Marbel Blood Cell Calculator
This thing has been in my collection for a long time. They were intended to make life of clinical lab assistants easier - one of the chores in the old days was to do blood counts - you would put a plate with a smear of blood from a patient under the microscope, and start counting according to a pre-defined procedure, all the different kinds of blood cells. This little apparatus was intended so you could do it blind, without taking your eyes of the microscope objective. In that sense it is not really a calculator, just a counter with 8 different registers.It is clear that it was used - there are lots of traces of sticky tape, and a strip of paper with the different types of blood cells marked in black marker is stuck to the top of the machine.
It does look a lot prettier however, with the originally intended card on the machine, which has colour pictures of the different types of cells you should encounter.
This is nr. 21622, and if anyone wants to contact the company, all the info is right there...
All in all, a funny little mechanical contraption.