By the terms of the contract, the whole subway, with all rolling stock in perfect order, becomes the property of the City of New York in fifty years; and before that time the operating company,

of which Mr. Belmont is the head, must pay back to the city the $35,000,000 advanced it for building the structure, with 5 per cent interest, in regular annual installments.

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UNDREDS of patents issued by the Patent Office each year, and received by the inventors with joy, are really not worth the cost of their patenting. The inventor learns this in the end, but often not until he has wasted considerable money, devoted valuable time, and worked or waited patiently for months and years in vain. Along with these worthless patents, other hundreds of patents of great value, are issued each year, by the aid of which many a man rises to prosperity and affluence. In considering what makes the difference, it is well to remember that a patent is nothing magical. It is merely a right granted by the Government, authorizing the patentee to forbid other people making, selling, or using a certain thing defined in the patent.

What Makes a Patent Valuable?

The patentee makes his profit ordinarily by permitting others to make,

sell, or use the invention, and by exacting toll therefor. But if no one wishes to make, sell, or use it, what then? The mere fact that an inventor has discovered a new way of doing a thing, does not make his invention valuable. The new way may be a cumbersome or expensive way, or may be one of several ways, all equally good. It must be something that people will pay money for the privilege of using. In the last analysis, the value of a patent is based on the public demand for the patented thing.

Of course it may be possible, by advertising or by clever salesmanship, to create a demand where no demand existed before. So, also, a patent on a cumbersome way of doing a thing may have a sale value if it constitutes an alternative of some better way that is itself monopolized. In such a case it may be worth money to the owner of the older monopoly to buy the new though poorer way in order to continue his monopoly and prevent reduction of his profits by

competition. These, and other seeming exceptions that may arise, are really but different manifestations of the principle that the value of a patent depends upon the degree to which people may desire to exercise the invention it covers. The patents covering inventions which are new and useful in the sense of the patent law, but which are not demanded by trade, art, or manufacture, are the ones that are worthless-not worth the cost of printing, much less worth the government and attorneys' fees which the inventor must pay for obtaining them. How to distinguish such from the inventions that may have patentable value; how to manage them profitably and escape mistakes that too often prevent the inventor from realizing that value, will be considered in this and subsequent articles.

The profit to be derived from a patent depends upon other things besides those mentioned. It depends upon the judgment shown in adopting a suitable policy for handling the patent. It depends upon the capital and energy with which it is exploited. It depends greatly upon the business ability with which the article is offered upon the market. It may depend much upon its opportuneness. A good golf ball invention is worth much more in the United States to-day than it would have been twenty years ago, and is probably worth less than it would have been five years ago. The value frequently depends upon the ownership or control of a system of other patents in the same line of business. The inventor of an improved detail in a type-setting machine can hardly utilize his invention unless he is free to make and sell a complete machine in which it is embodied. He may be unable to do this, either from lack of facilities or capital, or because essential parts of the machine are covered by patents to others. Practically his only profitable course in such case is to procure a patent for the invention and sell it to some maker of such machines. This does not mean that he will receive only a small sum for it, nor that he must take a price dictated by the purchaser, for the invention may relate to a very important detail, and there may be several competing makers each anxious to secure it; but the inventor must in this

way or some other connect his patent with the existing patents that dominate the system.

Let not a man despair simply because he is poor. If the invention is good, and if the patent is properly drawn and sagaciously sold, he may receive a rich return. There is probably no easier way to wealth for the ordinary citizen, no door to comfort that opens more readily, than that afforded by an intelligent use of United States patents. It is the elevator by which those who know how may rise, while others toil up the stairs. But the elevator must be used with care. A patent is property; to sell it advantageously requires business ability of the same high order that is required to dispose of any property advantageously. A patent will no more sell itself than will a house and lot-except at a sacrifice. The patentee will be hampered to greater or less extent by his lack of capital, by his inexperience in negotiation, by his remoteness from business centers; but so he would be in in any business transaction. Indeed, while everyone can see and judge a house and lot, the value of a patent is visible sometimes only to the inventor. The usefulness of it may have to be explained; the public and the trade may have to be educated. Moreover, while there is always a market for real estate, the market for a patent is very limited. Only those who can use it, either in their business already established, or in a business to be established, are available as buyers; and it will have value to them, as a rule, only in proportion to the extent to which they can utilize it. Therefore a patent has most value to a concern doing a large business. Attendant circumstances-such, for example, as the existence of but one prospective purchaser-may prevent the patentee from easily obtaining a price commensurate with the value of the patent to the purchaser; but that is only another problem for the salesman. The inventor should consider all these things before spending money toward getting the patent. If the invention is meritorious, and if it can probably be covered by a patent giving a good monopoly, with prospect of a good demand, the inventor may go ahead with corresponding confidence that he will ultimately get his

money back, and as much more as the character of the invention and his own circumstances and ability will warrant.

The First Necessity

Before procuring the patent, the first thing to do is to make the invention. That seems an absurdly simple remark; but it is surprising how many people there are who, having conceived of a useful result, desire a patent before they have really devised any way of accomplishing it. One such person came to the writer for a patent on an improved method of preventing collisions of electric cars. He proposed to have each car automatically send to the motorman of the other car an electrical warning of its approach. This was surely a neat way of preventing collisions; but the manner in which the signal was to be generated and sent, and received on the approaching car, remained uninvented. He wanted a broad patent on the happy result; others who understood electricity might devise the particular means.

It is not necessary that the inventor should work out the complete mechanical details of his device before applying for a patent; still less need he construct a working specimen; but he should think out his plan with sufficient completeness so that a person skilled in the particular art to which the idea relates could construct the device and make it work without further invention, relying only on the instructions of the inventor and the general or special knowledge which such a person is presumed to have.

too extensive (when their personal interests are involved), the courts have found it necessary to require such testimony to be supported by something additional. This simple precaution may enable the true first inventor to prove his priority in a case where he would otherwise wholly lose the benefit of his invention merely through lack of witnesses to prove that his conception existed at a date earlier than the date his opponent can prove. Such a disclosure to witnesses is also a safeguard against theft of the invention. No one who gets the idea from the inventor can successfully claim it as his own unless he can produce equally conclusive evidence antedating the disclosure to witnesses. Obviously it is important to select as witnesses persons who are trustworthy.

If the inventor desires further time to mature his invention, he may file a caveat in the Patent Office. This entitles him to notice if any other person within one year files year files an application for patent which would interfere; and he must then within three months prepare and file his own application, after which the Patent Office proceeds with the aid of testimony, or otherwise, to determine which applicant made the invention first. A caveat costs nearly as much as a formal application for patent, and lacks most of the advantages of the latter. It is usually better to file no caveat, but, instead, to have sketches and drawings of the invention witnessed as they develop, and to file the formal application promptly.

Reduction to Practice

The inventor should proceed with diligence to reduce his invention to practice, by putting a working specimen into use. An inventor who is the first to conceive an invention, but who is not diligent in reducing to practice, will be denied a patent in favor of a person who invents it later and reduces with diligence. The filing of an application for patent has been adjudged to have the same effect as a reduction to practice, and is, in fact, called a "constructive" reduction to practice. Hence the importance of filing

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