I went through Chambers’s Encyclopedia from A to Z. Read all about acids and paper, metals and metallurgy, dies and molds. I studied the history of locks and lockmaking, poring over the pictures of locks and their escutcheons⁠—all kinds of locks and keys, door locks, padlocks, combination locks, nothing was neglected. I read a most interesting paper on picklocks and lock picking by a famous lockmaker of London. I followed the history of explosives from gunpowder down to nitroglycerin. I found a passage that told clearly and concisely which explosives did the greatest damage and made the least noise. What a mine of information! I was fascinated. I studied guns and pistols, drills and saws and files, braces and bits and drilling machines of high and low pressure and fast or slow motion.