PROFESSOR SCHUMACHER ON THE LATE 
34. We may now put, in one view, the results thus obtained, using only four deci- 
mals, which is enough for the accuracy, of which the operation of weighing is capable. 
I have only used five decimals in the reductions, in order to have the fourth decimal 
not affected by the calculation. 
The reductions in § 33. give for the absolute weight of the five several pounds, 
compared with U, the following values, expressed in grains troy : the first when we 
suppose U of brass with the specific gravity = 8*0, the second when we suppose U 
of copper with the specific gravity == 8*788. 
U of Brass. 
Absolute weight of K = 5760-0346 
Absolute weight of S. p = 5759*4507 
Absolute weight of S. b = 5759*9654 
Absolute weight of RS = 5759*4558 
Absolute weight of RM = 5760*0095 
U of Copper. 
= 5760*1124 
= 5759*5287 
= 5760*0441 
= 5759*5340 
= 5760*0873 
If now the lost imperial standard troy pound should be restored by these five 
pounds, it must be made, 
if U was of Brass, 
0*0346 gr. lighter than K 
0*5493 heavier than S. p 
0*0346 heavier than S. b 
0*5442 heavier than RS 
0*0095 lighter than RM 
if U was of Copper, 
0*1124 gr. lighter than K 
0*4713 heavier than S. p 
0*0441 lighter than S. b 
0*4660 heavier than RS 
0*0873 lighter than M. 
The uncertainty of course that remains about the absolute weight of the lost 
standard is, by comparison with 
My brass pound, made by Bate, . . . 
My platina pound, 
My brass pound, made by Robinson, . 
The Royal Society’s platina pound, . . 
The Royal Mint brass pound, 
denoted by K = 0*0778 
denoted by S. p = 0*0780 
denoted by S. b = 0*0787 
denoted by RS = 0*0782 
denoted by RM = 0*0778 
or nearly 0*08 grain by all of them. 
35. Nor is this uncertainty brought within much smaller limits if we adhere to the 
most probable hypothesis, and suppose U of brass. The specific gravity of brass being 
a compound metal, varies very much according to its composition. I have known 
brass to vary from 7’9 to nearly 8*5 specific gravity*. In the same manner as before 
we may find the absolute weight of S. p , if we assume seven different specific gravities 
for U from 7*9 to 8*5, proceeding by 0*1. 
* I have recently met with a piece of cast brass (intended for a pendulum bar) the specific gravity of which 
is less than 7*4. — F. Baily. 
