Dalton Adding Machine, Comptometer Box, and Wall Calendar, Lewis Walker Company Office, 1925

A number of interesting details are visible in this detail from the center section of this 1925 photo of the Lewis Walker Company Office.

First, a Dalton Adding Machine is positioned on its own stand in the foreground. The machine was capable of printing calculations onto the paper from the roll that's positioned on top.

Secondly, a case for a Comptometer—"the first commercially successful key-driven mechanical calculator"—is lying on the desk located behind and to the left of the Dalton machine. The label on the outside of the Comptometer box says, "Comptometer (Pronounced like thermometer). Felt & Tarrant Mfg. Co., Chicago, U.S.A. Adds. Divides. Multiplies. Subtracts."

Finally, an advertising calendar hanging on the wall at the back of the room confirms that the photo was taken in February 1925 and suggests that the location may be Pittsburgh or somewhere else in western Pennsylvania. The advertisement on the calendar says, "Brown & Zortman Machinery Company, machinists supply company, machine shop equipment and supplies, Pittsburgh, Pa. February 1925."

See also the full version of this photo and a close-up of the man seated at the desk.