100 ReEPORT—1890. 
Tasre 1V.—Value of Flat—H. 
Date Temperature Value 
J) 10:0 15:5 
Chart 1888 15:0 155 
L 20 0 155 
July 1888 a . : : 14:6 14:1 
Jan. 27,1890 . : 3 3 10:0 17:6 
Sven Oe sy 3 : : ; 4:5 VES 
Feb, 4, ” . . . . 60 16°5 
May 31, ,, : : : A 14:1 18°3 
June 10, ,, 5 v ; : 16-0 1871 
divas Rla eas 4 : 5 2 16-0 VET 
June 1%, ,, . . 5 6 16-0 16-4 
June 13, ,, : c ; 16:0 16°8 
LMS SS Sten : - : , 19°0 ner 
Aug. 15, ,, : : 5 4 17-4 17:0 
Aug. 28, ,, ; : ; 17-0 17:8 
Ae. 29), 5, : : 5 L 16:4 18:2 
The first three lines in each table give the differences, at the tempera- 
ture shown, taken from the chart drawn in 1888 ; the remaining lines give 
the differences actually observed, with the dates and temperatures. Thus, 
taking the various coils, itis clear that while up to May 1888 the difference 
between I’lat and F remained the same as shown by the chart and obser- 
vations up to that date, a change took place during the low-tempera- 
ture observations in July 1888, while by the time the coils were again 
examined in January 1890 a further change had manifested itself. This 
continues up to the present date, so that now at temperature of about 
15° the coil F has increased in resistance relatively to Flat by about 
12-7 bridge-wire divisions. This, assuming the whole change to be in F, 
will correspond to a rise of resistance of ‘00063 B.A. unit, or in other 
words the temperature at which the coil is right has failen by about 2°-3. 
In January 1830 the coils were again exposed to a low temperature, and 
it seems probable that the changes took place when the coils were in ice. 
From the values in Table III., which gives the values of Flat—G, we 
see there is no evidence of change till May 1890. The observations in 
July 1888 and January and February 1890 are quite in accordance with 
the chart, but in May 1890 it is clear that G has fallen relatively to Flat. 
The value of the difference at a temperature of 16° is 22°1 b.w.d. as 
against 18°1 given by the chart. Thus G has fallen relatively to Flat by 
4 b.w.d., or ‘0002 B.A. units. This change was first observed after the 
coils had been exposed to a low temperature. 
With regard to H the change first showed itself during the low- 
temperature observations in January and February 1890, and Table IV. 
indicates that the difference between Flat and H is now 17°5 divisions as 
against 15°5 in 1888, or in other words, that G has fallen by ‘OOOL B.A. 
unit. Also since Flat—F changed in 1888, while Flat—G and Flat—H 
did not, we infer that the change at that date was in F, not in Flat; 
while since Flat—H changed in January 1890 without a change in 
Flat—G, it appears that the change was in H, not in Flat; and finally, 
from the observations in May 1890, which show a change in Flat—G 
but never in Flat—H and Flat—F, we infer a change in G. : 
