Blast from the past!!

Came across this very accurate, mercury, developing thermometer I used to use a great deal to "boil" some of my 35mm film in a very fast developer in those days called Ergol..you could push and push up the speed of your film to the point where you could take shots in a theatre or circus with no flash at all.
Very touchy stuff though, accurate temperature and timing was vital on development. Brought back memories:)