An early Plus Adder by Bell Punch

This is an early Plus Adder made by Bell Punch. It is almost identical to the Petometer designed by Guy Bazeley Petter of Petters Ltd. in 1933. Bell Punch bought the patents and manufacturing rights in 1936 and produced it in this form until about 1940. It was then redesigned, and was in production in many variants until at least the late 1960s.
For more information on this and other calculators in my collection please visit my web site:
www.jaapsch.net/mechcalc/
0:00 Introduction
0:55 Addition
1:22 Sterling currency
2:11 Clearing
2:34 Serial number and patents
3:21 Early model versus later model
4:22 Complete rollover
4:45 Outro

[@GrumpyTim]

It's really nice to see an early Plus Adder, I'd not seen one like that before. Cheers Jaap.