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cations of the detached thermometers. But the whole subject demands a more thorough investigation. The elasticity of air is affected by moisture as well as heat, although the want of an exact instrument for measuring the former has hitherto prevented its influence from being distinctly noticed.
When the hygrometer which I have invented shall become better known to the public, it may not seem presumptuous to expect, in due time, more correct data concerning the modifications of the atmosphere. Yet, after all, in ascertaining the volume of a fluid subject to incessant fluctuation, it would be preposterous to look for that consummate harmony which belongs exclusively to astronomical science; nor can I help regarding the introduction of some late refinements into the Jormulae for measuring heights by the barometer, which would embrace the minutest anomalies of atmospheric pressure, as rather a waste of the powers of calculation.
I shall now subjoin a concise table of the most remarkable heights in different parts of the world, expressed in English feet. The altitudes measured by the barometer are marked B, while those derived from geometrical operations, and taken chiefly from the observations of Colonel Mudge, are distinguished by the letter G.
Snæ Fiall Jokul, on the north-west point of Iceland, 4558 G
Hekla, volcanic mountain in Iceland, - - 3950 G Sulitelma, in Lapland, - - - 5910 B Snåhätta, ccntre of the Norwegian mountains, - 8 CO B Harebacke, Alpine ridge of Norway, - 4575 B Pap of Caithness, - - - - 1929
Ben Nevis, Inverness-shire, - - - 4.380 B Cairngorm, Inverness-shire, - - - 4080 B Cairnsmuir upon Deugh, Galloway, - - 2597 G Ben Lawers, Perthshire, ... • - - 4015 B Ben More, Perthshire, - - - - 3870 B Schihallien, Perthshire, - - - 3281 G Ben Ledi, Perthshire, - - - - 3009 B Ben Lomond, Stirlingshire, - - - 3240 B Lomond Hills, east and west, Fifeshire, 1466 and 1721 G Soutra Hill, on the ridge of Lammermuir, - 1716 G Coulter Fell, Lanarkshire, - - - 2440 G
Carnethy, high point of the Pentland ridge, - 1700 B
Tintoc Hill, Lanarkshire, - - - - 2806 G Leadhills, the house of the Director of the mines, 1280 B Broad Law, near Crook Inn, Peebles-shire, - 2741 G Queensbery Hill, Dumfries-shire, - - , 2259 G Cairnsmuir of Fleet, Galloway, - - 2329 GHert Fell, near Moffat, - - - 2635 G Dunrich Hill, Roxburghshire, - - - 24.21 G Elden Hills, near Melrose, Roxburghshire, - 1364 G Whitcomb Hill, Peebles-shire, - - 2685 G. Lother Hill, Dumfries-shire, - - 2396 G. Ailsa Rock, in the Firth of Clyde, - - 1103 G Crif Fell, near New Abbey, Kirkcudbright, - 1831 G Kells Range, Galloway, - - - 2659 G Goat Fell, in the Isle of Arran, - - 2865 G. Paps of Jura, south and north, in Argyleshire, 2359 and 2470
Snea Fell, in the Isle of Man, - - - 2004 G South Berule, in Isle of Man, - - 1584 G Macgillicuddy’s Reeks, County of Kerry, - 3404
Sliebh Donard, the highest of the Mourne Mountains, 2786 G Helvellyn, Cumberland, - - - 3055 G. Skiddaw, Cumberland, - - - 3022 G Saddleback, Cumberland, - * - 2787 G Whernside, Yorkshire, - - - 2384 G Ingleborough, Yorkshire, - - - 2361 G Shunnor Fell, Yorkshire, - - - 2329 G Snowdon, Caernarvonshire, - - - 35.71 G Cader Idris, Caernarvonshire, - - - 2914 G Beacons of Brecknock, - - - 2862 G. Plymlimmon, Cardiganshire, - - 2463 G Penmaen Mawr, Caernarvonshire, - - 1540 G Malvern Hills, Worcestershire, - - 1444 G. Cawsand Beacon, Devonshire, - - 1792 G. Rippin Tor, Devonshire, - - - 1549 G Brocken, in the Hartzoforest, Hanover, - - 3690
Priel, in Upper Austria, - - - 7000 B Peak of Lomnitz, in the Carpathian ridge, - S870 B Terglou, in Carniola, - - - - 10390 B Mont Blanc, Switzerland, - - - 15646 G Village of Chamouni, below Mont Blanc, - 3367 G.
