THE MICROSCOPE. 21 



? elections. 



A Method of Making and Mounting Transparent 

 Rock-Sections for Microscopic Slides. — The following method 

 of making and mounting transparent rock-sections tor the micro- 

 scope, was taught me several years ago by the late Mr. Arthur 

 Pratt, of Glasgow. And, with a few exceptions, which will 

 be noted, the method I use is essentially that followed by Mr. 

 Pratt. 



The first step is of course to get a suitable piece of rock, say, a 

 fragment of Trap or Basalt. 



This should be broken as thin as possible, and to do this, having 

 struck off a fragment from the parent rock, or boulder, take it be- 

 tween the fingers and thumb of the left hand. Hold one edge on 

 the rock from which it was struck, or any hard stone which may be 

 convenient, and strike it a sharp blow with the hammer, fair on the 

 opposite edge. If this is well done thin fragments, about one-eighth 

 of an inch thick, will fly off. 



These fragments ought to be rough-hewn, on the spot, so long 

 as there is plenty of material to work from, and for this purpose I 

 use a pair of cutting nippers such as are used for cutting wire. With 

 a little practice, any one will soon become expert in using them. 

 Take a thin fragment of the rock in the left hand, and with the 

 nippers work round it, clipping off the superfluous angles until a disc 

 of about seven-eighths of an inch in diameter is formed. With a 

 little experience this can be done in less than a minute. My practice 

 is to take four such discs, of each kind of rock from which I wish to 

 make sections; two to ensure getting a finished section, and two to 

 meet the requirements of friends. 



I also take a thin piece of the rock one inch and a quarter 

 square, or thereabouts, as a cabinet specimen, and for comparison 

 with the finished section. This specimen should, if possible, 

 show a weather-worn face, although it is not always possible to get 

 a specimen in this state, especially if it is taken from a mine, or 

 quarry. The specimens ought to be labelled on the spot, and the 

 most convenient way to do this, is to have with you a quantity of 

 elliptical or circular gummed labels, about three-quarters of an inch 

 in diameter. If the specimen is taken from a Trap Dyke, the thick- 



