L I G H T. 
677 
of the Tea, and ftirred it ever To little with his hand in 
the dark, he always faw in it an infinite number of bright 
particles; and he had the fame appearance whenever he 
dipped a piece of linen in the fea, and wrung it in a dark 
place, even though it was half dry; and he obfcrved, that, 
when the fparkles fell upon any thing that was l'olid, it 
would continue Aiming for fome hours together. 
After mentioning feveral circumftances which did not 
contribute to this appearance, this father obferves, that 
it depends very much upon the quality of the water-, and 
lie was pretty Cure that this light is the greateft when the 
water is fatteft, and fulleft of foam. For in the main 
fea, he fays, the water is not every-vvhere Squally pure; 
and that fometimes, if linen be dipped in the fea, it is 
clammy when it is drawn up again ; and he often obferved, 
that, when the wake of the (hip was the brighteft, the wa¬ 
ter was the mod fat and glutinous, and that linen moiAr¬ 
en ed with it produced a great- deal of light, if it was 
flirted or moved brifkly. Befides, in lbme parts of the 
fea, he law a fubftance like fawduft, fometimes red and 
fometimes yellow ; and, w'hen he drew up the water in 
thofe places, it was always vifcous and glutinous. The 
failors told him, that it was the fpawn of whales ; that 
there are great quantities' of it in the north ; and that 
fometimes, in the night, they appeared all over of a bright 
light, without being put in motion by any veil'd or flfli 
palling by them. As a confirmation of this conjecture, 
that the more glutinous the fea-water is, the more it is 
v difpofed to become luminous, he obferves, that one day 
they took a fifii w hich was called a ionite , the infide of 
tlie mouth of which was fo luminous, that, without any 
other light, he could read the fame characters which he 
had before read by the light in the wake of the.(hip; and 
the mouth of this fifii was full of a vifcous matter, which, 
when it was rubbed upon a piece of wood, made it im¬ 
mediately all over luminous; though, when the nioilture 
was dried up, the light was extinguiihed. 
The abbe Nollet was much (truck with the luminouf- 
r.efs of the fea when he was at Venice in 1749 5 and, af¬ 
ter taking a great deal of pains to afcertain the circum¬ 
ftances of it, concluded that it was occafioned by a (hin- 
ing infect ; and, having examined the water very often, 
he at length did find a 1'mall infeft, which he particularly 
defcribes, and to which he attributes the light. The 
fame hypothefis had alfo occurred to M. Vianelli, profef- 
for of medicine in Chioggia near Venice ; and both he 
and M, Grizellini, a phyfician in Venice, have given 
drawings of the inlefts from which they imagined this 
light to proceed. The abbe was the more confirmed in 
his hypothefis, by obferving, fome time after, the motion 
of fome luminous particles in the fea ; for, going into 
the water, and keeping his head juft above the furface, 
he faw them dart from the bottom, which was covered 
with weeds, to the top, in a manner which he thought 
very much refembled the motions of infefts; though, 
when he endeavoured to catch them, he only found fome 
luminous fpots upon his handkerchief, which were enlarged 
when he prefled them with his finger. 
M. le Roi, making a voyage on the Mediterranean, 
prefently after the abbe Nollet made his obfervations at 
Venice, took notice, that in the day-time the prow of 
the (hip in motion threw up many fmall particles, which, 
falling upon the water, rolled upon the furface of the fea 
for a few leconds before they mixed with it; and in the 
night the fame particles, as be concluded, had the ap¬ 
pearance of fire. Taking a quantity of the water, the 
fame'fmall fparks appeared whenever it was agitated*; but, 
as was obferved with refpetft to Dr. Beale’s experiments, 
every fuccefiive agitation produced a lefts effedt than the 
preceding, except after being fullered to reft awhile ; for 
then a frefh agitation would make it almoft as luminous 
as the firft. This water, he obferved, would retain its 
property of fhining by agitation a-day or two ; but it 
difappeared immediately upon being feton the.fire, though 
it was not made to boil. This gentleman, after giving 
Vot.. XII. No. S62. 
