Page:Popular Science Monthly Volume 49.djvu/748

724 Something must be said, however, of the sentence which Mr. Spencer has quoted in which, referring to his proposed plan for relating units of length to units of weight and capacity, Herschel says, "And thus the change which would place our system of linear measure on a perfectly faultless basis would at the same time rescue our weights and measures of capacity from their present utter confusion."

It is usually considered to be hardly fair to pick a single sentence out of a group and quote it as representing the views of another; and cutting a sentence in two in the middle, when the last half is against you, is a practice so generally condemned that we are compelled to believe that Mr. Spencer must have accidentally fallen into it in this instance. Indeed, if full quotation had been naade of what preceded this sentence and upon which it is founded, the one, rather meaningless, argument against us would have been changed to two very good points in our favor. Sir John suggested that the inch be increased by its one-thousandth part, so that it might be one five-hundred-millionth of the polar radius of the earth. He then undertook to show that by increasing the grain (by legislative enactment) by its one-eighteenth part, a cubic foot of water would weigh one thousand ounces, thus furnishing a decimal connection between the unit of weight and that of volume. This interesting scheme affords another illustration of the danger of patching up old and unsatisfactory systems, for a recent determination of the weight of a cubic inch of water by Mr. Chaney, in charge of the imperial standards in London, reveals the fact that the quantities on which Herschel based his calculations and suggestions were in error many times greater than was the metre, against which his arguments were directed. The complete sentence, of which Mr. Spencer quoted one half, as above, is as follows: "And thus the change which would place our system of linear measure on a perfectly faultless basis would at the same time rescue our weights and measures of capacity from their present utter confusion, and secure that other advantage, second only in importance to the former, of connecting them decimally with that system on a regular, intelligible, and easily remembered principle; and that by an alteration practically imperceptible in both cases, and interfering with no one of our usages or denominations." The words following "confusion" were omitted by Mr. Spencer, and they have been italicized to invite attention to their great significance as showing that the decimalisation of the new system of weights and measures was earnestly sought for by Herschel. That Mr. Spencer is violently opposed to this can only with great reluctance be accepted as a reason for the abrupt termination of his quotation.

Before beginning the exposition of his own views he ventures