82 Captain Kater on the comparison of 
Third comparison. Thermometers as before. 
Readings. 
Forty inch bar 
« fist interval 
2d. 
<*> . 
z . 3d- 
0 < 4th- 
1 5th. 
cS l 6th - 
Mean 
Forty inch bar. 
35>° 
Div. 
Mean of Ramsden’s bar 3 9,6 
of forty inch bar 35,6 
Forty inch bar longer 4,0 
58,7 
3°,° 
3 1 * 0 
44>° 
3f>° 
4°>° 
3 9, 6 
36,2 
By the mean of these comparisons, it appeared that the 
forty inch bar was too long 2,9 divisions of the micrometer, or 
,000124, of an inch.* 
The preceding measures were taken from the middle of 
the lines on the gold pins ; but as it was found that these 
lines were not quite parallel, this accidental circumstance 
afforded a method, of which I availed myself, to attain a 
greater degree of accuracy. 
The deviation of the two lines was obtained by measuring 
the difference of the distances of their extremities, and by the 
mean of six comparisons was found to be 16,8 divisions. 
Now, as this is the deviation due to the whole length of the 
lines, they will have approached each other 2,9 divisions, at 
about one sixth part of their length, reckoning from their 
most distant extremities. 
* Each division of the micrometer is °f an i nc F 
