It is evident that all this theory applied to one obstruction is simply repeated in a number of them, and a number of them make up a rough road, bearing in mind that a rut is but one form of an obstacle. Some makers of late seem to realize the importance of springs which will allow of a horizontal as well as a vertical motion, and have in them not only provided against the loss of momentum in the man, but also in the entire machine exclusive of the front wheel. This has apparently been done with another object in view,—_i.e._, that of relieving the annoyance to the hands and arms by reducing the vibration in the handle-bar. This object, though worthy, is far short of the ideal. Such springs might properly be called storage springs or power economizers; they are, however, generally nominated Anti-Vibrators and Spring Forks. CHAPTER X. ANTI-VIBRATORS AND SPRING FORKS. The abstract terms of the heading have, so far, generally been applied to certain devices constituting an elastic connection between the standards of the wheels (1), or, more precisely, between the front fork and backbone. The more recent forms of anti-vibrators are (2) the spring hinge about midway in the rear frame, or backbone, of the machine; (3) the spring joints at the extremity of the front fork connecting with the forward wheel axle; (4) the spring fork proper, in which the extensions are either wholly or in part elastic. The last two are, to my mind, the most deserving of praise. In the first named above, the shock is mainly confined to the front half of the machine,—that is, to the front wheel, its fork, and handle-bar,—while in the last two the front wheel alone receives the concussion to the full extent, an intervening spring preventing the transmission of the shock to other parts of the system. When it comes to be fully appreciated by the fraternity that the shock sustained by the machine and rider is not only to be treated as a matter of comfort or discomfort, but that it has other very important claims to our consideration, we may expect it to be more fully discussed. Not that we care so much about the vibration loosening every joint, screw, and pin in the entire contrivance, which makes it worn out, so called, when it has scarcely begun to wear,—of course, in the general march of progress, we expect to remedy that also,—but it is the momentum we are most after. The writer has always been one who has had a constitutional aversion to working up a speed and then having it all knocked out by a stray stone. [Illustration: Recent American anti-vibrator.]