As iron shrinks about ¹/₁₀ of an inch to a foot, brass shrinks ⅕ of an inch to a foot and steel and aluminum shrink about ¼ inch to the foot you must allow this much for shrinkage in making your patterns. Type-metal is an alloy which expands on cooling and this is a useful thing to know. You will find a formula for making it in Appendix L, and all of the appendices from A to N contain detailed information on a variety of subjects that should be very helpful when you are making your model.
CHAPTER VI
HOW TO PATENT YOUR INVENTION
With your model in such shape that it shows what your invention is and what it will do you are ready to apply for a patent, or letters patent as it is technically called, by those versed in the art.
What a Patent Is.—The term letters patent comes from the Latin litteræ patentes which means open or disclosed, as against the French lettre de cachet which means closed or secret.
A letters patent, or patent as it is called for short, is exactly what its name implies and that is a disclosure of your secret and for this disclosure of a new and useful invention on your part the government agrees to give you a monopoly, that is the sole right to make, use and sell it as you please for a term of 17 years.
But the government does not live up to its agreement with the inventor and the invention and patent for it are never securely yours until it has been tested in the United States Supreme Court and its judges have handed down their opinion in your favor. But since there is no better protection than a patent at the present time of course you will have to get one.
Choosing a Patent Attorney.—The next hardest thing to do after making a working model of your invention is to get a patent attorney to take out a patent for you.
I don’t want to infer by this that it is hard to find a patent attorney for on the contrary they are as numerous as sharks in the sea and twice as voracious, but a patent attorney who really understands his business and will take an interest in your affairs is as scarce as a pseudotriakis microdon,[3] unless you are backed by unlimited funds, and then you may get service.