460 
PROFESSOR SCHUMACHER ON THE LATE 
“ The above value of the divisions of the balance was determined by means of six different weights 
“ of ’03 gr. each, and three of '02 gr. each, one pound being in each scale. 
Div. 
0-8 
5-5 
1-3 
5'6 
1-6 
5-6 
1-5 
5- 6 
1-8 
6 - 0 
1-4 
53 
Diff. 
4-7 
4-2 
4-3 
4-0 
4-0 
4-1 
4-1 
3- 8 
4'2 
4- 6 
3-9 
Div. 
1- 9 
4- 7 
2 - 1 
5- 0 
1-9 
4-1 
Diff. 
2-8 
2-6 
2-9 
31 
2-2 
Mean = 2*72 
§ — 1 '36 = ‘01 gr.” 
Mean 4T7 
X - i-39 = -01 gr. 
5. Captain Rater’s last result, by which he found K too heavy 0*0259 gr., agrees 
with that found by me, by Robinson’s pound, within 0*0036 gr., but differs from its 
first result 0*0299 gr. He seems inclined to explain it by an increase of weight in 
the mean time, and this was also my opinion when I sent the pound back to him. It 
had not then the brilliancy of polish which it had when it arrived ; and I thought 
oxydation might have increased the weight ; but when I had it back in the autumn 
of 1829, I compared it again with the weights inclosed in Robinson’s balance, with 
which it had been compared upon its arrival in 1827, and there was no sensible dif- 
ference from the first comparison It is therefore more probable that the first com- 
parison made by Captain Rater with his own weights, being only intended to see 
that Mr. Bate had not made any great error , were not made with that care with 
which he compared it afterwards in 1829. 
6. But before I got Captain Rater’s answer, (of May 31, 1829,) I considered that 
a copy from two copies would hardly answer my purpose, and that, to obtain the 
accuracy at which I aimed, I should have a copy from the original, and that that 
copy, in order to preserve its accuracy, must not be made of a metal liable to oxyda- 
tion, but of platina. I wanted at the same time more numerous comparisons than 1 
could with any propriety charge my English friends with ; and resolved to send one 
of my assistants (Captain Nehus, of the Royal Danish Engineers) to London, in 
order to make them. A platina pound was therefore ordered of Mr. Robinson. 
Our Government applied to the English Government to obtain for Captain Nehus 
* The brass weights of Robinson with which it was compared were of 5000 gr., 400 gr., 300 gr., (the rest 
were of platina,) and had a larger surface than Bate’s pound. It is possible that the three brass weights of 
Robinson may in the mean time also have increased in weight by oxydation ; but this increase ought to have 
been just equal to that of Bate’s pound, as the comparisons in 1827 and 1829 gave the same result. Now it 
is not very probable that Robinson’s weights should have been subjected to a smaller oxydation, and just in 
the inverse ratio of the surfaces smaller than Bate’s pound. It is more probable that both weights have not in 
those two years suffered from oxydation. 
