260 THE NORTHERN MICROSCOPIST. 
MACHINE FOR CUTTING AND GRINDING 
ROCK SECTIONS. 
ACHINES for this purpose are generally expensive ; but, like 
most other machines, can be efficiently simplified when their 
action becomes known. For this purpose, I give a sketch and 
particulars of one that has been made for me, and can fairly say 
that it does its work with as much ease and celerity as could be 
wished. 
A is a strong wooden box without bottom, with the front side 
taken off to demonstrate the details inside, consisting of a solid 
wooden fly-wheel (B) of sufficient thickness to take a tolerably 
broad strap, and its shaft (C), which at one end is fixed into a 
piece of wood stretched across the bottom to receive it, and at the 
other end is the handle. This wheel turns a small drum also of 
wood and its shaft (D), on which is attached horizontally an ordinary 
tinned iron disc, about nine inches in diameter, fixed on like a 
circular saw by large washer and nut. It is safer to have the 
upper part of the shaft (D) made of brass, as the perfect adjust- 
ment of the disc constitutes the main thing. 
In one corner is fixed an iron standard, running the entire 
depth of the box to ensure its perfect rigidity, turned to receive 
one end of the clenching rod which should rotate freely and 
evenly. To the clenching iron (K) is attached an iron plate (L) 
by two thumb-screws (HH). Between these two screws and 
towards the bottom is another thumb-screw, which does not pene- 
trate the plate (L), but acts as a check to prevent that plate from 
dipping downwards and imperfectly holding the stone, which is 
placed between these two plates in front of the disc (E). By 
means of this a glass slip can be securely fixed without slipping, 
and if the stone to be cut is delicate, it can be cemented to the 
slip and a slice taken off zz situ ready for grinding. 
Round the disc is placed a moveable guard box of tin, to 
prevent the water and dirt from flying on to the operator, and 
preserving the utilized emery, which comes in use when grinding. 
For working the machine—get the specimen as square as con- 
venient, and clench it at the required angle between the plates in 
front of the disc. With the right hand turn the handle, and 
hooking the little finger of the left round the clenching rod, thus 
exerting gentle, even, and continuous pressure of the stone against 
the disc, at the same time dropping at intervals some ved emery 
powder stored between the finger and thumb. ‘The emery is thus 
taken round with the disc, and is pressed into the soft metal, thus 
