D I V 
pieces the mole with which the befiegers were endea¬ 
vouring to block up the harbour; and we are told by 
Thucydides, that the Syracufans did the fame thing. It 
feems never to have been afcertained by pofitive fadt 
how long divers can continue under water. Anatomifts 
once believed that perfons in whom the oval opening of 
the heart, or foramen ovale, was not clofed up, could live 
longer than others without breathing, and could, there¬ 
fore, be expert divers. Haller, however, and others, 
have contradicted this opinion ; becaufe people who have 
had that opening have been foon fuffocated, and animals 
who have it not, can live a long time under water: be- 
fides, when that opening is perceptible in grown perfons, 
it is fo fmall as not to be fufficient for that purpofe, efpe- 
cially as the duBus arterinfus is fcarcely ever found open. 
The accounts we have of the celebrity of divers in dif¬ 
ferent countries, are extremely various; and fome of 
them mod probably partake of the marvellous. Gmelin 
informs us, that the divers of Aftracan, employed in the 
fifhery there, can remain only feven minutes underwa¬ 
ter: that they fir ft go into the warm bath, and from 
thence into the cold water, in which, after continuing the 
above time, they are brought back cold and benumbed, 
to the warm bath, from which they return to the cold 
water again. This change from heat to cold they repeat 
five times a-day, until, at length, the blood in many of 
them flows from their nofe and ears, and they are carried 
back quite fenfelefs. The divers in Holland, as we are 
informed by profeflor Beckmann, feem to have been more 
expert. An obferver, during the time they were under 
water, and who endeavoured to hold his breath as long, 
was obliged to breathe, at lead, ten tinles. Thofe who 
colled: pearl-fhells in the Eaft Indies, as Oldenburg re¬ 
lates, can remain under water a quarter of an hour, 
though fome aflert that they continue longer; and Mer- 
fenne mentions a diver, named John Barrinus, who could 
dive under water for fix hours. The natives of Brafil, 
according to Maffaeus, “ will remain feveral hours under 
water, with their eyes open, in order to fearch for any 
thing at the bottom ; r ’ and inftances of the dexterity of 
the favages in diving and fwimming, are noticed by all 
the late circumnavigators, and by moft travellers who 
have vifited the Indian feas. Kircher makes mention 
of a Sicilian diver, named Nicolo Pefce, “ who could 
remain under water for a whole day , and who at laft pe- 
riftied in diving to explore the whirlpool of Charibdis.” 
In Blunt’s account of the Grecian illand Samos, at the 
feet of whofe rocks fponges grow, we are told that “ the 
divers from their infancy are bred up with dry bifcuit., 
and other extenuating diet, to make them extremely lean ; 
then taking a fponge wet with oil, they hold it part in 
their mouths and part without, and thus dive under wa¬ 
ter, where at firft they cannot ftay long, but after due 
practice fome of the leaned will remain an hour and a 
half, or even until all the oil of the fpunge be corrupt¬ 
ed ; and by the law of the ifland, none of that trade is 
fuft'ered to marry, until he have flayed half an hour un¬ 
der water: thus they become able to gather fponges from 
the bottom of rocks more than a hundred fathoms deep.” 
