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XXII. A Comparison of the late Imperial Standard Troy Pound weight with a Platina 
copy of the same, and with other standards of authority. Communicated hy Pro- 
fessor Schumacher, For. Memb. R.S., in a Letter to F. Baily, Esq., V.P. and 
Treas. R.S. 
Received June 9, — Read June 16, 1836. 
1. IS RING desirous of obtaining- an accurate copy of the English Imperial Standard 
Troy Pound, for an intended comparison of our weights therewith, I applied to the 
late Captain Kater, and he had the goodness to procure for me not only a copy 
made by Mr. Bate, exactly similar to those described in his paper*, but also a 
balance of Mr. Robinson, of the same dimension and construction as that used by 
himself in comparing the legal standard in the custody of the Clerk of the House of 
Commons. The copy of the Troy pound is of the same kind of brass as that used by 
Mr. Bate for the other copies sent by Captain Kater to different towns in Great 
Britain. It bears the stamp “T? P d 1824” ; the same stamp, in fact, that was upon 
the pound No. 2.'f~ which Captain Kater sent to Edinburgh. I shall designate this 
pound by the letter K. I received it, March 12, 1827, from the late Dr. Young. He 
had noted upon the cover of the box, “ Imperial Troy pound : found by Captain 
££ Kater to exceed the standard a very little, not more than '006 grain.” 
2. Fearing that this comparison (giving only one limit, for it is not said how much 
the difference is below 0'006 gr.) might not be made with that care which I thought 
necessary for the use I intended to make of the copy, I wrote again to Captain Kater, 
begging him to send me a second copy compared more carefully with the standard. 
He kindly undertook the task, ordered for me at Mr. Robinson’s a second copy made 
of brass, together with divisions by halves, and sent it me in the summer of 1 828, 
with the following notice : 
“ York Gate, Regent’s Park, 18th July, 1828. 
“ I carefully compared the Troy pound which Robinson made for you with two separate 
“ pounds of my own, the errors of which I had well determined. These pounds I designate the old 
“ pound and the unmarked pound. I will copy for your satisfaction the comparisons at length. 
The old pound is heavier than the imperial pound 
•0122 gr. = 1 • 83 div. (T5 div. being = ‘01 gr.) 
Prof. S.’s pound too heavy 0‘36 div. = 0 - 0024 gr. 
* Philosophical Transactions, 1826. t Ibid., p. 12. 
3 n 
Date. 
Old Pound. 
Prof. S.’s Pound. 
1828. 
June 10. 
4-5 
3T 
5-0 
3-9 
5-7 
3-8 
June 11. 
4-5 
3-0 
Mean . . . 
4-92 
3-45 
Deduct. . 
1-83 
3-09 
3-09 
0-36 
MDCCCXXXVI. 
