H. Gioadby on making wet Preparations of Animal Substances. 29 
cut another circle within the last and so proceed cutting circle 
within circle as long as the diamond can be adjusted to cut, and 
the glass will then present a series of concentric circles. 
Take a center punch and screw it point upwards in a bench 
vice; place the center of the innermost circle on the point of the 
punch, and get an assistant to hold the glass while the operator 
takes another center punch and placing its point wpon the glass 
immediately over the point of the lower one, strikes the upper 
punch lightly with a hammer, not to break but to pound the 
glass lying between the two punches. Presently a small hole 
will*be made ; now bring the broken edge of the glass upon the 
lower punch, continuing the pounding motion until the hole be 
sufficiently enlarged to admit of using the ‘‘plane” of the small - 
and light hammer with which the punch has been struck. At 
this stage of the process, the use of the upper punch should be 
discontinued, and the operator holding the glass himself, keeping 
an edge of the hole always supported on the lower punch while 
he lightly taps it with the plane of the hammer, not attempting 
to remove the circles as cut, but rather tracing the hole from the 
center to the circumference, (like making a cross in the glass,) and 
if it have been cut, not scratched, large pieces will fall out as soon 
as they have room enough, and the entire operation be finished 
in less time than it takes to describe it. 
In like manner, an oval cell can be made as easily as a round 
one. ‘The glass should not be cut into shape to form the ouwler 
dimensions of the cell until the central hole be made, as it is 
likely to break. Upon this plan a hole of any size can be easily 
cnt in a plate of glass of any dimensions. Sir Charles Babbage 
told me that he once communicated this plan to a glazier, who 
employed it most extensively in punching holes in squares of 
glass to form the bottom plates of street gas lamps, for the trans- 
Mission of the gas pipe. 
_ T have already remarked that the above plan of cell-making is 
limited to glass one-eighth of an inch thick; my wants fre- 
quently required cells full as deep again; I could cement two or 
more shallow ones together and thus build up any required depth, 
but they look heavy and I prefer therefore to cut them out of 
plate glass of the proper thickness. When in London I could 
obtain the services of Mr. Dennis to cut anything that I required, 
at any time; but in this country, at this moment, I am altogether 
town upon my own resources. To meet my wants I have 
contrived a small, portable, and most efficient apparatus, by means 
of which any lad can cut cells as well as [ can, and with this 
machine my son has cut for me the best cells I have ever had. 
~ It consists of a, a, (fig. 7, A,) an iron support with three arms 
and a square plate at the lower end of it, cast in one piece. "0, 
Vertical beveled wheel working c, a horizontal beveled wheel 
