I will be the first one to admit I know nothing about this item so I am leaving it up to the Maritime collectors. This is what I found on the Internet. This is a propeller pitchometer which was patented by J. Chapman and J. Hunter around 1896. It was used by inspectors to determine and verify the proper pitch of a ship’s screw propeller. Everything seems to be in working order. I have taken plenty of pictures so please take the time to study them and ask any questions that I hope I can answer. If my information is wrong please tell me as I like to know the history of items I sell. It definitely needs a good cleaning. I will leave this up to the collector as I am sure they know how to clean brass. Please feel free to ask any questions, thank you for taking the time to view my auction.