SEA. 



tioned, being fainter and ftronger in different places, might 

 be owing to this caufe ; and that certain circiimltances of 

 weather, &g. might invite them to the furface, on which, in 

 a calm, they might fport themfelves and glow, or in ftorms, 

 being forced up, make the fame appearance. 



Mr. Foiler, in his account of a voyage round the world 

 with captain Cook, in the years 1772, 1773, I774) and 

 177c, deferibing this phenomenon as a kind of blaze of the 

 fea, and having attentively examined fome of the illumined 

 water, expreffes his conviftion, that the appearance was oc- 

 caiioned by innumerable minute animals of a round fhape, 

 moving through the water in all diredlions. One of thefe 

 luminous fparks, which iluck to liis finger while he was ftir- 

 ring his water with his hand, was examined by the common 

 magnifier of Mr. Ramfden's improved microfcope, and was 

 found to be globular, tranfparent like a gelatinous iubltance, 

 and fomewhat brownifh ; by means of the greatell magnifier, 

 the orifice of a little tube was difcovered, which entered the 

 body of the animal ; within w-hich were four or five inteftinal 

 bags connefted with the tube. He imagines that thefe ani- 

 malcules may be the young fry of fome fpecies of medufa, 

 or blubber, and confi Jers them as poffefled of the power of 

 fhining, or of withholding their light at pleafure. 



M. Dagelet, a French aitronomer, failing into the bay of 

 Antongil, in the ifland of Madagafcar, obferved a pro- 

 digious quantity of fry, which covered the fea above a mile 

 in length, and which he at firft took for banks of fand, on 

 account of their colour ; they exhaled a difagreeable odour, 

 and the fea had appeared with uncommon fplendour fome 

 days before. On another occafion, having perceived the 

 fea to be remarkably luminous in the road of the Cape of 

 Good Hope, during a perfeft calm, he remarked that the 

 oars of the canoes produced a whitifh and pearly kind of 

 lullre ; when he took in his hand the fhining water, he dif- 

 cerned in it, for fome minutes, globules of light as large as 

 the heads of pins ; upon preffing thefe, they teemed to be a 

 foft and thin pulp, and fome days after the fea was covered, 

 near the coafts, with whole banks of thefe little fifh in innu- 

 merable multitudes. 



M. Dagelet, in his return from the Terra Aultralis in 

 1774, brought with him fcveral kinds of worms, which 

 ihine in water when it is fet in motion ; and Mr. Rigaud 

 affirms, that the luminous furface of the fea, from the port of 

 Breft to the Antilles, contains an immenfe quantity of fmall, 

 round, fhining polypufes. 



M. le Roi, after giving much attention to this phenomenon, 

 concludes that it is not occafioned by any fhining infefts, 

 efpecially as, after carefully examining with a microfcope 

 lome of the luminous points, he found them to have no ap- 

 pearance of any animal ; and he alfo found, that the mixture 

 of a little fpirit of wine with water jull drawn from the fea, 

 would give the appearance of a great number of little fparks, 

 which would continue vifible longer than thofe in the ocean ; 

 the fame efFeft was produced by all the acids, and various 

 other liquors. M. le Roi is far from afferting that there are 

 no luminous infefts in the fea ; for he allows that the abbe 

 NoUet and M. Vianelli had found tliem ; but he is fatisfied 

 that the fea is luminous chiefly on fome other account, 

 though he does not fo much as offer a conjett ure with refpeft 

 to the true caufe. 



Other writers, equally difl'atisfied with the hypothefis of 

 luminous infe<Sls, for explaining the phenomenon, which is 

 the fubjedl of this article, have afciibed it to fome fubllance 

 of the phofphoric kind, arifing from putrefaftion. 



The obfervations of F. Bourzes, above referred to, render 

 it very probable, that the luminoufnefs of the fea arifes from 

 /limy and other putrefcent matter with which it abounds, 



though he does not mention the tendency to putrefaftion, as 

 a circumitance of any confequence to the appearance. 



The correfpondent of Dr. Franklin, part of whofe letter 

 has been already recited, obferves, thit feveral gentlemen <^ 

 have been of opinion, that the feparated particles of putrid, 

 animal, and other bodies, floating on the furface of the fea, 

 might caufe this appearance, for putrid fifh, &c. will caufe 

 it ; and the fea animals which have died, and other bodies 

 putrefied in it fince the creation, might afford a fufficient 

 quantity of thefe particles to cover a confiderable portion 

 of the furface of the fea ; which particles being differently 

 difperfed, might account for the different degrees of light 

 in this appearance ■ but he adds, this account feems liable 

 to an obvious objeftion, viz. that as putrid fifh, &c. make 

 a luminous appearance without being moved or difturbed, 

 it might be expefted that the fuppofed putrid particles on 

 the furface of the fea fhould always appear luminous, when 

 there is not a greater light ; and, confequently, that the 

 whole furface of the fea covered with thole particles fhould 

 always, in dark nights, appear luminous, without being 

 difturbed, which, he fays, is contrary to faft. Frankhn's 

 Experiments and Obfervations, p. 274, S:c. 



This difficulty is, in a great meafurc, removed by the 

 experiments of Mr. Canton, recited in the Philofophical 

 Tranfaftions, vol. lix. p. 446, &c. which have the advantage 

 of being eafily made, and leave no room for doubt, that the 

 luminoufnefs of the fea is principally owing to putrefaftion. 

 Having put a frefh whiting into a gallon of fea-water, 

 neither the whiting, nor the water when agitated, gave any 

 light ; Fahrenheit's thermometer, placed in the cellar where 

 the pan was placed, Handing at 54° : tl-ie following evening, 

 that part of the fifh which was even with the furface of the 

 water was luminous, but the water itfclf was dark ; how- 

 ever, on drawing through it the end of a flick, the water 

 appeared luminous behind the ilick all the way, but gave 

 light only where it was difturbed : when all the water was 

 ftirred, the whole became luminous, and appeared like milk, 

 yielding a confiderable degree of light to the fides of the 

 pan, which it continued to do for fome time after it was at 

 reft. The water was moil luminous when the fifh had 

 been in it about twenty-eight hours, but would give no 

 light by being ftirred after it had been in it three days. He 

 then put a gallon of frelli water into one pan, and an equal 

 quantity of fea-water into another, and into each pan he 

 put a frefh herring, of about three ounces ; the next night 

 the whole lurface of the fea-water was luminous without 

 b?ing ftirred, but much more fo when put in motion, and 

 theupper part of the herring, which was confiderably below 

 the furface of the water, was alfo very bright ; while at 

 the fame time, the frefli water, and tlie fifh that was in it, 

 were quite dark. There were feveral very bright luminous , 

 fpots on different parts of the furface of the fea-water, and 

 the whole, when viewed by the ligiit of a candle, feemed 

 covered with a greafy fcum. The third night the fight of 

 the fea-water, while at reft, was very little, if at all, lefs 

 than before ; but when ftirred, its light was fo great as to 

 difcover the time by a watch, and the fifh in it appeared 

 as a dark fiibftance. After this its light was evidently 

 decreafing, but was not quite gone befoi-e the feventh 

 night ; the frefh water, and the fifh in it, were perfeftly 

 dark during the whole time. The thermometer was gene- 

 rally above 60°. Having made artificial fea-water, deter- 

 mined by an hydrometer to be of the fame fpecific gravity 

 with the fea-water, by adding four ounces avoirdupois of 

 fait to feven pints of water, wine meafure, he put into a 

 gallon of this water a fmall herring ; and another into a 

 gallon of water, in which two pounds of fait had been dif- 



folved 



