Pro Calculo - 1920

"I have been trying to find a picture of the calculator / adding machine that I have just inherited. I do not see it in your great site. 

It is in it's original postal envelope with a postmark from 1922. The postal envelope also has a pat. Jan 1919.  The sender was Wholesale Import and Export House George Krammerer Agent in the Bowery NYC. The mailing envelope has 2 hand held "pro calculo" with metal pens and are each incased in a snake skin leather type cover that they slip into. I have enclosed pictures. Would you know what year this is from. I am interested in selling them."


Source: Beth Stone

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