2UC 



THE MICROSCOPE. 



to be cut is put into the tube e, and is l-aised or depressed 

 by the screw/; whilst, before cutting, the curved piece of 



Fig. 133.— Topping's Section Cutting Machine. 



metal k should be firmly pressed against it by the screw c. 

 This instrument, if fastened to the edge of a bench or 

 table, is always ready for use. The knife employed may 

 be one constructed for the purpose ; or a razor ground flat 

 on one side. 



Method of making Sections. — If the wood be green, it 

 should be cut to the required length, and be immersed for 

 a few days in strong alcohol, to get rid of all resinous 

 matters. When this is accomplished, it may be soaked in 

 water for a week or ten days ; it will then be ready for 

 cutting. If the wood be dry, it should be first soaked in 

 water and afterwards immersed in spirit, and before cutting 

 placed in water again, as in the case of the green wood. 

 The wood, if too large, should be cut so as to fit tightly 

 into the square hole, and be driven into it by a wooden 

 mallet; if, on the contrary, it be round, and at the same 

 time too small for the hole, wedges of deal or other soft 

 wood may be employed to fix it firmly : these will have 

 the advantage of affording support, and if necessary, may 

 be cut with the specimen, from which they may afterwards 

 be easily separated. The process of cutting consists in 

 raising the wood by the micrometer screw, so that the 



