SEA. 



of a very elegant kind, but this vanidiea while he admires 

 it. A piece of c<;ral, or other hard lubftance, thus coated 

 over, appears, as it rifes to the lurface of the water, of a 

 delicate green, blue, or purple ; but when taken above 

 ■water it is found that this fine colour is only in the coat of 

 glue or jelly which covers the fubllance ; as foon as this is 

 wiped off, the colour is carried away with it, and the coral 

 Ihews its own native tinge ; and it is to no purpole to attempt 

 the preferving of it, by fufFering this glue to dry upon the 

 coral, for the colour flies away by degrees, as the moifture 

 evaporates, and the coral. Sec. whatever it be, is only fo 

 much the lefs beautiful, than it naturally would have been, 

 as it is covered with a dry yellowifh dirty looking horny 

 matter. Thefe are beauties in the fub-marine produdlions, 

 therefore, which can be only feen by thofe who venture out 

 in order to take them up. 



The imall quantities of thefe elegant colours, which we 

 thus find fpread over the furfaces of marine bodies, as we 

 approach deep water, may give a rational idea of what we 

 Ihould find, were we able to examine the bottom of the fea 

 in its deep and unfathomable receffes. It is eafy to con- 

 ceive, that in thefe places wc fhould find great quantities of 

 the moft beautiful fubftances. Marfigli, Hift. Phyf. de la 

 Mer. 



Dr. Donati, in an Italian work, containing an eflay to- 

 wards a natural hiftory of the Adriatic fea, printed at Ve- 

 nice in 1750, has recited many curious oblervations on this 

 fubjeft, and which confirm the above account of Marfigli ; 

 having carefully examined the foil and produftiona of the 

 various countries that furround the Adriatic fea, and com- 

 pared them with thofe which he took up from the bottom 

 of the fea, he found that there is very little difference 

 between the former and the latter. At the bottom of the 

 water there are mountains, plains, vaUies, and caverns, 

 fimilar to thofe upon land. The foil confills of different 

 flrata placed one upon another, and for the moll part parallel 

 and correfpondent to thofe of the rocks, iflands, and neigh- 

 bouring continents. They contain iloncs of different forts, 

 minerals, metals, various putrified bodies, pumice-flouL- and 

 lavas formed by volcanoes. 



The adjacent countries, as well as the bottom of the 

 Adriatic fea, confifl of a mafs of a whitifh marble, of an 

 uniform grain, and of almoft an equal hardnefs ; and this 

 marble, in many places under both the earth and fea, is in- 

 tercepted by feveral other kinds of marble, and covered by 

 a great variety of bodies, fuch as gravel, fand, and earths 

 more or lefs fat. To this variety of foils, he afcribes the 

 varieties obferved with refpedt to the nature and quantity of 

 plants and animals found at the bottom of the fea. 



One of the objedls which mod excited his attention, was a 

 cruft, which he difcovered under the water, compofed of 

 cruftaceous and teftaceous bodies, and beds of polypes of 

 different kinds, confufcdly blended with earth, fif.id, and 

 gravel ; the different marine bodies, which form this cruft, 

 are found at the depth of a foot or more, entirely petrified 

 and reduced into marble ; thefe, he fuppofes, are naturally 

 placed under the fea when it covers them, and not by means 

 of volcanoes and earthquakes, as fome have conjectured. 

 On this account, he imagines, that the bottom of the fea is 

 conflantly rifing higher and higher, with which other ob- 

 vious caufes of increafe concur ; and from this rifing of the 

 bottom of the fea, that of the level of the water naturally re- 

 fults ; in proof of which this writer recites a great number 

 of fads. Philofoph. Tranf. vol. xlix. p. 5S5, &c. 



