724 POPULAR SCIENCE MONTHLY. 



Sometliing 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 sen- 

 tence out of a group and quote it as representing the views of 

 another ; and cutting a sentence in two in the middle, luhen 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 gr^ain 

 (by legislative enactment) by its one-eighteenth part, a cubic foot 

 of water would weigh one thousand ounces, thus furnishing a deci- 

 mal 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 deter- 

 mination 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 sen- 

 tence, of which Mr. Spencer quoted one half, as above, is as fol- 

 lows: "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 imijortance to the former, of connecting them decimally luith 

 that system on a regular, intelligible, and easily remembered prin- 

 ciple ; and that by an alteration practically imperceptible in both 

 cases, and interfering with no one of our usages or denomina- 

 tions." 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 ter- 

 mination of his quotation. 



Before beginning the exposition of his own views he ventures 



