XIX. Barometrical Measurements.
By WILLIAM ALLEN, F.R.S
member of the geological society.
The following measurements were made with a single Barometer
of the construction proposed by Sir Henry Englefield, and have been
calculated according to the formula recommended by him in his
memoir on the subject, which is inserted in the 14th volume of
Nicholson's Journal. I shall give in detail the observations made
upon Snowdon; and of the other measurements I shall mention only
the results.
| Snowdon. | ||||||
| Observ. | Hour | September 8th, 1806 | Therm. | Barom. | ||
| 1 | A.M. | 9 | 00 | Goat Inn, Beddgelert | 61 | 29.69 |
| 2 | —— | 10 | 25 | Llyn Cader | 61 | 29.162 |
| 3 | P.M. | 1 | 25 | Summit of Snowdon | 50 | 26.164 |
| 4 | —— | 4 | 00 | Llyn Cwellyn | 56 | 29.30 |
| 5 | —— | 4 | 45 | Llyn Cader | 57 | 29.12 |
| 6 | —— | 6 | 00 | High water-mark at Pont-aber-glas-Llyn | 55 | 29.78 |
| 7 | —— | 6 | 30 | Goat Inn at Beddgelert | 53 | 29.6 |
It appears from observations 1 & 7 that the Barometer had fallen at Beddgelert in 9 hours 0.09 inches, and from observations 2 & 5 that it had fallen at Llyn Cader in 6 hours 0.042 inches. The descent of the mercury may therefore be estimated at about 0.008 inches an hour, for which due correction has been made in each observation on calculating the measurements.
