water-line is _additive_ in the former case, _subtractive_ in the
latter. Its amount may be taken, nearly enough, by allowing 0·001 in. of
the barometer for each foot of difference of level.

An example of the application of these several corrections is
subjoined:--


| _Attached Therm_. 54°·3. |_Data for the correction of |
| | the Instrument_. |
+---------------------------------------+-------------------------------+
|Barometer reading. 29·409 |Neutral point 30·123 |
|Corr. for capacity - ·017 |Capacity 1/42 |
| |Capillary action + ·032 |
+---------------------------------------| |
| 29·392 |Zero to Royal Society + ·036 |
|Corr. for capillarity + ·032 |Corr. for altitude above |
| | water-line + ·004 |
+---------------------------------------| |
| 29·424 | |
|Corr. for temperature - ·068 | |
+---------------------------------------| |
| 29·356 | |
|Corr. for zero and water-line + ·040 | |
+---------------------------------------| |
|Aggregate = pressure at | |
| sea-level 29·396 | |
+---------------------------------------+-------------------------------+