Page:EB1911 - Volume 18.djvu/938

 MOTHERWELL, WILLIAM (1797–1835), Scottish poet, antiquary and journalist, was born at Glasgow on the 13th of October 1797, the son of an ironmonger. At the age of fifteen he was apprenticed in the office of the sheriff-clerk at Paisley, and appointed sheriff-clerk depute there in 1819. He spent his leisure in collecting materials for a volume of local ballads which he published in 1819 under the title of The Harp of Renfrewshire. In 1827 he published a further instalment in Minstrelsy Ancient and Modern, prefaced by an excellent historical introduction. He contributed verses to newspapers and magazines, Jeanie Morrison, My Heid is like to rend, Willie, and Wearie’s Cauld Well being his best-known poems. He became editor of the Paisley Advertiser in 1828, and of the Glasgow Courier in 1830.

A small volume of his poems was published in 1832, and a larger volume with a memoir in 1846, reissued, with additions, in 1848.

MOTHERWELL, a municipal and police burgh of Lanarkshire, Scotland. Pop. (1851), 900; (1901), 30,418. It is situated near the right bank of the Clyde, 13 m. S.E. of Glasgow by the Caledonian railway. It takes its name from an old well dedicated to the Virgin, and owes its rapid increase to the coal and iron mines in the neighbourhood. It has large iron and steel works, bridge-building being a distinctive industry. Boilers, steam-cranes and ironmongers’ ware are also made, and there are brick, tile and fireclay works. The public buildings include the town-hall, theatre and hospital; the park was presented in commemoration of Queen Victoria’s Jubilee. MOTION (Lat. motio, from movere, to move), in English law, an application made to a court during the progress of an action, and either before or after judgment has been pronounced. The object of a motion is to invoke the assistance of the court in matters that are of a pressing character, and require to be speedily dealt with. A motion differs from a petition in that it is made viva voce in open court and is founded on a written statement. Motions are either motions of course or special motions. A motion of course is made ex parte without notice, and is not mentioned in court, the party being entitled as of right. Motions of course are confined to the chancery division of the High Court. A special motion is made in open court, and must be supported by proper evidence. Special motions are made either ex parte or on notice. On all ex parte applications the utmost good faith must be observed. Ex parte motions, in the king’s bench division, are usually made to a divisional court. A motion for judgment is a proceeding whereby a party to an action moves for judgment of the court in his favour. See Rules of the Supreme Court, Ors. xl., lii.

MOTION, LAWS OF. Before the time of Galileo (1564–1642) hardly any attention had been paid to a scientific study of the motions of terrestrial bodies. With regard to celestial bodies, however, the case was different. The regularity of their diurnal revolutions could not escape notice, and a good deal was known 2000 years ago about the motions of the sun and moon and planets among the stars. For the statement of the motions of these bodies uniform motion in a circle was employed as a fundamental type, combinations of motions of this type being constructed to fit the observations. This procedure&mdash;which was first employed by the great Greek astronomer Hipparchus (2nd century ), and developed by Ptolemy three centuries later—did not afford any law connecting the motions of different bodies. Copernicus (1473–1543) employed the same system, and greatly simplified the application of it, especially by regarding the earth as rotating and the sun as the centre of the solar system. Kepler (1571–1630) was led by his study of the planetary motions to reject this method of statement as inadequate, and it is in fact incapable of giving a complete representation of the motions in question. In 1609 and 1619 Kepler published his new laws of planetary motion, which were subsequently shown by Newton to agree with the results obtained by experiment for the motion of terrestrial bodies.

The earliest recorded systematic experiments as to the motion of falling bodies were made by Galileo at Pisa in the latter years of the 16th century. Bodies of different substances were employed, and slight differences in their behaviour accounted for by the resistance of the air. The result obtained was that any body allowed to fall from rest would, in a

vacuum, move relatively to the earth with constant acceleration; that is to say, would move in a straight line, in such a manner that its velocity would increase by equal amounts in any two equal times. This result is very nearly correct, the deviations being so small as to be almost beyond the reach of direct measurement. It has since been discovered, however, that the magnitude of the acceleration in question is not exactly the same at different places on the earth, the range of variation amounting to about %. Galileo proceeded to measure the motion of a body on a smooth, fixed, inclined plane, and found that the law of constant acceleration along the line of slope of the plane still held, the acceleration decreasing in magnitude as the angle of inclination was reduced; and he inferred that a body, moving on a smooth horizontal plane, would move with uniform velocity in a straight line if the resistance of the air, and friction due to contact with the plane, could be eliminated. He went on to deal with the case of projectiles, and was led to the conclusion that the motion in this case could be regarded as the result of superposing a horizontal motion with uniform velocity and a vertical motion with constant acceleration, the latter identical with that of a merely falling body; the inference being that the path of a projectile would be a parabola except for deviations attributed to contact with the air, and that in a vacuum this path would be accurately followed. The method of superposition of two motions may be illustrated by such examples as that of a body dropped from the mast of a ship moving at uniform speed. In this case it is found that the body falls relatively to the ship as if the latter were at rest, and alights at the foot of the mast, having consequently pursued a parabolic path relatively to the earth.

The importance of these results, limited though their scope was, can hardly be overrated. They had practically the effect of suggesting an entirely new View of the subject, namely, that a body uninfluenced by other matter might be expected to move, relatively to some base or other, with uniform velocity in a straight line; and that, when it does not move in this way, its acceleration is the feature of its motion which the surrounding conditions determine. The acceleration of a falling body is naturally attributed to the presence of the earth; and, though the body approaches the earth in the course of its fall, it is easily recognized that the conditions under which it moves are only very slightly affected by this approach. Moreover, Galileo recognized, to some extent at any rate, the principle of simple superposition of velocities and accelerations due to different sets of circumstances, when these are combined (see ). The results thus obtained apply to the motion of a small body, the rotation of which is disregarded. When this case has been sufficiently studied, the motion of any system can be dealt with by regarding it as built up of small portions. Such portions, small enough for the position and motion of each to be sufficiently specified by those of a point, are called “particles.”

Descartes helped to generalize and establish the notion of the fundamental character of uniform motion in a straight line, but otherwise his speculations did not point in the direction of sound progress in dynamics; and the next substantial advance that was made in the principles of the subject was due to Huygens (1629–1695). He attained correct views as to the character of centrifugal force in connexion with Galileo’s theory; and, when the fact of the variation of gravity (Galileo’s acceleration) in different latitudes first became known from the results of pendulum experiments, he at. once perceived the possibility of connecting such a variation with the fact of the earth’s diurnal rotation relatively to the stars. He made experiments, simultaneously with Wallis and Wren, on the collision of hard spherical bodies, and his statement of the results (1669) included a clear enunciation of the conservation of linear momentum, as demonstrated for these cases of collision, and apparently correct in certain other cases, mass being estimated by weight. But Huygens’s most important contribution to the