198 M E T M E T Zinc-methyl is a colourless liquid of 1 386 specific gravity at 10 - 5, which boils at 46 C. ; in contact with air it takes fire. Water decomposes it at once into hydrate of oxide of zinc and marsh gas, Zn(CH 3 ) 2 = Zn(OH) 2 +2CH 3 H. Of other reactions the following may be named. (1) When digested with sodium, it yields a precipi tate of metallic zinc, and a double compound of itself and sodium- methyl. This latter unites readily with carbonic acid into acetate of soda, NaCH 3 + C0 2 = CH 3 CO ONa (Wanklyn). (2) With chloride of acetyl it forms acetone, Zn(CH 3 ) 2 + 2CH 3 . CO. Cl = ZnCl 2 + 2CO(CH 3 ) 2 (Freund). (3) Under somewhat different condi tions, including the presence of an excess of Zn(CH 3 ) 2 , a compound is produced which with water, yields tertiary butyl-alcohol (Boutle- row) : CO(CH 3 ) 2 + Zn(CH 3 ) = C(CH 3 ) 3 . . ZnCH 3 = A ; A + 2H . OH = Zn(OH) 2 + CH 4 + C(CH 3 ) 3 - OH . Tertiary alcohol. ( W. D. ) METRONOME, an instrument for denoting the speed at which a musical composition is to be performed. Its invention is generally, but falsely, ascribed to Johann Nepomuk Maelzel, a native of Ratisbon (1772-1838). It consists of a pendulum swung on a pivot ; below the pivot is a fixed weight, and above it is a sliding weight that regulates the velocity of the oscillations by the greater or less distance from the pivot to which it is adjusted. The silent metronome is impelled by the touch, and ceases to beat when this impulse dies ; it has a scale of numbers marked on the pendulum, and the upper part of the sliding weight is placed under that number which is to indicate the quickness of a stated note, as M.M. (Maelzel s Metronome) GI = 60, or = 72, or = 108, or the like. The number 60 implies a second of time for each single oscillation of the pendulum, numbers lower than this denoting slower, and higher numbers quicker beats. The scale at first ex tended from 50 to 160, but now ranges from 40 to 208. A more complicated metronome is impelled by clock-work, makes a ticking sound at each beat, and continues its action till the works run down ; a still more intricate machine has also a bell which is struck at the first of any number of beats willed by the person who regulates it, and so signifies the accent as well as the time. The earliest instrument of the kind, a weighted pendulum of variable length, is described in a paper by Etienne Loulie" (Paris, 1696; Amsterdam, 1698). Attempts were also made by Enbrayg (1732) and Gabory (1771). Harrison, who gained the prize awarded by the English Government for his chronometer, published a description of an instru ment for the purpose in 1775. Davaux (1784), Pelletier, Abel Burja (1790), and Weiske (also 1790) described their various experiments for measuring musical time. In 1813 Gottfried Weber, the composer, theorist, and essayist, proposed a weighted ribbon graduated by inches or smaller divisions, which might be held or otherwise fixed at any desired length, and would infallibly oscillate at the same speed so long as the impulse lasted ; this, the simplest, is also the surest, the most enduring, the most portable, and the cheapest invention that has come before the world, and one can but wonder that it has not been universally accepted. Stockel and Zmeskall produced each an instru ment ; and Maelzel made some slight modification of that by the former, about the end of 1812, which he announced as a new invention of his own, and exhibited from city to city on the Continent. It was, as nearly as can be ascertained, in 1812 that Winkel, a mechanician of Amsterdam, devised a plan for reducing the inconvenient length of all existing instruments, on the principle of the double pendulum, rock ing on both sides of a centre and balanced by a fixed and a variable weight. He spent three years in completing it, and it is described and commended in the Report of the Netherlands A cademy of Sciences, August 14,1815. Maelzel thereupon went to Amsterdam, saw Winkel and inspected his invention, and, recognizing its great superiority to what he called his own, offered to buy all right and title to it. Winkel refused, and so Maelzel constructed a copy of the instrument, to which he added nothing but the scale of numbers, took this copy to Paris, obtained a patent for it, and in 1816 established there, in his own name, a manu factory for metronomes. When the impostor revisited Amsterdam, the inventor instituted proceedings against him for his piracy, and the Academy of Sciences decided in Winkel s favour, declaring that the graduated scale was the only point in which the instrument of Maelzel differed from his. Maelzel s scale was needlessly and arbitrarily complicated, proceeding by twos from 40 to 60, by threes from 60 to 72, by fours from 72 to 120, by sixes from 120 to 144, and by eights from 144 to 208. Dr Crotch con structed a time-measurer, and Henry Smart (the violinist, and father of the composer of the same name) made another in 1821, both before that received as Maelzel s was known in England. In 1882 James Mitchell, a Scotsman, made an ingenious amplification of the Maelzel clock-work, reducing to mechanical demonstration what formerly rested wholly on the feeling of the performer. Although " Maelzel s metronome " has universal acceptance, the silent metronome and still more Weber s graduated ribbon are greatly to be preferred, for the clock-work of the other is liable to be out of order, and needs a nicety of regulation which is almost impossible ; for instance, when Sir George Smart had to mark the traditional times of the several pieces in the Dettingen Te Deum, he tested them by twelve metronomes, no two of which beat together. The value of the machine is exaggerated, for no living performer could execute a piece in unvaried time throughout, and no student could practise under the tyranny of its beat ; and conductors of music, nay, composers themselves, will give the same piece slightly slower or quicker on different occasions, according to the circumstances of performance. METSU, GABRIEL, a Dutch painter of celebrity (born in 1630, died after 1667), is one of the few artists of renown in Holland whose life has remained obscure. Houbraken, who eagerly collected anecdotes of painters in the 18th century, was unable to gather more from the gossip of his contemporaries than that, as early as 1658, Metsu, at the age of forty-three, submitted to a dangerous surgical operation. The inference drawn by superficial readers from this statement has been that death immediately ensued. A more careful perusal would have shown that Houbraken knew that Metsu had given lessons to De Musscher in 1665. Local records now reveal that Gabriel was the son of Jacques Metsu, who lived most of his days at Leyden, where he was three times married. The last of these marriages was celebrated in 1625, and Jacomma Garnijers, herself the widow of a painter, gave birth to Gabriel in 1630. Connected by both his parents with art, Metsu was probably taught first by his father and then by Gerard Dow. He probably finished his training under Rembrandt. So far back as 1648, but a few days earlier than Jan Steen, who is said to have painted his portrait, Metsu was registered in the painters corporation at Leyden; and the books of the guild also tell us that he remained a member in 1 649. In 1 650 he ceased to subscribe, and works bearing his name and the date of 1653 give countenance to the belief that he had then settled at Amsterdam, where he continued his studies under Rembrandt. His companions at the time would naturally be De Hooch and Van der Meer, whose example he soon followed when it came to his turn to select the class of subjects for which his genius fitted him. Under the influence of Rembrandt he pro duced the Woman Taken in Adultery, a large picture with the date of 1653, in the Louvre, in which no one would suspect the painter of high life or taverns were it not that his name is written at full length on the canvas. The
artist who thus repeated the gospel subjects familiar to