much delight; but the breakfast had been concluded, and yet Mr. Twaddleton was still

absent.

"What can have detained our worthy vicar?" exclaimed Mrs. Seymour; "he promised on Friday that he would pay us a very early visit this morning."

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"At present," observed Mr. Seymour, we can, fortunately, proceed without his assistance; for there yet remains a property of matter which must engage our attention."

"And what may that be?" asked Louisa. "ELASTICITY," replied her father; "and I wish to hear whether Tom can explain to us the meaning of the term."

Tom very well knew what was meant by Elasticity; but he was like many a merchant with a bill of exchange, who, although well acquainted with its value, has not sufficient small change to cash it. Tom wanted words to enable him to furnish a clear definition; his father, therefore, kindly relieved his embarrassment, by informing him that "it was a property inherent in certain bodies, by which they possessed a disposition to have their form altered by force or pressure, and to recover it on the re

moval of that pressure, throwing off the striking body with some degree of force; for example," continued he, "the cane, which I hold in my hand, can be bent to a certain extent, and then, if I let it go, it will immediately return to its former condition with considerable force."

Louisa enquired whether bending and press

Mr.

ing upon a body were the same thing. Seymour replied that the form of an elastic body might be altered either by compression, or distention, and that bending was, in fact, only a combination of these two methods: "for," said he, "when a straight body, like my cane, is bent, those particles of it which are on the one side are compressed, while those on the other are distended. But let us proceed with the subject. I have said that elastic bodies, on returning to their original form, throw off the striking body with some degree of force. I have here," continued Mr. Seymour, taking out of his pocket a wooden image of a cat, "a toy which I intend as a gift to John, it will serve to illustrate our subject. The tail you perceive is movable, one of its ends being tied to a piece of catgut, which is a highly elastic substance. When I bend the tail under the body of the

animal, I necessarily twist the string; and, by pressing the other end of the wooden tail upon a piece of wax, I can retain it for a few seconds in that situation."

Mr. Seymour having fixed the tail in the manner above described, placed the wooden image on the ground, when in a few seconds it suddenly sprang forward, to the great delight of the younger children.

"Can you explain this action ?" asked Mr. Seymour.

"The wax," answered Tom, "was incapable of holding the end of the tail longer than a few seconds; and as soon as it was let loose, the elasticity of the catgut enabled it to return to its former condition; in doing which, the tail struck with force against the ground, which threw off the body of the cat, and produced the leap."

"Very well explained; and you, no doubt, will readily perceive that the operation of steel springs depends upon the same principle of elasticity: a piece of wire or steel, coiled up, may be made to set a machine in motion, by the endeavour it makes to unbend itself. This is

our watches are what is termed down, this steel has uncoiled itself; and the operation of winding them up, is nothing more than that of bending it again for action. (6) If the elasticity of a body be perfect," added Mr. Seymour, "it will restore itself with a force equal to that with which it was compressed. As I have given John a toy, it is but fair that I should reward you, Tom: open that box, and examine the gift which it contains."

Tom received the present from his father, and proceeded to open the lid; when, to his great astonishment, the figure of an old witch suddenly sprang upwards. Mr. Seymour explained its mechanism, by stating "that the figure contained a wire coiled up, like a cork screw, and which, upon the removal of the pressure of the lid which confined it, immediately regained its original form.” (7)

Tom enquired what kind of bodies was most elastic. He was informed that the air was the most elastic of all known substances; and had, for that reason, been distinguished by the name of an elastic fluid. Hard bodies were so in the next degree; while soft substances which easily retain impressions, such as clay, wax, &c.,

might be considered as possessing but little elasticity.

"I should have thought," said Louisa, "that neither clay nor wax had possessed any elasticity."

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My love, we know not any bodies that are absolutely, or perfectly, either hard, soft, or elastic; since all partake of these properties, more or less, in some intermediate degree. Liquids are certainly the least elastic of all bodies; and, until lately, water was regarded as being perfectly inelastic: but recent experiments have shown it capable of compression, and of restoring itself to its original bulk, as soon as the pressure is removed; it must therefore possess some elasticity. Indeed," said Mr. Seymour, "we might have anticipated such a result, from the effects which present themselves in the well-known game of Ricochet,' or Duck and Drake."

"Duck and Drake !" exclaimed Louisa; "for goodness' sake, what can that game be?" "I dare say your brother will not have any difficulty in explaining it to you."

Tom informed her that it was a game in