Old Cumbria Gazetteer

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	place:-	floating island, Derwent Water
	site name:-	Derwent Water
	parish	Keswick parish, once in Cumberland
	county:-	Cumbria
		island
	coordinates:-	NY2619
	10Km square:-	NY21
	1Km square	NY2619
	source:-	Martineau 1855
		Guide book, A Complete Guide to the English Lakes, by Harriet Martineau, published by John Garnett, Windermere, Westmorland, and by Whittaker and Co, London, 1855; published 1855-71.
		Page 75:-
		... The Floating Island, whose appearance is announced in the newspapers at intervals of a few years, has obtained more celebrity than it deserves. It is a mass of soil and decayed vegetation, which rises when distended with gases, and sinks again when it has parted with them at the surface. Such is the explanation given by philosophers of this piece of natural magic, which has excited so much sensation during successive generations. Sometimes it comes up a mere patch, and sometimes measuring as much as an acre.
	date:-	1855
	period:-	19th century, late; 1850s
	descriptive text:-	Ford 1839 (3rd edn 1843)
		Description of Scenery in the Lake District, by William Ford, published by Charles Thurnham, London, et al, 1839; published 1839-52.
		Page 54:-
		... Of the Floating Island, or rather rising and sinking Island, the account given by Mr. Otley is perhaps best and most plausible; as an object of interest, however, it is worth nothing to the tourist.
	person:-	: Otley, Jonathan
	date:-	1839
	period:-	19th century, early; 1830s
	descriptive text:-	Otley 1823 (5th edn 1834)
		Guidebook, Concise Description of the English Lakes, later A Description of the English Lakes, by Jonathan Otley, published by the author, Keswick, Cumberland, by J Richardson, London, and by Arthur Foster, Kirky Lonsdale, Cumbria, 1823 onwards.
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		Page 18:-
		...
		Besides ... permanent islands, an occasional one is sometimes observed, called the Floating Island: being a piece of earth, which at uncertain intervals of time rises from the bottom to the surface of the lake [Derwent Water]; but still adhering by its sides to the adjacent earth, is never removed from its place.
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		Page 19:-
		Within the last thirty years it has emerged eight times; remaining upon the surface for longer or shorter periods. In a succeeding part of this work the discussion of this subject will be resumed at greater length.
		...
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		Page 171:-
		THE FLOATING ISLAND IN DERWENT LAKE.
		THE existence of this phenomenon has been doubted by some persons; while others, admitting the fact, have contended that the term Floating Island was improperly applied to this subject, as it never changes its situation - being still attached by its sides to the adjacent earth under water. Its occasional appearance, however, is ascertained beyond a doubt; and Floating Island being the name by which it has always been known, there can be no manifest impropriety in retaining the appellation.
		It is situated in the south-east corner of the lake, not far from Lowdore, about 150 yards from the shore, where the depth of the water does not exceed six feet in a mean state of the lake. It has been said to make its appearance once in seven years, but this is quite uncertain; it generally rises after an interval of a few years, and towards the conclusion of a warm summer. Its figure and dimensions are variable; it has sometimes contained about half an acre of ground, at other times only a few perches: but extending in a gradual slope under water, a
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		Page 172:-
		much greater portion is raised from the bottom than reaches the surface of the lake. Several large rents or cracks may be seen in the earth about the place, which appear to have been occasioned by its stretching to reach the surface. It never rises far above the level of the lake; but having once attained the surface, it for a time, fluctuates with the rise and fall of the water; after which it sinks gradually. When at rest in the bottom of the lake it has the same appearance as the neighbouring parts, being covered with the same vegetation, consisting principally of Littorella lacustris, interspersed with Lobelia dortmanna, Isoetes lacustris, and other plants common in this and all the neighbouring lakes: after remaining some time above the water its verdure is much improved. For a few inches in depth it is composed of a clayey or earthy matter, apparently deposited by the water, in which the growing plants have fixed their roots; the rest is a congeries of decayed vegetable matter forming a stratum of loose peat earth about six feet in thickness; which rises from a bed of very fine soft clay. A considerable quantity of air is contained in the body of the island, and may be dislodged by probing the earth with a pole. This air has been found by Dr. Dalton to consist of equal parts of carburetted hydrogen and azotic gasses, with a little carbonic acid.
		For the last quarter of a century the times of its appearance have been as follows. In 1808 from the 20th July to the beginning of October; in 1813
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		Page 173:-
		from the 7th September to the end of October; in 1815 from the 5th to the end of August; in 1819 from the 14th August to the end of that month; in 1824 from 21st June to the end of September; in 1825 it was above water from the 9th to the 23rd of September; and in 1826 from the 11th July to the end of September: the uncommon circumstance of its appearing in three successive years may be attributed to the extraordinary warmth of the seasons. It rose above water again on the 10th June 1831 and remained uncovered till the 19th July.
		It would be tedious to investigate every hypothesis which has from time to time been put forth to account for this phenomenon - with the arguments for and against each - some assuming water, others air, as the chief agent in its production.
		A small mountain stream which pours down a rock opposite the place, and runs underground before it reaches the lake, has been employed in various ways to account for its rising; and many a supposition has been advanced, of the way in which air might be conveyed or generated underneath it.
		On material circumstance has however generally escaped observation: namely, that the air to which the rising of this island has been attributed, is not collected in a body underneath it; but interspersed through the whole mass: not causing it to float 'as a reversed saucer would in a bowl of water;' but by enlarging its bulk, and thereby diminishing its specific gravity. And the most probable con-
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		Page 174:-
		[con]clusion seems to be, that air or gas is generated in the body of the island by decomposition of the vegetable matter of which it is formed; and this gas being produced most copiously, as well as being more rarified in hot weather, the earth at length becomes so much distended therewith, as to render the mass of less weight than an equal bulk of water. The water then insinuating itself between the substratum of clay and the peat earth forming the island, bears it to the surface, where it continues for a time; till, partly by escape of the gas, partly by its absorption, and partly by its condensation consequent on a decrease of heat, the volume is reduced; and the earth gradually sinks to its former level, where it remains till a sufficient accumulation of gas again renders it buoyant.
		But as the vegetable matter of which the island is principally composed, appears to have been amassed at a remote period, when the lake was of less depth than at present, receiving very little addition from the decay of plants recently grown upon the spot; it is reasonable to suppose that the process furnishing the gas cannot from the same materials be continued ad infinitum: but that there must be a time when it shall have arrived at its maximum: after which the eruptions will become less extensive or less frequent.
	date:-	1823
	period:-	19th century, early; 1820s
	old map:-	Clarke 1787 map (Der)
		Map series, lakes and roads to the Lakes, by James Clarke, engraved by S J Neele, 352 Strand, London, included in A Survey of the Lakes of Cumberland, Westmorland and Lancashire, published by James Clarke, Penrith, and in London etc, from 1787 to 1793.
		Floating Island
		island
	date:-	1787
	period:-	18th century, late; 1780s
	hearsay	The island was 25 x 88 yards when it rose in 1815, the largest ever recorded. It rose and stayed up for more than 14 weeks in 1831.
	Old Cumbria Gazetteer - JandMN: 2008

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