Postal Rates In 1910-S

I have often heard the term "double rate" used to explain the usage of a 4 cent stamp on an envelope. What type of mail required double rate?

Was it strictly weight based or were there other conditions where it was required?

To paint with a broad brush, yes, "double rate" = "double weight".

Thank You John.

It's what I thought. So it was for first class 2 ounce mail.

Then is it safe to assume that the 3 cent rate was for 2 ounce circular mail ?? My questions are in the context of how the stamps were used in Schermack mailing machines. If that is the case, some companies really pushed that limit using 1 cent stamps.

In the teens, 3 cents is more likely the 3 cent WWI letter rate of Nov 2, 1917-June 30, 1919.
Circular mail (3rd class), is going to be 1 cent per 2 ounces in the 1910's.

Specific examples would be more practical, perhaps.

Stamps such as this are known from Babson Brothers envelopes with information on Edison Phonographs from around 1910.



All known stamps have been hand stamped because the envelope was to large for a machine cancel. From the one known cover which has a fold, it appears they were folded prior to being fed through the Schermack machine and then stuffed and sealed.

That is only an assumption. The envelope may have been folded after it had been received and opened.