Inventors, especially those of little experience in working out new ideas, and obtaining patents, are likely to be led into some errors which they might easily avoid. A common one is the supposition, that ill-built machinery will do to demonstrate a principle. Experimental machines are often so poorly constructed, that instead of satisfying the mind of the experimenter, they make him skeptical of success by their imperfect working. The principle may be perfectly sound, and would prove so, if properly tested, yet the idea is either abandoned, or a new and more perfect machine has to be constructed,and the money already expended thrown away. It is'an old maxim that what is worth doing at all is worth doing well; and nowhere is the truth of the saying more strikingly demonstrated than in the performance of an experiment. An experiment is utterly valueless unless performed with care, and under all the conditions ultimately to be fulfilled. Tinkering should be, by all means, avoided; and nice and good workmanship secured, whenever possible to attain it. It costs more at first, but it is more economical in the end. A second mistake is the supposition, that almost any one possessed of some legal knowledge can properly prepare specifications, and claims for a patent. This is one of the most fatal mistakes inventors make. The proper preparation of the papers for an application requires not only knowledge of the patent laws, but matured judgment, based upon large experience. To claim more than can properly be claimed, is to insure the rejection of the application. To claim less is to force the client to obtain by reissue what he might have obtained at first. Even the most skillful and experienced men may err in judgment on this point; how much more likely to blunder is one who has had little or no experience. Some inventors attempt the prosecution of their own claims. Most of these come to grief. Not that the Patent Office willingly refuses to recognize their claims, but that all legal procedure is, and from its nature must be, attended with the observance of technicalities, to neglect which is to jeopardize their rights and cause the applicants much annoyance. A third mistake on the part of those inexperienced in obtaining patents, is the supposition that, because a patent is rejected on the first application, it is a gone case. Now, the fact is, that perhaps one third of all the patents issued are rejected on first application, and yet, upon amendment of claims, or, in some cases, argument to show that amendment is not needed, are subsequently allowed. This ought not to discourage the inventor from proceeding with his application, but it frequently does discourage him. Many a good thing has been dropped in this way for want of pluck to prosecute claims on which an excellent patent might have been obtained.