endless succession of them insures a wide diffusion of advantages. At the expiration of each patent, even if it has not been supplanted by a later and more valuable one, the public gets the benefit of the full economy it insures, and wherever an unexpired patent is supplanted by a new one, the public gets this benefit much earlier. Cost of production tends rapidly downward, and the public is the permanent beneficiary. _Patents as a Means of Curtailing Monopolies._--While a patent may sometimes sustain a powerful monopoly it may also afford the best means of breaking one up. Often have small producers, by the use of patented machinery, trenched steadily on the business of great combinations, till they themselves became great producers, secure in the possession of a large field and abundant profit. Moreover, in the case of a patent which builds up a monopoly and continues for the full seventeen years of its duration unsupplanted by any rival device, the public is likely to get more benefit than the patentee, or even the company which uses his invention. In widening the market for its product the company must constantly cater to new circles of marginal consumers, and must give to all but the marginal ones an increasing benefit that is in excess of what it costs them. Probably few patents have been issued in America which illustrate the unfavorable features of the system more completely than did the Bell telephone patent, which gave to a single company during a long period a monopoly of the telephone business; and yet there are few men of affairs who do not perceive that, in the saving of time which the telephone effected and in the acceleration of business which it caused, they gained from the outset more than they lost in the shape of high fees. Something of the same kind is true of the users of domestic telephones; for though they may cost more than they should, they do their share toward placing those who use them on a higher level of comfort.