DIV
t 2 33 ]
DIV
Hence, where there has been Occafion to continue long at the Bottom, fome have contrived double flexible Pipes, to cir- culate Air down into a Cavity enclofing the 'Diver, as with Armour, both to furnifh Air, and to bear off the Preffure of the Water, and give leave to his Breaft to dilate upon Infpira- tion ; The frefti Air being forced down one of the Pipes with Bellows, and returning by the other of 'em, not unlike to an Artery, and Vein.
But this Method is inpracticable when the Depth furpaffes 3 Fathoms ; the Water embracing the bare Limbs fo clofely as to obftruct the Circulation of the Blood in 'em; and with- al preffmg fo llrongly on all the Junctures where the Ar- mour is made tight with Leather ; that if there be the leaft Defect in any of them, the Water rufhes in, and inflantly fills the whole Engine, to the great Danger of the Diver's Life.
The DiviNG-Se//, is a Machine contriv'd to remedy all thefelnconveniencies. In this the Diver is fafely convey'd to any reafonable Depth, and may {lay more or lefs Time under Water, as the Bell is greater or lefs.
'Tis moll conveniently made in Form of a truncated Cone, the fmaller Bale being clofed, and the larger open. It is to be pois'd with Lead, and fo fufpended, that the Veffel may link full of Air, with its open Bans downward, and as near as may be in a Situation parallel to the Horizon, fo as to clofe with the Surface of the Water all at once.
Under this Couverclc the Diver fitting, finks down with the included Air into the Depth defired : And if the Cavity of the Veffel may contain a Tun of Water, a fingle Man may remain a lull Hour, without much Inconvenience, at 5 or 6 Fathoms deep.
But the lower you go, ftill, the included Air contracts it- felf, according to the Weight of theAVater that compreffes it; So as at 33 Foot deep, the 'Bell becomes half full of Water; thePrtffure of the incumbent Water being then equal to that of the Atmofphere : And at all other Depths the Space occu- pied by the compreffed Air in the upper Part of the Sell will be to the under Part of its Capacity fill'd with Water as 33 Feet to the Depth of the Surface of Water in the Sell below the common Surface thereof And this condenfed Air being taken in with the Breath foon infinuates it felf into all the Cavities of the Body, and has no ill Effect, provided the Sell be permitted to defcend fo flowly as to al- low Time for that Purpofe.
One Inconvenience that attends it, is found in the Ears, within which there are Cavities which open only outwards, and that by Pores Co fmall as not to give Ad- miffion even to the Air ir felf, unlefs they be dilated, and diffended by a confiderable Force. Hence, on the firft Defcent of the Sell, a Preffure begins to be felt on each Ear, which, by Degrees, grows painful, till, the Force over- coming the Obftacle, what conlrringe thefe Pores, yields to the Preffure, and letting fome condenfed Air flip in, pre- fently Eafe enfucs. The Sell defcending lower, the Pain is renewed, and again eafed in the fame Manner.
But the greatefl Inconvenience of this Engine, is, that the Water cntring it, contracts the Bulk of Air into fo fmall a Ccmpafs, that it foon heats, and becomes unfit for Rcfpi- ration : So that there is a Keceffity for its being drawn up to recruit it ; befides the uncomfortable Abiding of the Diver almott cover'd with Water.
To obviate thefe Difficulties of the Diving-Sell, Dr. Bailey, to whom we owe the preceding Account, contriv'd feme further Apparatus, whereby not only to recruit and rcfrefh the Air from Time to Time, but alfo to keej) the Water wholly out of it at any Depth : which he effected after the following Manner :
His Diving-Sell was of Wood about (fo Cubic Feet in its Concavity, coated externally with Lead fo heavy that it would fink empty ; a particular Weight being diflributed about its Bottom, to make it defcend perpendicularly, and no otherwife. In the Top was fix'd a Glafs like a Window, to let in Light from above ; with a Cock, to let out the hot Air : And below, about a Yard under the Sell, was a Stage fufpended from it by three Ropes, each charg'd with an hundred Weight, to keep it fteady.
To fupply Air to this Sell when under Water, he had a couple of Barrels, holding 36 Gallons a-piece, cafed with Lead, fo as to fink empty, each having a Bung-hole at Bottom, to let in the Water as they defcended, and let it out again, as they were drawn up again. In the Top of the Barrels was another Hole, to which was fix'd a leathern Pipe, or Hofe, long enough to hang below the Bung-hole ; being kept down hy a Weight appended. So that the Air driven to the upper Part of the Barrel by the Encroachment of the Water, in the Defcent, could not efcape up this Pipe, unlefs the lower End were lifted up.
