Page:The American Cyclopædia (1879) Volume XVI.djvu/615

 WHEEL 591 for Arithmetical Progression" (1854-'5), and "Automatic Telegraphy " (1859). Wheatstone was one of the jurors in the class for heat, light, and electricity in the Paris exposition of 1855. In 1868 he was knighted and received the Cop- ley medal of the royal society for his researches in acoustics, optics, electricity, and magnetism. WHEDON, Daniel Denison, an American clergy- man, born in Geddes, Onondaga co., N. Y., March 20, 1808. He graduated at Hamilton college in 1828, and studied law. He was pro- fessor of ancient languages and literature in the Wesleyan university, Middletown, Conn., from 1832 to 1843, and in 1836 was ordained as a minister of the Methodist Episcopal church. In 1845 he was elected professor of rhetoric, logic, and history in the university of Michi- gan, which post he filled for eight years ; and in 1856 he .was elected editor of the "Metho- dist Quarterly Review " and general editor of the publications of the Methodist book con- cern, New York, which post he still holds (1876). He has published " Public Addresses, Collegiate and Popular" (1856); "The Free- dom of the Will" (1864); and a "Commentary on the New Testament" (4 vols., 1866 et seq., to be completed with vol. v.). WHEEL, a solid piece or frame of wood or metal, usually circular, fixed to or movable upon a solid axis, about the centre line of which in either case it is intended to turn. The solid axis, when the wheel moves freely upon it, is commonly called an axle ; when the wheel is fixed to and turns with it, an arbor or shaft. The true or mathematical axis is al- ways the fixed line about which the revolution of the wheel occurs. This line, or a point in it, is also called the centre of the wheel. When, as is ordinarily the case, this centre of motion coincides with the centre of form, we have a centred wheel ; in case the centre of motion is to one side of the centre of form, an eccentric wheel. Both these sorts of wheels are circu- lar; but for peculiar purposes wheels which are elliptical, or of a variety of curved out- lines, are employed. Wagon wheels are usual- ly made of wood, with a band of iron. Water wheels are made of wood, supported by iron. Wheels for heavy machinery, whether to be connected with cogs or by bands, are usually made of iron, but sometimes of iron and wood, and sometimes of brass. Wheels for clocks and watches are usually made of brass, as they also are in philosophical apparatus. The vari- ous kinds of wheels are designated according to their uses ; as fly wheels, for equalizing the motion of machinery by employing the reserved force of the momentum of a rapidly rotating wheel ; balance wheels, such as are used in clocks and watches as parts of the escapement ; crown wheels, having the cogs or teeth upon the face ; spur wheels, having them upon the periphery ; band or belt wheels, which com- municate motion to each other by means of bands; ratchet wheels, which are held from moving in one direction by means of a ratchet, 834 VOL. xvi. 38 &c. When two wheels are placed upon a common axle, and one is much larger than the other, the former is called a wheel and the latter a pinion ; and the cogs of the pinion are technically called leaves. By a train of wheels, or of wheelwork, is usually meant more than two wheels through which motion is succes- sively transmitted. Evidently, the teeth upon two wheels or a wheel and pinion intended to engage, must be of like size and of correspond- ing form. The cutting and forming of the teeth, so as to secure continued rolling and action, with the least practicable jar, needless friction, and wear, is a consideration of much importance, and to which much study has been given. Two general forms have been found best to satisfy these conditions: 1, that in which the general outline of the teeth is that of epicycloids or hypocycloids ; 2, that in which they have the form of involutes of a circle. For the manner of determining these curves in practice for teeth of wheels having various sizes, and the use of the odontograph, by aid of which the curves are described, as well as for specific information respecting wheel work and the variety of other connec- tions in machinery which cannot here be de- tailed, the reader is referred to Willis's " Prin- ciples of Mechanism," Buchanan's "Practical Essays on Mill Work and other Machinery," Mosely's "Mechanical Principles of Engineer- ing," &c., Eankine's "Applied Mechanics," and other similar works. Carriage wheels, in order to bear without fracture the con- cussions to which they are subject, require to be exceedingly strong, and somewhat elas- tic. Ordinary carriage wheels consist of a cylindrical block at the middle, the nave, turning on an axle, and having spokes in the direction of radii, which unite the nave with the wooden circular segments or fellies con- stituting the rim, which are enclosed and held together by a wrought-iron tire. The- tire, being made slightly small for the rim, is. expanded by heating to redness, and in this, condition is driven upon the rim and bolted to- it; the contraction of the metal in cooling binds the fellies very firmly to one another and upon the spokes. Carriage or wagon wheels may be made flat ; but they are most commonly " dishing " from the nave outward to the rim, for the double purpose of securing width of base to the vehicle, so as to lessen the danger of overturning, and of enabling the wheel better to resist lateral shocks. M. A* Morin found, as the result of many experi- ments, the ratio of the resistance to be over- come by the team to the whole load, with various styles of heavy-loaded wagons, to vary from s> T on a wet road with ruts, to -fa on a solid, dry road of hard gravel ; the friction at the axles being, of course, reduced by the best lubricants. Generally, it may be stated that the ratio of draught to load on well macadam- ized roads in good order will be ^ to 5 V ! on fresh gravelled roads, often as great as -, 1, ; on.