US.] 
PORCELAIN AIR THERMOMETRY. 
Table 75. — Corresponding to Table 66. 
227 
Series V 
No. 
£20 
T 
No. 
e2o 
T 
No. 
620 
T 
microvolt. 
°ft 
microvolt. 
oft 
microvolt. 
°ft 
38 
5370 
512 
38 
9030' 
774 
38 
7580 
671 
38 
5560 
526 
38 
11700 
958 
38 
6860 
622 
38 
5900 
565 
38 
11950 
978 
38 
6300 
579 
38 
5930 
568 
38 
12300 
1002 
38 
5740 
539 
38 
6030 
560 
38 
12430 
1006 
38 
5290 
501 
38 
6100 
567 
38 
11470 
935 
38 
4880 
467 
38 
8340 
734 
38 
10130 
852 
38 
4450 
436 
38 
8500 
742 
38 
9190 
790 
38 
4100 
405 
38 
8850 
760 
38 
8270 
722 
raphio digests. — The results of these four tables may be platted 
iphically by making e 2{) a function of T. This is done in Figs. 41 and 
which may be said to be the final result of the calibration problem 
hand. Fig. 41 contains the data of Group I, Fig. 42 the data of Group 
In Fig. 41 numerals inserted show the series to which the point of 
;ervation refers. If temperature be increasing (heating) the numeral 
daced above the point; if temperature be decreasing (cooling) the 
neral is below the point. In Fig. 42 similar distinctions are carried 
by caudal dashes. For increasing temperature these point upward 
to the right ; for decreasing temperature downward or to the left. 
CONSTANT-PRESSURE THERMOMETER— DISCUSSION. 
Errors of measurement in general. — The discussion of the data, Tables 
to 75, may expediently be introduced by an analysis of the effect of 
ors. The divers quantities, which enter saliently into the equation, 
ived for constant- pressure air thermometry, are here 
t 7 T h 
Vi 
T 9 
H Q 
which may be added M and S. As above, the degree of absolute ac- 
acy with which they are to be measured in order that the effect on 
hay not exceed 1 : 1000, follows from the equation 
~ _dx 
6x ~dT 
T 
1000 
ere x typifies any one of the quantities enumerated. From this fol- 
the subjoined special equations, all of which are approximate, and 
in such forms as will best facilitate the computation : 
6M-. 
1000(l + aZT 
(881) 
