OIL OF SESAMUM. 
139 
the upper stone to the surface of the lower one, where, being ground, 
it gave out the oil. This flowed over the lower stone into a reservoir 
below it. Here ended the process of expression ; but another com- 
menced, the intention of which I could not so well understand : it 
was probably connected with some mode of purifying the oil. I men- 
tion it chiefly as an example of the simple, and what may perhaps be 
called, domestic methods, sometimes in use with the Chinese, to 
diminish the degree of manual labour. A quantity of oil recently 
taken from the mill, and contained in a wide shallow vessel, was 
continually agitated by a large copper pestle, with which a lad gently 
struck its surface. The fatigue that would otherwise have arisen 
from the weight of the pestle and uniform motion of the arm in using 
it, was prevented by the following very simple contrivance : A small 
bow of bamboo being fastened to the ceiling immediately over the 
vessel containing the oil, the pestle was fastened to its string in the 
manner shown in the wood engraving. Thus suspended, it received 
from the slightest touch an adequate impulse ; whilst the elasticity of 
the bamboo gave it the necessary recoil. 
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