How far thefe different accounts may be true, is not 
for us to enquire : but it has been the opinion of fome 
very eminent modern phyfiologifts, that it is impofiible 
for the human fubjedl, with what practice foever, to re¬ 
main any length of time under water, without fome means 
of inhaling frefh portions of air. For when it is confi- 
dered how fmall the quantity of air mult be, that is con¬ 
tained in the pores of a fponge, and how much that little 
will be contracted by the prefture of the incumbent wa¬ 
ter, it will be obvious that fuch a fupply cannot long 
fultain life : befides, if the depth be considerable, the 
preflure of the water on the bread and organs is fo great, 
that it makes the eyes blood-diotten, and occalions a 
fpitting of blood, which if perllfted in, would quickly 
prove fatal, and often has done fo. On thefe accounts, 
jt is evident^ that men began very early to enter upon 
I N G. gu 
artificial means of aflifling the diver, by contriving modes 
of /applying him with air below, and thereby enabling 
him, without fo much danger or difficulty, to remain a 
longer time under water. With this view the campana 
urinatoria , or diving-bell, was invented. Thofe who had 
no idea of this machine, might have eafily been led to it 
by the following experiment. If a drinking-glafs inverted 
be itnmerfed in water, in fuch a manner that the furface 
of the water may rife equally around the edge of the 
glafs, it will be found that the glafs does not become 
filled with water, even when prefled down to thegreateft 
depth ; for, where there is air, no water can enter, and 
by the above precaution the air cannot be expelled by 
the water. In like manner, if a bell of metal be con- 
ftructed, under which the diver can (land on a ftool fuf- 
pended from it fo that the edge of the bell may reach to 
about his knee, the upper part of .his body will be fe- 
cured from water, and he can, even at the bottom of the 
fea, breathe the air inclofed in the bell. The invention 
of this bell is generally afligned to the lixteenth century ; 
and indeed it feems but little known before that period. 
We read, however, that fo early as the time of Ariftoile, 
divers ufed a kind of kettle, to enable them to continue 
longer under the water; but the manner in which it was 
employed is not clearly defcribed. 
The oldeft information we have refpedting the ufe of 
the diving-bell, in Europe, is that of John Taifnier, who 
was born at Hainault in 1509, and had a place at the 
Spanilh court under Charles V. whom he attended on 
his voyage to Africa. He relates the fact as follows : 
“ Were the ignorant vulgar told that one could defcend 
to the bottom of the Rhine, in the midft of the water, 
without wetting one’s clothes, or any part of one’s body, 
and even carry a lighted candle to the bottom of the wa¬ 
ter, they would confider it as altogether ridiculous and 
impofiible. This, howevair, I faw done at Toledo, in 
Spain, in the year 1538, before the emperor Charles V. 
and almoft ten thoufand fpeftators. The experiment was 
made by two Greeks, who taking a very large kettle, 
fufpended from ropes with the mouth downwards, fixed 
beams and planks in the middle of its concavity, upon 
which they placed themfelves, together with a candle. 
The kettle was equipoifed by means of lead fixed round 
its mouth, and by which it was funk to the bottom; yet 
the men came up again without being w'et, and with the 
candle burning.” It appears that this art was then new 
to the emperor and the Spaniards, and that the Greeks 
were caufed to make the experiment, in order to prove 
the poflibility of it. After this period the ufe of the 
diving-bell feems to have become better known. It is 
defcribed more than once in the works of fir Francis 
Bacon, who explains its eftefts, and remarks that it was 
invented to facilitate labour under the water. 
When the Englifh, in the year 1388, difperfed the 
Spanifh fleet, called the invincible armada, part of the 
fliips went to the bottom, near the ifie of Mull, on the 
weftern coaft of Scotland; and fome of thefe, according 
to the account of the Spanifh prifoners, contained great 
riches. This information excited, from time to time, 
the avarice of /peculators, and gave rife to feveral at¬ 
tempts to procure part of the loft treafure, In 1665, a 
perfon was fo fortunate as to bring up fome cannon, 
which, however, were not fufficient to defray the ex- 
pences. Of thefe attempts, and the kind of diving-bell 
ufed, an account has been given by a Scotfman named 
Sinclair; but Pafchius, Leupold, and others, afcribe 
falfely the invention of this machine to that learned man. 
He himfelf does not lay claim to this honour ; but fays 
only, that he converfed with the artift, and meaftired 
the machine. Some years after, attempts of the like 
kind were renewed. William Phipps, the fon of a black- 
fmith, born in America in 1560, and who had been brought 
up as a ihip-carpenter at Bofton, formed a projedt for 
fearching and unloading a rich Spanifh fhip funk on the 
coaft of Hifpaniola; and reprefented his plan in fuch a 
p la liable 
