, it communicates no irregularity to the position of the
diamond, which rarely fails to do its office when thus employed.

The relative hardness of the diamond, in different
directions, is a singular fact. An experienced workman, on whose
judgement I can rely, informed me that he has seen a diamond