, 
Ft 
Sept. 4, 1873] 
The test bar of this alloy, when loaded at the centre with 
54 cwt., broke without bending. 
4. The form of the standard to bea solid bar 38 in. 
long, and 1 in. square in section. The measure of a yard 
to be defined by the distance between two fine lines 
perpendicular to the axis of the bar, narked upon gold 
studs at the bottom of cylindrical holes drilled from the 
upper surface to the mid-depth of the bar. 
The gun-metal, or bronze, thus adopted for the new 
standard, has since been known as “ Baily’s metal,” and 
this designation is engraved upon the Imperial standard 
ard. 
‘4 In order to select the most perfect specimen for the 
new standard of length, 4o line-standard yards were con- 
structed of Baily’s metal, and one of these was finally 
selected as the Imperial standard, not only from its repre- 
senting, with the greatest precision, the assumed length 
of the lost standard yard, but also from the clearness of 
its defining lines, and from its general good workmanship. 
Four of the remaining yards nearest in length to the 
new standard were selected as Parliamentary copies, and 
deposited in the same places as the Parliamentary copies 
of the standard pound already mentioned; and the rest 
were in like manner distributed amongst different 
countries and public institutions in this country. 
Several other similar line-standard yards were also 
constructed for experimental purposes, being accurately 
verified by Mr. Sheepshanks, and were disposed of in like 
manner, viz. 
The defining terminations of these end-bars consist of 
a plug of agate, slightly conical and shrunk into a 
similar conical hole at each end of the middle axis of the 
bar. The ends of the bars are ground and polished 
in a spherical form, the centre of the spherical surface 
being the middle of the bar. 
All the numerous comparisons of the standard yards 
were made by Mr. Sheepshanks in one of the lower 
cellars at Somerset House, under the apartments of the 
Royal Astronomical Society, where the new micro- 
metrical comparing apparatus constructed for the 
purpose by Messrs. Troughton and Simms, was fixed. 
A full description of the comparing apparatus will be 
given under head V. of Weighing and Measuring 
Instruments, and their Use. 
The Commission for restoration of the standards having 
terminated their labours, recommended in their final re- 
port that the new imperial standards of the yard and 
pound be deposited at the Exchequer Office, there to be 
preserved under such reguiations as to Parliament might 
appear fitting. In expressing their adherence to the re- 
commendation of the Committee of 1841 that no reference 
should be made to natural elements for the values repre- 
sented by the standards of weight and measure, they also 
recommended that so much of the Act 5 Geo. IV.c. 74, as 
provided for the restoration of the standards in the man- 
ner therein provided be repealed, and that the standards 
should in no way be defined by reference to any natural 
basis, such as the length of a degree of the meridian on 
the earth’s surface in an assigned latitude, or the length 
of a pendulum vibrating seconds in a specified place. 
‘They considered the ascertaining of the earth’s dimen- 
sions and the length of the seconds pendulum in terms of 
the standard of length, and the determination of the 
weight of a certain volume of water in terms of the stan- 
dard of weight, as scientific problems of the highest im- 
portance, to the solution of which they trusted that Her 
Majesty’s Government would always give their most 
liberal assistance, but they did not urge them on the 
sae as connected with the conservation of stan- 
ards. 
These recommendations were carried into effect by the 
Act of 1855, 18 and 19 Vict. c. 72, for legalising and 
preserving the restored standards of length and weight, 
sec. I of which repealed the provisions of the Act of 1824 
NATURE 
369 
concerning the restoration of the standards by reference 
to the pendulum and to the weight of a cubic inch of 
water. 
Under the provisions of the Act of 1855, the imperial 
standards were deposited in 1855, in the office of the 
Exchequer. On the consolidation of the ancient Office 
of the Exchequer with the Audit Office in 1866, and the 
creation of the Standards Department of the Board of 
Trade, under the Standards Act, 1866, 29 and 30 Vict. 
c. 82, the custody of the imperial standards was trans- 
ferred to the Warden of the Standards, the head of the 
new Standards Department, and the imperial standards 
are now deposited in a fireproof iron chest in the strong 
room in the basement of the Standards Office, which has 
been specially adapted for their safe preservation. Pro- 
vision is contained in the Act for the comparison once in 
every ten years of the three Parliamentary copies of the 
imperial standards deposited at the Royal Mint, in charge 
of the Royal Society, and in the Royal Observatory, Green- 
wich, respectively, withthe imperial standards of length and 
weight, and with each other. Under this Act new scien- 
tific duties were also imposed upon the Standards Depart- 
ment, the Warden of the Standards being charged with 
conducting all such comparisons, verifications, and other 
operations with reference to standards of length, weight, 
or capacity, in aid of scientific researches or otherwise, 
as may be required. 
In connection with the question of the derivation of a 
standard unit of length from a natural constant to be 
found in the ascertained dimensions of the earth, it may 
be added that Sir John Herschel has pointed out the fact 
of the length of the polar axis having been determined, 
from the combined results of all the scientific measure- 
ments of arcs of the meridian, to be equal to 500,482,296 
inches of our imperial standard yard, and that if one 
five-hundred-millionth part of the polar axis were adopted 
as a new standard unit, to be called the “ geometrical 
inch,” it would differ from the imperial inch less than one- 
thousandth part of aninch ; a difference so small as not to 
be measured by any ordinary method, and only by the 
aid of the nicest scientific instruments. For all “ ordi- 
nary practical purposes,” the geometrical inch would be 
identical with the imperial inch ; whilst for high scientific 
measurements for astronomical purposes, it would connect 
by an unbroken numerical chain the small units with 
which mortals are conversant in their constructions and 
operations with the great features of nature, and more 
especially with those greater units in the measurements 
of the universe with which astronomy brings us in rela- 
tion. It would also produce a more exact ratio between 
our units of length and weight, the avoirdupois ounce 
being nearly a “ geometrical ounce,” or one-thousandth 
part of the weight of a geometrical cubic foot of distilled 
water. That is to say, whilst the existing legal weight of a 
cubic foot of distilled water is 997°136 ounces, the weight 
ofa geometrical cubic foot of water would be 998" ounces. 
And as the imperial half-pint is the measure of ten ounces 
of distilled water, the ratios of these units of length, 
weight, and capacity would thus be brought within such 
practical limits of precision as would meet every possible 
requirement of commercial exigency. 
Ill.—Derived Units and Multiples and Parts of Imperial 
Standard Units. 
THE IMPERIAL STANDARD GALLON AND BUSHEL. 
With respect to measures of capacity, the sole unit of 
all imperial measures of capacity, established by the 
Act of 1824 is the standard gallon, containing 10 lbs. 
avoirdupois of distilled water, weighed against brass 
weights in air at the temperature of 62° Fahr., the baro- 
meter being at 30 inches. From the imperial standard 
gallon is derived the imperial bushel of 8 gallons, the 
standard of capacity for dry goods commonly sold by 
heaped measure, or incapable of being striken. Various 