Jungfrauhorn, Switzerland, - - 13730
St Gothard, Switzerland, - - 90.75 Hospice of the Great St Bernard, - - 8040 B village of St Pierre, on the road to Great St Bernard, 5338 B Passage of Mont Cenis, - - - 6778 B Gross-Glockner, between the Tyrol and Carinthia, 12780 B Ortler Spitze, in the Tyrol, - - 15430 Rigiberg, above the lake of Lucerne, - - 5408 Dôle, the highest point of the chain of Jura, - 5412 B Mont Perdu, in the Pyrenees, - - 11283
Loneira, in the department of the high Alps, - 14451 Peak of Arbizon, in the department of the high Pyrenees, 8344
Puy de Dome, in Auvergne, - - 4858 G Mont d’Or, - - - - 6202 G. Summit of Vaucluse, near Avignon, - - 2150 Village on Mont Genevre, - - 5945 B. St Pilon, near Marseilles, - - - 3295 G. Soracte, near Rome, - - - 2271 G Monte Velino, in the kingdom of Naples, - 8397 G Mount Vesuvius, volcanic mountain beside Naples, 3978 AEtna, volcanic mountain in Sicily, - 10963 B St Angelo, in the Lipari Islands, - - 5260 Top of the Rock of Gibraltar, - - 1439 B Mount Athos, in Rumelia, - - - 3353 Diana's Peak, in the Island of St Helena, - 2692
Peak of Teneriffe, one of the Canary Islands, - 12358 B Ruivo Peak, the highest point of Madeira, - 5162
Table Mountain, near the Cape of Good Hope, 3520
Cotopaxi, volcanic mountain in the kingdom of Quito, 18890 B Tonguragua, volcanic mountain, near Riobomba, 16579 B Rucu de Pichincha, in the kingdom of Quito, - 15940 B Heights of Assuay, the ancient Peruvian road, 15540 B Peak of Orizaba, volcanic mountain east from Mexico, 17390 G Lake of Toluca, in the kingdom of Mexico, - 12195 B
City of Quito, - • - 9560 B City of Mexico, - - - 7476 B Silla de Caraccas, part of the chain of Venezuela, 8640 B Blue Mountains, in the Island of Jamaica, - 7431 Pelée, in the Island of Martinique, - - 5100 Morne Garou, in the Island of St Vincent’s, - 5050
In this list of altitudes, I have not ventured to insert the Himalaya Mountains, or Great Central Chain of Upper Asia, to which some recent accounts from India would assign the stupendous elevation from 23,000 to 27,000 feet. Such at least are the results of observations made with a small sextant and an artificial horizon, at the enormous distance of 226 or 232 miles, as computed indeed from very short bases. But even with the best instruments, and under the most favourable circumstances, the determination of minute vertical angles is liable to much uncertainty. The progress of accurate observation has uniformly reduced the estimated altitudes of mountains.
I shall conclude with briefly stating the French measures. The Parisian foot was to the English, or the toise to the fathom, as 1,065777 to 1, or nearly as 16 to 15. The metre, or base of the new system, and equal to 39.371 English inches, ascends decimally, forming the decametre or perch, the hectometre, the kilometre or mile, and the myriametre or league, equivalent to 6.213856 of our miles; and descending by the same scale, it forms successively the decimetre or palm, the centimetre or digit, and the millimetre or stroke. The square of the decametre constitutes the are, and that of the hectametre, the hectare or acre, and equal to 2.47 117 English acres. The cube of a metre, or 35.3171 feet, forms the unit of solid mea. sure or the stere, that of a decimetre, or 61.028 inches forming the litre or pint ; and the weight of this bulk of water at its greatest contraction makes the kilogramme or pound, equivalent to 2.1133 pounds Troy, the gramme answering to 15,444 grains.