40 



he were using a standard rule; and when -the pattern is completed 

 it will be found to be larger in all its dimensions, just in proportion 



IN.PER FT. SHRINKAGE 



Fig. 82. 



as the extra length of the shrinkage rule makes it greater than 

 the standard rule 



OIL STONES. 



As before stated, new planes, chisels, and other edged tools, 

 if of the best quality, are always sold ground and sharpened, ready 

 for use. When used, however, they soon become dulled, and must 

 then be resharpened, and be so kept as to have a smooth, keen 

 cutting edge, in order to do good work and to work rapidly. The 

 method employed for doing this is the same for all edged tools, 

 whether ground and sharpened on one side or on both sides. 



Oil stones are used for plane-irons, chisels, and all flat and 

 straight-edged tools; and oil slips, having rounded edges, for 

 gouges, and for all tools having curved edges. They are made of 

 different sizes, and may be found of many and widely different 

 qualities. The best known and most widely used oil stones in this 

 country, and perhaps in the world, are the "Washita," of which 

 the "Lily White Washita" brand, being carefully selected, are the 

 most even in grade and quality, and are the best-adapted natural 

 stone for woodworkers' tools. 



The Arkansas oil stones are claimed to be the hardest and 

 finest oil stones in the world. They are composed of nearly pure 

 silica in the form of minute crystals interpenetrating one another. 

 and ditfe,r from the Washita only in the minuteness of the crystals 

 and in their more compact arrangement. They are consequently 

 very much harder and cut hardened steel more slowly than coarser 

 grades of stone, but impart a finer and smoother edge to the tool. 

 They are used by wood-carvers, engravers, watchmakers, and others 

 using tools that require a very fine edge or point. They are 

 expensive, and should be used carefully with equal parts of sperm 



fc- **' " 



oil and glycerine. 



