178 First Report of the Commissioners appointed to consider 



in this inquiry— we mean that of never giving an old name to a 

 new measure, except it differ ahiiost imperceptibly from the old 

 one that bears the same name, or except the new measure be a 

 medmm between several old ones of the same name which are to 

 be abandoned: for this variety of things with one name evidently 

 facilitates imposture. 



" Whatever be the means of capacity actually adopted, the ex- 

 pediency of having a new series of standards constructed, and 

 deposited at the Exchequer, and other appropriate offices, is 

 evident. But there is room for diversity of sentiment with re- 

 spect to the shape which shall be given to these standards. We 

 have every reason to believe that vessels in form of parallelopipeds 

 are most easily and accurately constructed. Yet we know that 

 where workmen are employed who are acquaijited with the most 

 correct processes for boring, hollow metallic cylinders may be 

 constructed with nearly equal accuracy." 



After a few scientific remarks on this subject, which we here 

 omit, the author proceeds thus : — 



" The standards of weight, as well as those of capacity, may 

 be drawn by an obvious process from that of length. It has been 

 ascertained by repeated experiments, from the time of Sir Jonas 

 Moore down tg the present, that a cubic foot of distilled water, 

 atlhe temperature of 564° on Fahrenheit's thermometer, and un- 

 ^^'" a*:! atmospheric pressure measured by 29'76 inches on the 

 '^^''.ometer, weighs precisely 1000 ounces avoirdupois. Conse- 

 "quently, a cubic tenth of a foot of the same liquid weighs an 

 ounce, a cube of two-tenths on each side a half-pound, and a 

 parallelopiped of the same base and double height (that is, four- 

 tenths) weighs a pound. Let, then, two cubes and a parallelo- 

 pided of the dimensions just specified be accurately formed of 

 brass or some other metal, and let each of them be carefully 

 weighed both in air and in water, of the above-mentioned tem- 

 perature, by means of a good hydrostatic balance ; the differences 

 of the weight in air and in water in the several cases will be pre- 

 cisely equal to the avoirdupois ounce, half pound, and pound re- 

 spectively. 



*' A standard of weight, suppose a pound, may also be found 

 by placing the parallelopiped before mentioned in a vessel, and 

 filling the vessel carefully with water at 55| deg. ; then removing 

 the parallelopiped, and weighing together the vessel and the wa- 

 ter it contains ; then filling the vessel again, and re-weighing it 

 with this additional portion of water ; the difference between the 

 two weights is manifestly the weight of 16-l,000dths of a foot of 

 water, and this, as before, is equivalent to a j)ound avoirdupois. 

 This process, however, is not so correct as the preceding, because 

 of the well-known difference which exists between the quantity 



. of 