Sea, Dead. Dr. Perry made feveral experiments on the 

 water of the Dead fea, in order to find what particles it 

 contained. Upon infufing fome fcrapings of galls in it, it 



becomes of a bright purple colour, but that not till it has 

 flood a confiderable time. On adding oil of tartar per deli- 

 quium to it, it becomes turbid, and looks as if globules of 

 fat were fluftuating in it ; this unttuous matter, upon its 

 long Handing in repofe, comes together in form of a fedi- 

 ment at the bottom. On pouring fpirit of vitriol into it, it 

 depofits a milk-white grealy fediment, which, after Handing 

 twelve hours, occupies about one-fif'lli part of the liquor. 

 On putting a fmall quantity of (acclianini faturni to it, it de- 

 pofits a fmall quantity of a greyifh powder ; being feverally 

 and feparately mixed witii a folution of fublimati.-, with fpirit 

 of fal ammoniac, and with fugar of violets, it neither fer- 

 ments nor depofits any fediment, nor changes colour, except 

 with the fugar of violets, with which it becomes green. 



It is hi^ly faturated with fait, fo that it is to common 

 water in fpecific gravity, as five to four j and it has fo acrid 

 and llyptic a tafle, that on being held in the mouth, it con- 

 ftringes it in the manner of alum. 



It appears, that this water is impregnated with a fort of 

 an acrid and alkaline nature, and a matter partly of a ful- 

 phureous, partly of a bituminous nature. Philof. Tranf. 

 N^ 462. p. 50. For the obfervations of other writers on 

 this fubjecl, fee Asphaltite lake, and Dead Sea. 



Sea, lum'inoufnefs of the, is a phenomenon that has been 

 taken notice ot by many nautical and philofophical writers. 

 Mr. Boyle, after reciting feveral circumflances attending 

 this appearance, afcribes it to fome cofmical law, or cullora 

 of the terreftrijil globe, or at leafl of the planetary vortex. 



Father Bourzes, in his voyage to the Indies, in 1704, 

 took particular notice of this phenomenon, and very minutely 

 defcribcs it, without affigning the true caufe. 



The abbe Nollei was long of opinion, that the light of the 

 fea proceeded from eleftricity, and others have had recourfe 

 to the fame hypothefis. M. Bayon, in his " Nfemoires pour 

 fervir a I'Hiiloire de Cayenne, &c." Paris, 1778, informs 

 lis, that, having made a great number of experiments, in 

 different feafons, in order to find out the true caufe of this 

 phenomenon, he always found, that the luminous points in 

 the finface of the fea were produced merely by friciion. 



However, there have been two hypothefes, which have 

 raofl generally been received, fur the folution of this pheno- 

 menon ; one of which afcribes it to the (hining of luminous 

 iiifedls or animalcules, and the other to the ligiit proceeding 

 from the putrcfadion of animal fnbltances. The abbe 

 Nollet, who at firll confidered the luminoufnefs of the fea as 

 an eleftrical phenomenon, having liad an opportunity of 

 afcertaining the circumllances of it, when lie was at Venice 

 in 1749, relinquifhed his former opinion, and concluded that 

 it was occafioncd either by the luminous afpctt, or by fome 

 liquor or effluvia of an infed which he particularly dcfcribes ; 

 but does not altogether exclude other caufes, and efpecially 

 the fpawn or fry of fi(h. 



The fame hypothefis had alfo occurred to M. Vianelli, 

 profellor of medicine in Chioggia near Venice ; and both he 

 and M. Grizellini, a phyficiaii in Venice, have given draw- 

 ings of infefts from whicii they imagined this light to pro- 

 ceed. 



A fimilar conjedure is propofed by a coirefpondrnt of 

 Dr. Franklin, in a letter read aX the Royal Society in 1 756 ; 

 the writer of which ap;)rehends, that this appearance may be 

 caufed by a great number of liulc animals, floating on the 

 furface of the fea, which, on being diflurbed, iniijht, by ex- 

 panding tlieir fins, or otherwifc nviving themfclves, cxpofc 

 Inch a pan of their bodies a? exhibits a luminous appearance, 

 fomewhat in the manner of a glow-worm, or fire-fly i that 

 tliefe animals may be more numerous in fome places than 

 others, and, therefore, that the appearance above- men- 

 tioned, 



