Remarks on Elasticity. 
87 
The height of the barometers being expressed in metres makes no difficulty. It 
is of no consequence in what linear measure they are given, provided they be both 
given in the same. The rule requires, however, that the temperatures should be 
expressed in Fahrenheit’s scale, and accordingly the indications of the centigrade 
thermometer, as given by Puissant, have been reduced to that scale as above. 
1. To reduce the mercurial columns to the same temperature we have, 
,735 Jr 16,' “1 
= ,0000735+16,1 = ,001176 
10,000 
And ,73558 — , 001 18 = ,7344 the corrected length of the mercurial column. 
The correction is subtracted because the barometer ,73558 was the wanner. 
The two barometers being ,7344 
,5378 
Their sum is 1,2716 
Their difference ,1972 
Half their diff. = ,8986 and removing decimal point 
5 places to the right it will be — 9860 
Dividing by the sum 1,2716 we get 7754 feet, the approximate height or 
difference of level. * 
2. For the corrections. 
Divide 1,2716 the sum by ,1972 the difference, the quotient is 6,45. 
Now divide the approximate height 7754 continually by 8,45 the quotients are, 
1047 1st. 
163 2d. 
25 3d. 
4 4th. 
Now divide the 2d. 4th. 6th. &c. quotients by 3.5.7. &c. for the 1st. 2d, and 
3d. &c. corrections. 
3)163 2nd quotient 
54,3. 1st. correction. 
5)4, 4th quotient 
,8 2d. correction. 
These corrections are always additive. 
Approximate height 7754 
1st. Correction 54.3 
2d. Ditto -8 
Corrected height 7809 1 
3. Correction, for the temperature of the air. 
From the sum of the detached thermometers, — — — 105.6 
Remains .. — 89.3 _ 
Now the corrected height 7809, multiplied by 89’. 3, and divided by 1000 gives 
697,2, adding to this, 69,72 = T ‘ 5 it becomes 766.9 = the correction for the 
temperature of the air. Applying this correction to the approximate height 7809, 
the sum is 8575.9 the true difference of level by barometrical measurement. By 
geometrical methods it was found to be 8573,3, 
IV. Remarks on Elasticity. 
When we say that a body is elastic, we simply mean, that on compressing it, if 
the pressure be removed, the body regains its original volume. 
