802 PROF. W. H. MILLER ON THE CONSTRUCTION OF THE NEW STANDARD POUND. 
has returned it, though I cannot find it amongst rny papers. Even if you had 
Nehus’s original drawing you would not be able to find the volume, the only height 
he has measured being that of the whole pound. The heights of the points a, b, c are 
only found by holding a scale in a vertical position near the pound. The diameters 
on the contrary are measured.” 
By a comparison of the figure of U with a profile of V traced mechanically, and 
with careful measurements of its axis and diameters, the axis and the extreme 
diameters of the knob and cylindrical portion of U appear to be a very little 
greater than the corresponding dimensions of V, the differences in other parts being 
exactly where we might expect the drawing to be inaccurate from the manner in 
which it was made. (In the figures of the weights V, O, M, B, the dotted line is 
the profile of U.) The diameters and axis of U being measured with a bow-legged 
compass, were more likely to err in excess than in defect. Making every allowance 
for this, it did not seem possible, on looking at the profiles of U and V, to suppose 
that the volume of U was less than that of V. But the volume of O, as well as that 
of M, being less than that of V, it appeared that of the three weights V, O, M, 
V approximated most nearly to U in volume. As the existing data were utterly 
insufficient to determine how much, if at all, U exceeded V in volume, it appeared 
safest to assume the volumes of U and V to have been equal. This course was 
recommended also by Professor Schumacher in his letter of October 3, 1843. 
Long after this resolution had been taken and acted upon, and the new standard 
constructed in accordance therewith, the troy pound O came by purchase into the hands 
of the Committee. The surface of O was studded with numerous small pores, show- 
ing it to be an extremely bad casting. It was only after repeatedly boiling the water 
in which it was suspended that the air-bubbles which attached themselves to the pores 
ceased to appear. It was weighed in water April 2, and then left to dry till April 28, 
when on being weighed in air it appeared to be about 16 grains too heavy. By heat- 
ing it to above the boiling-point, the water that had been retained in the cavities was 
expelled, and the weight reduced to 5759‘83 grains. Afterwards, by placing it in a 
jar containing water, under the receiver of an air-pump, and alternately exhausting 
the receiver and boiling the water, the cavities communicating with the surface were 
found capable of containing 21 ’37 grains of water. This explains the seeming para- 
dox, that although the linear dimensions of O are hardly less than those of V, and 
sensibly greater than those of M and B, its specific gravity is considerably greater 
than that of V, and slightly exceeds that of either M or B. 
Of the weights used in the following weighings, those marked (100), (200), (400) ..., 
of nearly 100, 200, 400 ... grains respectively, are of bronze, for which log A=0'92260. 
The smaller weights are of platinum. By a mean of four observations, April 30, 1853, 
0^(3200)-l-(1600)-|-(800)-f-(100)-l-(32) + (16)-f (8)-l-(4) — 0T360 grain in air 
(D=12, C=12-2, F=756-4, E=ll-8). 
0 : 2 : 5699’9704 grains of bronze -f 59 8607 grains of platinum in air (^=12‘1, 
/; = 7b5’4). 
