ID: 
1332
Maker's Name: 
ALLBRIT
Where made: 
England

A planimeter was used to measure  areas on maps or plans or graphs. The perimeter of the area of interest was traced around by the stylus on the tracer bar and the reading on the rolling drum was then scaled to provide the answer in appropriate units. Finding the area underneath the graph of a function is equivalent to finding its integral.

This one was used in the Zoology Department.