466 
PROFESSOR SCHUMACHER ON THE LATE 
totality of the determinations of the values of the parts of the graduated scale for re- 
ducing all the observations made with it. All these determinations were made with 
one troy pound in each scale. 
gr. pts. 
gr. pts, 
gr. pts. 
gr. pts. 
June 528. 
002 = 2 125 
July 5. 
0-02 = 1-800 
July 11. 
0-02 = 1-550 
July 14. 
002 = 1-550 
28. 
002 = 2050 
5. 
0-02 = 1-825 
11. 
0-02 = 1-650 
15. 
0-02 = 1-500 
29. 
0-02 = 1-975 
7. 
0-02 = 1-575 
12. 
0-02 = 1-800 
15. 
0-02 = 1-500 
29. 
0-02 = 1-850 
7. 
0-02 = 1-650 
12. 
0-02 = 1-700 
15. 
0-02 = 1-600 
July 1. 
0-02 = 1-575 
7. 
0-02 = 1-750 
12. 
0-02 = 1-750 
15. 
0-02 = 2-050 
1. 
0-02 = 1-450 
9. 
002 = 1-725 
12. 
0-02 = 1-650 
16. 
002 = 1-700 
4. 
0-02 = 1-800 
9. 
0-02 = 1-725 
12. 
0-02 = 1-700 
16. 
002 = 1-500 
4. 
0-02 = 1-935 
9. 
0-02 = 1-650 
14. 
0-02 = 1-650 
16. 
0-02 = 1-600 
4. 
0-02 - 1-675 
9. 
0-02 = 1-775 
14. 
0-02 = 1-650 
16. 
002 = 1-900 
5. 
0-02 = 1-575 
9. 
0-02 = 1-750 
14. 
0-02 = 1-500 
Mean from June 28 to July 16 0 - 78 gr. = 66'735 parts, or 1 part 
= 0-01169 gr. 
July 30. 
0 02 = 2-100 
August 2. 
0-02 = 1-875 
August 4. 
0-02 = 1-875 
August 6. 
0-02 = 1-900 
August 1. 
0-02 = 2-025 
2. 
0-02 = 1-950 
4. 
0-02 = 1-825 
6. 
0-02 = 1-925 
1. 
0-02 = 2-000 
2. 
0-02 = 1-950 
5. 
0-02 = 1-950 
2. 
0-02 = 1-875 
3. 
0-02 = 2-075 
5. 
0-02 = 1-875 
Mean from July 30 to August 6 0-28 
gr. = 27-200 parts, or 1 part 
= 0-01029 gr. 
Between the 16th of July and the 30th of that month there is a fortnight in which 
the balance has not been employed. As this interval may have affected the sensi- 
bility of the balance, it seems preferable not to take a mean of all the observations, 
but to divide them into two groups; one from June 28 to July 16, the other from 
July 30 to August 6. Indeed it appears, by inspection, that to 0‘02 gr. in the last 
period belong more parts than in the former. We shall consequently employ the 
two values 
from June 28 to July 16, 1 part = 0’01 169 gr. 1 , , 
/• t i r* r\ a. a > Robinson s balance, 
from July 30 to Aug. 6, 1 part = 0 - 01029 gr. J 
10. The barometer used in the course of these comparisons was lent by Messrs. 
Troughton and Simms to Captain Nehus, because the instrument ordered before for 
that purpose was not finished when Captain Nehus arrived in England. He received 
it but some days before his return. Captain Nehus compared the instrument of 
Messrs. Troughton and Simms 19 times, from June 17 to June 27, with the barome- 
ter of the Royal Society, and found that 0‘066 inch must be added to its indications 
in order to correspond with those of the instrument of the Royal Society. 
This instrument, after the experiments were completed, was returned to the owners, 
and could of course not be immediately compared with my standard barometer of 
Buzengeiger, whose tube has an interior diameter of nearly 8 French lines. It was, 
however, compared with my standard by means of a mountain barometer of Dol- 
lond, which Captain Nehus brought over, and which had in London been compared 
with the instrument of Messrs. Troughton and Simms. According to these compari- 
sons 0’057 inch must be added to its indications to reduce them to absolute heights. 
I have adopted this correction, which differs 0'009 inch from that given by the baro- 
meter of the Royal Society, because my standard is furnished with an apparatus 
serving to verify the position of the microscope with regard to the divided scale, and 
