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acter of the stone cut. Hence it is well adapted to the whetstone 
industry for here the rock is not always one great block of stone, 
in fact it is hardly ever that, but is almost always a mass com- 
posed of many small pieces which have been cemented together 
with plaster of Paris and sand in the saw bed and thus offers a 
somewhat varying resistance to the action of the saws. This is 
an important advantage over a “‘ Screw-feed ’’ gang in which the 
saws are moved down regularly by machinery at a rate propor- 
tional to the hardness of the stone. In the latter gang the saws 
become choked if hard spots are encountered, although they work 
well enough where the texture of the stone is perfectly homogen- 
eous. 
The cutting is produced by moving the saw gang backward 
and forward over the stone and freely supplying it with sand and 
water, the actual cutting of the stone being caused by the constant 
rubbing against the rock of these iron bands or saws in which the 
hard grains of sand become imbedded. As the sand is coarser 
than the grains of the stone, the latter are gradually scratched 
away. 
THE Sanp Pump. Until recently it was necessary to em- 
ploy workman, not only to watch the several gangs but also to 
supply the same with the sand necessary for sawing. One pair of 
gangs would usually furnish one man with plenty of employment. 
At that time the necessary water was supplied from a perforated 
pipe extending across the entire bed above the stone and from 
which the water was continually dripping. In thus trickling 
down it would first carry the sand to the saws, and then wash 
out the fine powder produced by the sawing. Recently, however, 
they have introduced the sand pump in the factory by means of 
which the water after carrying the sand to the saws and doing its 
work there, is drained from the groove surrounding the gang- 
saw and pumped up again to drop from the pipe above the bed. 
Thus the same sand and water is used over and over again mak- 
ing it possible to dispense with the extra workman, and enabling 
one man to watch an entire bank of saws instead of but one pair 
as formerly. 
