Old brass exposure meter

When my Brother in England died, amazing friends went through his whole house, putting aside all the special personal belongings - most of which had, in fact, belonged to our parents - and shipped 12 boxes of amazing things to me in Calgary. I will forever be tremendously grateful for their unbelievable kindness! I now have pretty well all my Father's old cameras that he used in a lifetime of passion for photography. My friends also sent me all his old cameras (and two little Brownie cameras that had belonged to me), many of his old photo albums, all his photographic Awards, and this old, brass exposure meter. It is about 2" tall - and I love it. Did a bit of a Google search late last night and found several that were similar, but I need to do more careful reading so that I better understand how it was used. My Father died in 1976 at the age of 69. How I wish I had had all the following years to talk about photography with him, even though we lived on opposite sides of the earth.