Becher contends for Galileo, and states that one Trifler made the first pendulum clock at Florence, under the direction of Galileo Galilei, and that a model of it was sent to Holland. The Accademia del Cimento also expressly declared, that the application of the pendulum to the movement of a clock, was first proposed by Galileo, and put in practice by his son, Vincenzo Galileo, in 1649. Huygens, however, contests the priority, and made a pendulum clock before 1658; and he insists, that if ever Galileo had entertained such an idea, he never brought it to perfection. Beckmann says the first pendulum clock made in England, was constructed in the year 1662, by one Tromantil, a Dutchman; but Grignon affirms that the first pendulum clock was made in England, by Robert Harris, in 1641, and erected in Inigo Jones's church of St. Paul, Covent-garden.
Why does the pendulum move faster in proportion as its journey is longer?
Because, in proportion as the arc described is more extended, the steeper are its beginning and ending; and the more rapidly, therefore, the pendulum falls down at first, sweeps along the intermediate space, and stops at last.—Arnott.
Why is it extremely difficult to ascertain the exact length of the pendulum?
Because of the various expansion of metals, respecting which no two pyrometers agree; the changeable nature of the atmosphere; the uncertainty as to the true level of the sea; the extreme difficulty of measuring accurately the distance between the point of suspension and the centre of oscillation, and even of finding that centre; also the variety of terrestrial attraction, from which cause the motions of the pendulum are also liable to variation, even in the same latitude. In pursuing his researches, Capt. Kater discovered that the motions of the pendulum are affected by the nature of the strata over which it vibrates.
Why is the iron rim of a coach wheel heated before putting on?
Because the expansion of the metal occasioned by the heat, facilitates the operation of putting on the iron, while the contraction which follows, brings the joints of the wooden part together; and thus, binding the whole, gives great strength to the wheel.
Why does a bottle of fresh water, corked and let down 30 or 40 feet into the sea, often come up again with the water saltish, although the cork be still in its place?
Because the cork, when far down, is so squeezed as to allow the water to pass in or out by its sides, but on rising, it resumes its former size.
Why do bubbles rise on a cup of tea when a lump of sugar is dropped into it?
Because the sugar is porous, and the air which filled its pores then escapes to the surface of the tea, and the liquid takes its place.
Why is there an opening in the centre of the upper stone of a corn mill?
Because through this opening the grain is admitted and kept turning round between the stones, and is always tending and travelling outwards, until it escapes as flour from the circumference.
Why does water remain in a vessel which is placed in a sling and made to describe a circle?
Because the water, by its inertia of straightness, or centrifugal (or centre-flying) force, tends more away from the centre of motion towards the bottom of the vessel, than towards the earth by gravity.
Why does a young quadruped walk much sooner than a child?
Because a body is tottering in proportion to its great altitude and narrow base. Now, the child has this latter, and learns to walk but slowly, because of the difficulty, perhaps in ten or twelve months, while the young of quadrupeds, having a broad supporting base, are able to stand, and even to move about almost immediately; but it is the noble prerogative of man to be able to support his towering figure with great firmness, on a very narrow base, and under constant change of attitude.—Arnott.
THE ROYAL ACADEMY.
(From a Correspondent.)
The exhibition of works of art in the Royal Academy this year is equal to any preceding, except in the department of portraiture; nor is this deficiency by any means extraordinary, when we consider the severe loss the arts have sustained by the death of Sir Thomas Lawrence. We much regret that, out of one thousand two hundred and thirty-four productions, we can only enumerate a very small number for want of space:
No. 11. Dutch Coast—very fine and transparent in the colouring; painted by A. W. Callcott, R. A.
16. A Subject from the Winter's Tale—good. W. H. Worthington.
55. Progress of Civilization—painted for the Mechanics' Institute at Hull. This work is admirably conceived, and reflects great credit on the talents of Mr. H. P. Briggs.
56. Mary Queen of Scots meeting the Earl of Bothwell between Stirling and Edinburgh. Mr. Cooper has treated this subject with his usual care, and appears to have delineated the costume very accurately. The horses are spirited, and finely executed.
62. Portrait of Lady Lyndhurst—painted very much in the manner of Rembrandt, by D. Wilkie, R. A.
65 and 66. Portraits of their Majesties—painted for the Corporation of the Trinity House, by Sir William Beechy.
78. An Italian Family, by C. L. Eastlake, is an interesting picture, and extremely rich in colour.
79. The Maid of Judith waiting outside the tent of Holofernes, till her Mistress had consummated the deed that delivered her country from its invaders: a wonderful production, by Etty.
84. Scene near Hastings. Rev. T. J. Judkin.
86. Interior of a Highlander's House—very fine. Edwin Landseer.
105. Portrait of Miss Eliza Cooper—a chaste and highly-finished production, by Sir M. A. Shee.
Messrs. Pickersgill, Turner, Reinagle, Hilton, Newton, Constable, Good, Daniell, Clint, Kidd, Howard, Phillips, and Elford, have also some excellent pictures in the exhibition.