COMPARISON OF BAROMETERS. 
783 
with the brass covering of the bulb of E, and the corresponding readings of B and E 
observed. At this time the freezing-point of B was 0°'22 lower than in 1855. Tlie 
readings of a thermometer free from error are denoted by t. 
No. of comparisons. 
B. 
E. 
B-E. 
#-B. 
t - E . 
10 
5*25 
3-75 
-0-50 
+ 0-05 
-0-45 
10 
7-46 
7-94 
-0-48 
+ 0-03 
— 0-45 
17 
9-73 
10-12 
-0-39 
-0-01 
-0-40 
9 
11-65 
12-09 
-0-44 
-0-03 
-0-47 
9 
15-10 
15-52 
-0-42 
-0-03 
-0-45 
7 
21-58 
22-03 
-0-45 
-0-06 
-0-51 
Mean 
-0-45 
Since the reduction of F to 
0° C., ' 
with a temperature E 0°‘‘ 
45 too great, would 
make the reduced value 
of F 0'055 mm. too small, the error of E will be corrected 
by adding 0*45 mm. instead of 0‘39 mm. to the reduced value of F. 
Subsequently, by the kindness of the Rev. W. T. Kingsley, 
an opportunity was 
afforded of comparing F with a 
Standard barometer having a tube of very large bore. 
also constructed by Ernst, belonging to the Taylor Library in 
Sidney-Sussex Col- 
lege, Cambridge. According to the maker’s statement, the reading of this barometer 
is 0*04 mm. too great. 
Taylor. 
Att. therm. 
F. 
E. 
April 11, 1851. 
761-28 
9-50 
760-80 
10-00 
761-28 
9-60 
760-85 
10*10 
761-32 
9-75 
760-90 
10-20 
761-22 
9-75 
760-87 
10-15 
761-18 
9-75 
760-80 
10-30 
761-26 
9-69 
760-84 
10-15 
April 12. 
760-78 
9-25 
760-38 
9-6 
760-80 
760-42 
760-83 
9-5 
760-40 
9-8 
760-74 
9-6 
760-30 
10-1 
760-74 
760-36 
760-74 
9-75 
760-30 " 
10-2 
760-76 
9-52 
760-36 
9-92 
T. 
Att. therm. 
F. 
E. 
Means 
...761-01 
9-60 
760*60 
10-03 
Taylor— F=0'41 mm. But 
Taylor stands 0’04 
mm. too high. Therefore F is 
0‘37 mm. too low. E is 0°'43 higher than the attached thermometer of Taylor. The 
redaction due to 0°‘43 is 0 053 mm. Therefore the error of E will be corrected by 
adding 0 423 mm. instead of 0'37 mm. to the reduced height of F. 
The mean of the two corrections gives 0*44 millimetre to be added to the height of 
F reduced to 0° C. The reductions were made by the tables in Schumacher’s 
Jahrbuch fiir 1838. 
