The gains of the inventor cannot extend much beyond the period covered by his patent, unless some further and less legitimate monopoly arises. If the use of an important machine builds up a great corporation which afterward, by virtue of its size, is able to club off competitors that would like to enter its field, the public pays more than it should for what it gets; and yet even in these cases it almost never pays more than it gets. The benefit it derives is simply less cheap than it ought to be. Much of the power of the telephone monopoly has been extended beyond the duration of its most important patent, and that patent was in its day broader than it should have been; and yet there never was a time when the use of the telephone in facilitating business, and in saving time and trouble in a myriad of ways, did not far outweigh the total cost which the users of telephones incurred. As we shall soon see, important inventions invariably confer some benefit on the public at the start. The owner of the new device must find a market for his products, and must offer them on terms which will make it for the interest of the public to use them largely. _The Effect of Competition in Causing Improvements to Multiply._--Competition insures a large number of inventors and offers to each of them a large inducement to use his gifts and opportunities. A great corporation may employ salaried inventors and, because of its great capital and large income, it may experiment with inventions with far less risk to itself than an inventor usually takes. When large corporations compete actively with one another, the employment of salaried inventors is very profitable to them; and improvements in production go on more rapidly than they are likely to do after these firms consolidate with each other and cease to feel the spur which the danger of being distanced in a race affords. It is a fact of observation, and not merely an inference, that monopolies are not as enterprising as competing companies.