Operation of Test Churns 83 
Churn tests.—The first butter factories or cream- 
eries were managed upon what is known as the 
cream-gathering system: that is, the cream was 
raised and skimmed upon the farm, and it alone 
taken to the factory. It was soon found that the 
eream varied considerably in the percentage of fat 
that it contained, and, moreover, that a consider- 
able amount of milk could be mixed with the 
cream without being detected by ordinary means. 
In other words, the managers of factories learned 
that cream as it came to them was even more 
variable in its percentage of fat than whole milk. 
In all of the earlier factories the cream was paid 
for simply by measure, and it became necessary to 
devise some means of making an equitable division 
among the different patrons, and of protecting the 
factory from loss. To do this, what was known 
as test churns were devised. At the time of 
gathering the cream, a small sample (a pint or 
quart) of each patron’s cream was taken in a sep- 
arate vessel. These were taken to the factory 
and churned separately in small tin cans, and the 
butter made up from each. The butter-producing 
power of the single pint or quart was taken as a 
measure of the butter value of the whole amount 
of that patron’s cream, and the proceeds were ap- 
portioned accordingly. This method was much more 
just than a simple measure of. the cream, but it 
was very cumbersome. It required delicate manip- 
ulation in order to make all of the little pats of 
butter of the same water content, and the small 