_ Thefe Air-Barrels wel'e fitted with Tackle, to make 'em rife and fall alternately, like two Buckets ; being directed in their 3cfcent by Lines faften'd to the under Edge of the Sell : So that they came readily to the Hand of a Man plac'd
on the Stage, to receive 'em ; and who taking up the Ends of the Pipes, affoon as they came above the Surface of the Water in the Barrels, all the Air included in the upperPart thereof was blown forcibly into the Sell; the Water takine its Place. b
One Barrel thus receiv'd, and emptied ; upon a Signal given, it was drawn up, and at the fame time the other let down : By which alternate Succeflion frelh Air was fu'r- nifh'd fo plentifully, that the Learned Doctor himfelf was one of five, who were all together in 9 or 10 Fathoms deep of Water for above an Hour and a half, without the leaf! In- convenience ; the whole Cavity of the Bell being perfeftly
All the Precaution he obferved, was to be let down gra- dually about ii Foot at a Time, and then to flop, and drive
? Ut a. .■ W ^? that had ™ ta ' d fc V takin S in 4 or 5 Barrels of frcjh Air before he defcended further. And being arrived at the Depth intended, he let out as much of the hot Air that had been breath'd, as each Barrel would replenifh with cold, by means of the Cock at the Top of the Bell ; thro' whofe Aperture, tho very final], the Air would rufh with fo much Violence, as to make the Surface of the Sea boil.
Ihus he found, any thing could be done that was requi- red to be done underneath. And by taking off the Stage, he could for a Space as wide as the Circuit of the Bell, lay the Bottom of the Sea fo far dry as not to be over Shoes therein. Befides, that by the Glafs Window fo much Light was tranfmitted, that, when the Sea was clear, and efpecially when the Sun flione, he could fee perfectly well to write, or read, much more to faften, or lay hold of any thing under him that was to be taken up. And by th" Re- turn of the Air Barrels he often fent up Orders written with an Iron Pen on a Plate of Lead, directing how he would be mov'd from Place to Place.
At other times, when the Water was troubled and thick, it would be as dark as Night below ; But in fuch Cafes he was able to keep a Candle burning in the Sell.
The fame Author intimates, that by an additional Con- trivance, he has found it practicable for a Diver to go out of the Sell to a good Diflance from it ; the Air being con- vey d to him in a continued Stream by fmall flexible Pipes, which fcrve him as a Clew to direct him back a" in
- ? „ ' B r e i!- S .° that there feems Jitt) e further wanting to
the Perfection of Diving.
7 e S * e famous Com.Drebell, had an Expedient in fome refpects fupenor even to this; if what is related of it be true. He contrived not only a Veffel to be row'd under Wa- ter, but alfo a Liquor to be carried in the Veffel, which fupplied the Place of frefh Air.
The Veflcl was made for King James I ; carrying 12 Rowers, befide the Paffcngers. It was tried in the River Thames, and one of the Perfons in that fubmarine Navi- gation then living, told it one from whom Mr. Soyle had the Relation.
As to the Liquor, Mr. Soyle affures us, he difcover'd hy a Phyfician who married Drebelfs Daughter, that it was usd from Time to Time, when the Air in the fubmarine Boat was clogg d by the Breath of the Company, and un- vr'% , ^.^fV'^wn : At which Time, by unftopping the Veffel full of this Liquor, he could fpecdily rellore to the troubled Air fuch a Proportion of vital Parrs, as would make it ferve again a good while. The Secret of this Li- quor Drebel would never difclofe to above one Perfon, who himfelt aflured Mr. Soyle what it was. Sovl. ExP Tbyf. Mecb. of the Spring of the Air.
DIVISIBILITY, a paffive Power, or Property in Quantity, whereby it becomes feparable into Parts; either actually, or at leail mentally. See Quantity, and Matter
The School-men define Divifibility, Capaciias Coexten- Jiouis cum pluribus, a Capacity of Coextending with feve- r-all hings : Thus, a Staff 4 Foot long is divifible, becaufe it may be coextended with 4 Feet, or 48 Inches S?c
™f' the Peripateticks, and Cartefiaus, uni vcrf'ally hold an Aftechon, or Property of all Matter, or Body : The Car- tefians, as holding the Effence of Matter to confift in Exten- fion ; For every Part, or Corpufcle of the Body beins ex- r ™™> has Parts withollt Parts, and confequently is divi- fible. See Extension.
The Epicureans, again, hold Divifibility to agree to every Phyhcal Continuum, as, without Parts adjacent to Parts, there can be no Continuity, and wherever there are Parts fo adja- cent, there muft be '-Divifibility. But they deny, that this Affection agrees to all Bodies : For the primary Corpufcles or Atoms they hold perfectly infecable, and indivifible. See Atom.
The principal Argument they alledge, is, that from the Divifibility of all Body, and of every affignable Particle of Body, even after any repeated Number of Di vifions, it follows that the fmalleft Corpufcle is infinitely divifible, which with them is an Abfurdity.For a Body can only bedivjded into fuch Parts as it actually contains. But to fuppofe infinite Parrs T * in
