Some count it as the 15th, some as today, the 18th, but shouldn't every day be cow appreciation day?
This item from the Libraries' trade literature collection in the National Museum of American History Library seemed appropriate, no matter when you want to celebrate.
You can read a more detailed post on cream separators here.
De Laval Separator Co., De Laval Cream Separators, Farm and Dairy Sizes, 1913.
—Elizabeth Periale