vintage Monroe adding machine
I remember seeing these adding machines (in fact this one haha) in my dad's office when growing up. My dad worked for a natural gas company. All the meter men brought their charts back to the office and used the adding machines to calculate gas flow. These machines were ubiquitous in field offices in the oil and gas industry from the 1920's all the way through the 1960's. Even a little more recently, I grew up in the '70s.