A shout of delight, from the whole juvenile party, announced the satisfaction which they felt at the success of their first experiment in Natural Philosophy.
Louisa observed, that she could not distinguish any interval between the actual contact of the stone with the water and the sound which it produced.
“At so small a distance as two hundred and fifty-six feet,” said her father, “the interval could not have exceeded in duration the fourth part of a second, and was, consequently, imperceptible: we might therefore, in the present instance, have accepted the sound as a signal of the stone’s arrival at the water, without prejudice to the result of the experiment.”
Mr. Seymour told his son, that the method which he had pursued was unobjectionable when the experiment did not extend beyond a few seconds: but that, if a case occurred in which a greater space of time were consumed, he would find his plan tedious: “Now,” continued he, “I will give you a general rule that will enable you to obtain the answer in a shorter time without the details of addition. ‘The spaces described by a falling body increase as the squares of the times increase.’ I conclude that you already know that the square of a number is the sum obtained by multiplying the number into itself.”
“Certainly,” answered Tom; “the square of 4 is 16; that of 3, 9, and so on.”
“This, then, being the case, you have only to square the number of seconds, and then multiply that product by 16, being the space described by the falling body in the first second, and you will have the required answer: apply this rule to the present case; the stone fell to the bottom in four seconds; square this number, 4×4=16; multiply this by 16, and we obtain 256.”
“That,” said Tom, “is certainly much more simple than my method.”
“And it has the advantage,” continued Mr. Seymour, “of being more portable for the memory.”
“Should any of the villagers observe us,” said Mrs. Seymour, “they will take us for a party of fortune-tellers.”
“Of fortune-tellers!” repeated Louisa, with surprise.