Transactions of the Geological Society, 1st series, vol. 4/Barometrical Measurements

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Barometrical Measurements
William Allen and Samuel Woods




XIX. Barometrical Measurements.


By WILLIAM ALLEN, F.R.S


member of the geological society.


[Read 19th November, 1812.]


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\scriptstyle \frac 12 hours 0.09 inches, and from observations 2 & 5 that it had fallen at Llyn Cader in 6\scriptstyle \frac 14 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.

Feet.
From Observations 6 and 7, the height of Beddgelert Inn above high water-mark = 162.7
From Observations 1 & 4, the height of Llyn Cwellyn above Beddgelert = 314.2
above the Sea = 476.9


From Obs.
1 & 2
From Obs.
1 & 3
mean
The height of Llyn Cader above Beddgelert 489.3 480.2 484.7
above the Sea 652. 642.9 647.4
From Obs.
1 & 3
From Obs.
3 & 7
mean
The height of Snowdon above Beddgelert 3457.5 3409. 3433.2
above the Sea 3620.2 3571.7 3595.9


In the following measurements only one observation was made at the lower station, unless the contrary is stated.


Cader Idris.
The height of the highest Peak above Dollgellau 2879
The height of the highest of the three Heads above Dollgellau 2840
Ingleborough
The height of Ingleborough above the Bay-horse Inn, Ingleton 1881
Ingleton is 90 feet below Settle; the height of Settle has been accurately taken, and is stated at 621 above the sea; therefore the height of Ingleton above the sea is 531
and the height of Ingleborough above the sea is 2412
Whernside
The height of Whernside above Ingleton 1930
above the sea 2461
Pen-y gant.
The height of Pen-y gant above Settle 1858
above the sea 2479
Shap Fells.
The height of the highest point in the road between Kendal and Shap above Kendal 1187

Helvellyn.
From two observations made the same day at Paterdale.—Day rainy.-The Barometer varied .194 in 5 hours.—The Inn at Paterdale is 24 feet above Ullswater.
The height of Grisdale brow above Ullswater 988
──── of RedTarn 1935
──── of the top of Helvellyn 2686
Saddleback.
Threlkeld, where the first observation was made, is 235 feet above the level of Keswick Lake, which is 228 feet above the sea.
above Keswick Lake. above the Sea
The height of Saddleback—the Pummel 2615 2843
the Crupper 2561 2789
Skiddaw.
The Oak Inn at Keswick, where the first observation was made, is 28 feet above the lake, which is 228 feet above the sea.
above Keswick Lake. above the Sea
The height of Latrigg 330 558
of Half-way stone 1408 1636
of the summit of Skiddaw 2789 3017
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XIX. Barometrical Measurements.


By SAMUEL WOODS, Esq.

member of the geological society.

[Read 19th November, 1812.]


In the following measurements only one observation was made at the lower station, unless the contrary is stated. They are calculated according to the formula of Sir Henry Englefield.

Branch of the Mendip hills just above and eastward of Cross; the point appears to the eye to be one of the highest in the Mendip range. Height above Cross 670

Helvellyn.
Height above the sea
Feet
Dunkerry Beacon, one of the highest points of Exmoor, near Minehead. Weather cloudy, with light rains. From two observations, one at Porlock Quay, the other at Minehead Quay, the Barometer had fallen 0.14 inches in 5 hours 1784
Top of Brendon hills in the road between Minehead and Dulverton 1210
North hill above Minehead 1000
Highest point in the road between Barnstaple and Ilfracomhe 900
Linton Church-yard, in the North of Devonshire 428
Exmoor, about 4 miles south of Linton; one of the highest points on the Devonshire side of Exmoor 1608
Hill called Hangman, near Comb-Martin 1093
Hill about 1 mile east of the Hangman 1168
Yester, near Okehampton, one of the highest points of Dartmoor, above the Inn at Okehampton, 1561 feet 2077
The height of the Inn at Okehampton 516
Hastings, Sussex.
General Roy's station near the Windmill on Fairlight Common 588
East Cliff 190
Hill above the East Cliff 313
Castle Hill 180
Castle Cliff 135
Dover.
Western height 382
Shakespear's Cliff 310
Summit of Castle-hill, beyond the turnpike 390
Dorking, Surry.
Heights above the bed of the Mole.
Feet
Box-hill about 300
Headley Church, and the highest part of the wood on Mickleham Downs 466
Norbury park 292
Bench beyond the summit of the park 320
Leith hill tower 803
Beech Trees on the south side of Headley Common 585