68 H. J. Grayson : 



The motive power and running gear have Ijoth received 

 careful consideration, so as to reduce noise and wear and tear 

 to a mininiuni. Each grinder and the sHcing discs are inde- 

 pendently operated, and can be instantly thrown in or out of 

 action by the mere push or pull of a conveniently placed 

 handle. There are no idle running bands or belts ; motion 

 being communicated as required from a single overhead shaft 

 by a specially designed clutch. 



The net gain from these advantages, of which I give only 

 the briefest outline, is that it has been made possible, as the 

 result of actual trial, to slice a specimen suited for examina- 

 tion under the micz'oscope — i.e., a section having an area of 

 about one inch in diameter, and reduced to a thickness of less 

 than .001 inch — the whole operation — slicing, grinding and 

 mounting, occupying not more than 10 minutes — the specimen 

 in question being a piece of granite. On no other machine, 

 with which I am act|uainted, is it possible to do this work 

 within so short a time. 



With regard to economy in working, the machine costs for 

 motive power, running say 6 hours, not more than 6d. The cost 

 for diamond powder, for slicing purposes — also deduced from 

 actual trial — for a well charged disc, is not more than Is. With 

 this charge 95 slices, averaging lin. in diameter and cut from about 

 20 different varieties of rock, ranging in hardness from granite 

 to soft sandstone, were sliced without a re-charge of the disc. 



Provision has been made, in addition to ordinary rock slicing, 

 for cutting and grinding crystals to definite faces, and also for 

 cutting and grinding parallel plates to a precise thickness. 



More recently, a further modification has been made, 

 adapting the machine to the cutting of serial sections, as, for 

 example, in the case of a fossil imbedded in a piece of rock, 

 etc. The method was first devised and described by Professor 

 Solhis, of Oxford University, in the Transactions of the Royal 

 Society of London for 1903. Professor Sollas obtained a special 

 grant from the Royal Society for the construction of his 

 machine, which was designed by the Reader of Mechanics — 

 Mr. Jervis Smith, of Oxford University. 



After reading Professor Sollas' description of this machine, I 

 saw at once that, with no modification of the machine 