much attention to this phenomenon, concludes, that, it is 
not occafioned by any (billing infects, as the abbe Nollet 
imagined ; efpeCially as, after carefully examining fome 
of the luminous points, which he caught upon a handker¬ 
chief, he found them to be round like large pins’ heads, 
but with nothing of the appearance of any animal, 
though he viewed them with a microfcope. He alfo 
found, that the mixture of a little ftpirit of wine with wa¬ 
ter juft drawn from the fea, would give the appearance of 
a great number of little fparks, which would continue 
v 1 (I’ole longer than thofe in the ocean. All the acids and 
various other liquors, produced the fame effect, though 
not quite fo confpicuoufly; but no frefii agitation would 
make them luminous again. M. le Roi is far from aflert- 
ing that there are no luminous infedts in the fea. He 
even fuppofes that the abbe Nollet and M. Vianelli had 
found them. But he was fatisfied that the fea is hunk, 
nous chiefly on fome other account, though he does not 
fo much as advance a conjecture about what it is. 
M.-Ant. Martin made many experiments on the Imht 
of fillies, with a view to difcover the caufe of the lighfof 
the lea. He thought that he had reafon to conclude, 
from a great variety of experiments, that all fea-fifhes 
have this property ; but that it is not to be found in any 
that are produced in frefii water. Nothing depended 
upon the colour of the fifiies, except that he thought that 
the white ones, and efp.ecially thole that had white fcales, 
were a little more luminous than others. This lip-ht, he 
found, was increafed by a fmall quantify of fait ; and 
alfo by a fmall degree of warmth, though a greater de¬ 
gree extinguifiied it. This agrees with another obferva- 
tion of his, that it depends entirely upon a kind of 
moifture which they had about them, and which a fmall 
degree of heat would expel, when an oilinefts remained 
which did not give this light, but would burn in the fire. 
Light, from the fie'fii of birdslor bealts is not fo bright, he 
lays, as that which proceeds from fifii. Human bodies, 
lie fays, have fometimes emitted light about the time that 
they began to putrefy ; and the walls and roof of a place 
in which dead bodies had often been expofed, had a kind 
of dew or clamminefs upon them which was fometimes lu¬ 
minous ; and he imagined that the lights which are faid 
to be feen in burying-grounds may be owing to this caufe. 
From fome experiments made by Mr. Canton, he con¬ 
cludes, that the Inminoufnefs of fea-water is owing to the 
fiiniy and other putrefcent fubftances it contains. "On the 
evening of the 14th of June, 1768, he put .a fmall frefii 
whiting into a gallon of lea-water, in a pan which was 
about fourteen inches in diameter, and took notice that 
neither the whiting nor the water, when agitated, gave 
any light. A Fahrenheit’s thermometer, in the cellar 
where the pan was placed, flood at 54 0 . On the 15th, at 
night, that part of the fifii which was even with the fur- 
face of the water was luminous, but the water itfelf was 
dark. He drew the end of a flick through it, from one 
fide of the pan to the other; anu the water appeared lu¬ 
minous behind the flick all the way, but gave light only 
where it was difturbed. When all the water was llirred, 
the whole became luminous, and appeared like milk, giv¬ 
ing a coniiderable degree of light to the (ides of tile pail; 
and it continued to do fo for fome time after.it was at 
reft. .The water was moll luminous when the fifii had 
been in it about twenty-eight hours ; but would not give 
any light by being ftirred, after it had been in it three 
days. He then nut a gallon of frefii water into one pan, 
and an equal quantity of fea-water into another; and 
into each pan he put a frefii herring of about three ounces. 
The next night the whole furface of the fea-water was 
luminous without being ftirred; but it was much more fo. 
when it was put in motion ; and the upper part of the 
herring, which was confiderably below the furface of the 
water, was alfo very bright; while at the fame time the 
frefti water, and the fifth that was in it, were quite dark. 
There were feveral very bright luminous fpots* on differ¬ 
ent parts of the furface of the fea-water; and the whole, 
8 K when 
