847. Saw set gauge, for crosscut saws.











848. This came from the inside of a 9 volt battery.




A month or two ago Popular Science magazine had a short article about how to make a small safe for valuables from a battery. I would never use one as a safe, but I opened one because I hadn't before seen what was inside. I had mentioned the battery safe to a friend of mine last week and a day or two later he showed me a post card that he had received from Popular Science warning against doing this project, since the batteries could possibly rupture.

A much better idea is to make a book safe, this is a great project, I made two of them to give as Christmas gifts.










849. Placido'’s disc for astigmatism, used by an eye doctor to measure the regularity of the cornea, thanks to phisick.com for use of the photo.











850. Visgage, oil viscosity tester, patent number 2,609,682.



Larger image of the instructions

As seen in the link, Google now features a patent search, I've tried it a few times and it seems to work well.










851. Stanley No. 30 angle divider











852. Bunnell pen register, records an incoming Morse code message.

















































Last week's set is seen below, click here to view the entire post:








More discussion and comments on these photos can be found at the newsgroup rec.puzzles.