strance, which was well understood by the whole party, he exclaimed

"You palter with us in a double sense,

That keeps the word of promise to the ear,
And breaks it to our hope.'

Tom begged that his father would explain to him how it could possibly be that the earth should not possess any weight.

"Weight, my dear boy, you will readily understand, can be nothing more than an effect arising out of the resisted attraction of a body for the earth: you have just stated, that all bodies have a tendency to fall, in consequence of the attraction of gravitation; but if they be supported, and prevented from approaching the earth, either by the hand, or any other appropriate means, their tendency will be felt, and is called weight."

Tom understood this explanation, and observed, that "since attraction was always in proportion to the quantity of matter, so, of course, a larger body must be more powerfully attracted, or be heavier, than a smaller one."

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Magnitude, or size, my dear, has nothing

* Macbeth.

whatever to do with quantity of matter: will not a small piece of lead weigh more than a large piece of sponge? In the one case, the particles of matter may be supposed to be packed in a smaller compass; in the other, there must exist a greater number of pores or interstices."

"I understand all you have said," observed Louisa," and yet I am unable to comprehend why the earth cannot be said to have any weight."

"Cannot you discover," answered Mr. Seymour, "that, since the earth has nothing to attract it, it cannot have any attraction to resist, and, consequently, cannot be correctly said to possess weight?"

The children declared themselves satisfied with this explanation, and Mr. Seymour proceeded to put another question: "since," continued he, " you now understand the nature of that force by which bodies fall to the earth, can you tell me the degree of velocity with which they fall ?"

Tom asserted, that the weight of the body, or its quantity of matter, and its distance from the surface of the earth, must, in every case,

determine that circumstance; but Mr. Seymour excited his surprise by saying, that it would not be influenced by either of those conditions; he informed them, for instance, that a cannon ball, and a marble, would fall through the same number of feet in a given time, and that, whether the experiment were tried from the top of a house, or from the summit of Saint Paul's, the same result would be obtained.

"I am quite sure," exclaimed Tom, "that, in the Conversations on Natural Philosophy, it is positively stated, that attraction is always in proportion to the quantity of matter.”

"Yes," observed Louisa," and it is moreover asserted, that the attraction diminishes as the distances increase."

Mr. Seymour said, that he perceived the error under which his children laboured, and that he would endeavour to remove it. "You cannot, my dears," continued he, "divest your mind of that erroneous but natural feeling, that a body necessarily falls to the ground without the exertion of any force; whereas the greater the quantity of matter, the greater must be the

stance, a substance which weighs a hundred pounds will thus require just ten times more force than one which only weighs ten pounds; and hence it must follow, that both will come to the ground at the same moment; for, although, in the one case, there is ten times more matter, there is, at the same time, ten times more attraction to overcome its resistance; for you have already admitted that the force of attraction is always in proportion to the quantity of matter: now let us only for an instant, for the sake merely of argument, suppose that attraction had been a force acting without any regard to quantity of matter, is it not evident that, in such a case, the body containing the largest quantity would be the slowest in falling to the earth ?"

"I understand you, papa," cried Tom; "if an empty waggon travelled four miles an hour, and were afterwards so loaded as to have its weight doubled, it could only travel at the rate of two miles in the same period, provided that in both cases the horses exerted the same strength."

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Exactly," said Mr. Seymour; " and to follow up your illustration, it is only necessary

to state, that Nature, like a considerate master, always apportions the number of horses to the burthen that is to be moved, so that her loads, whatever may be their weight, always travel at the same rate; or, to express the fact in philosophical instead of figurative language, gravitation, or the force of the earth's attraction, always increases as the quantity of matter, and, consequently, that heavy and light bodies, when dropped together from the same altitude, must come to the ground at the same instant of time."

Louisa had listened with great attention to this explanation; and although she thoroughly understood the argument, yet it appeared to her at variance with so many facts with which she was acquainted, that she could not give implicit credence to it.

"I think, papa," said the archly smiling girl, “I could overturn this fine argument by a very simple experiment.”

"Indeed! miss Sceptic: then pray proceed; and I think we shall find that the more strenuously you oppose it, the more powerful it will become: but let us hear your