The patents now existing on lateral adjusting bearings have caused many attempts at other methods of taking up the wear. The validity of these patents is questioned by many, and considerable litigation has been the result, though in many cases makers prefer to use other devices to running the chance of a law suit. The happy medium adopted by others is to pay the royalty demanded; this is, perhaps, the best course to pursue if the said royalty is not made burdensome. Every maker, however, should assure himself, by special examination, if his particular bearing really infringes any patent before paying; the fact of it being a ball-bearing with a lateral adjustment is not an incontrovertible reason that it should infringe, since both of these elements are, in themselves, old. It is only a special ball-bearing with a special adjustment that is patented. Unhappily, however, the special adjustment is a screw. How the patent will stand, time alone can tell; its validity is certainly questionable. A word here in regard to paying royalties in general. Makers are too scrupulously averse to such payments, even when small, and buyers have the idea that any one who pays a royalty is naturally working at a disadvantage. This is not necessarily the case. Some would save more by the use of an ingenious machine for making the parts than several times the royalty often amounts to. In the manufacturing business there are so many ways of saving and losing money, that unless a careful watch is kept all round the little matter of royalty on some one part will fall into insignificance as compared with other leaks. The advertisement of a maker that he pays no royalty gives us but little assurance that he can make a better machine for less money. When a patent is evaded by slight changes, such, for instance, as the increase or decrease of an inch in the diameter of a wheel, it shows not so much a great shrewdness on the part of the pirate as a frailty in the patent; this sort of evasion of royalties is considered to be perfectly legitimate, however, and means that either the attorney who took out the patent was incompetent, or that there was but little invention to be claimed. ROLLERS. Theoretically there is less friction in roller- than in ball-bearings, as there need be no sliding action whatever in the former if well made. But in actual practice no bearing can be made in which there is no tendency of the rollers to run together; and if we place them in a frame to hold them apart we shall have about as much friction as when they rub against one another. The most perfect plan is to place a small roller between each of the larger; with this arrangement the friction is practically nothing. The action of rollers upon the boxes is always a pure rolling friction, which cannot be the case with balls after the slightest groove is worn in the casing.