“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 minds 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 force exerted to bring it to the earth: for instance, 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.” “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 objections.”