C 25 1 
positions, and it is nearly in that manner that the 
common churn is worked. A second consideration 
is to simplify the machine and save friction as 
much as possible, and this could not be done more 
effectually than by adopting the drill method of 
turning the churn-stick. Cogs might have been 
used for this purpose, but they would very consid¬ 
erably have added to the complexiiess aifd friction 
of the work, as well as to its liability to be impaired. 
A third consideration of essential importance is to 
what degree dhe power of the machine is to 
be multiplied; and this is to be governed entirely 
by the force that is to work it and the resistance 
to be overcome. The size of the roller has been 
calculated on this principle. Its circumference is 
about thirty inches, which is about the length of 
each stroke that the operator will naturally 
make : So that every stroke will make a complete 
revolution of the dasher, and throw its extremi¬ 
ties 30 or 40 inches through the milk. It will be 
found also on trial that the operation is not too la¬ 
borious for a person of ordinary strength, and in¬ 
deed much easier than the common mode of churn¬ 
ing. If it had been required to adapt the machine 
to persons possessing but half the ordinary strength 
of men, the diameter of the roller would have been 
doubled ; but it is evident that then one half of the 
effect would have been lost, for every stroke would 
ill such case have made only half a revolution of the 
dasher according to the axiom that what is gained 
in power is lost in time or space.. All the use of 
