299 
trigonometrical measurements at Spitsbergen. 
displacement of the scale, or a diminution of mercury in the 
cistern. The subjoined comparisons will show that an altera- 
tion, amounting to 0.129 parts of an inch, being supposed to 
have taken place since the first comparison, making the 
index correction of Mr. Jones’s -f» 0.196, and its neutral 
point 30.271, will reconcile all the comparisons within such 
limits as may readily be allowed as errors of observation. 
The mean difference of fourteen comparisons thus reduced is 
less than four ten-thousandths of an inch ; whence it is rea- 
sonable to conclude, that from the same number of observa- 
tions, made under similar circumstances, the height of New- 
man’s barometer may be inferred from that of Jones’s, and 
vice versa, to an equal degree of exactness. 
The table of comparisons shows the actual readings of the 
two barometers, corrected only for the expansion of mer- 
cury and of the scale to a mean temperature of 32 0 ; the last 
column exhibits the differences in excess or defect, of Jones’s 
on Newman s, after the application of their respective correc- 
tion for capacity, capillary action, and an index error of 
+ 0.196. 
Newman’s. Jones’s. 
Biff . 
Hammerfest, June io. 
30.1 16 
30.002 
+.003 
Spitzbergen, July 12, 
29.890 
29.79 1 
+ .003 
- 
- 
29.867 
29.764 
—.003 
- 
- » 3 > 
29.857 
29-757 
—.001 
- 
- l 3 > 
29.864 
29.762 
—.002 
- 
- * 3 > 
29.860 
29.765 
+ .005 
- 
- » 4 . 
29.888 
29.783 
—.003 
- 
- H> 
29.910 
29.798 
— .010 
- 
- I 5 > 
29.937 
29.826 
— .006 
- 
- 
29.885 
29.784 
000 
m 
- 16, 
29.811 
29.715 
000 
- 
- 16, 
29.756 
29.666 
+ .003 
- 
- 
29.698 
29.611 
+ .002 
2 
- 1 7 > 
29.721 
29- 6 33 
+ .003 
Mean difference, Jokes’s in 
defect .0004 nearly 
