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DIVIDING EX' 



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DIVIDING KNUINR. 



1>1\I\.; IIK1.L. Mil* inanity ha* 



which reoctvw a oompB*ation from the public 



dorotod from an early 



ptriod to th* ouutrivanoc at apparatus for enahHng men to dire, or 

 dMotod baiMtfc the surface of water, to greater depth, for longer 



of time, and with ! eiarl.on nd danger, than in pomble by the 

 power* of UM body. The fatal oonMauenoe* of continued 

 are deearihed under AiraYXU and DHOWXINO ; and 

 from the hate then Hated it i* evident that about half a minute is 

 period during which most individual* can cafely remain 

 irithout aoroe provition for the supply of air for respira- 

 eoeed divert may remain under water much longer, 

 though not without great and painful exertion ; but the longest period 

 of ubnT.-ii. with a few extraordinary exception*, doai not exceed 

 two minute* ; a apace of time too brief to allow the performance of 

 any but the simple* operation* beneath the mrfaoe of the water. The 

 peari-nabery afford* the moat prominent example of the employment 

 of direr* nniarinted by apparatus for providing a supply of air. The 

 mode of diring adopted, and the effect* of protracted submersion upon 

 the divan, are deaoribed under PEARL FISHERY. Professor Beckmann 

 allndea to the employment of direr* in ancient times to astist in 

 raiting anchor*, in recovering good* from wrecks, or luch an had been 

 thrown overboard in times of danger, and in destroying the works and 

 ship* of the enemy in time of war, as well as in nulling for pearls ; but 

 aome of the statements quoted by him are evidently much exaggerated, 

 as they speak of divers remaining for hours under water. Six minutes 

 ia about the longest time of submersion of which any authentic account 

 has appeared in modern times. [PEARL FISHERY.] 



Dr. Bailey, in a paper printed in No. 849 of the ' Philosophical 

 Tranaaotiona ' (vol. xjtix., p. 492), entitled ' The Art of Living under 

 Water/ observes that the divers for sponges in the Archipelago were 

 accustomed to take down in their mouths a piece of sponge soaked in 

 oil, by which they were enabled to dive for a longer period than with- 

 out it. A the bulk of the sponge must diminish the quantity of air 

 which the diver could contain in his mouth, it does not appear probable 

 that this practice could assist respiration. 



ID connection with diving by the unassisted powers of the body, 

 allusion may be made to a curious and important fact related in the 

 ' Encyclopedia Britannica,' on the authority of Professor Faraday, to 

 whom it was first noticed by a gentleman connected with the Asiatic 

 Society. The lungs ore, in their natural state, charged with a large 

 quantity of impure air ; this being a portion of the carbonic acid gas 

 which is formed during respiration, but which, after each expiration, 

 remain* lodged in the involved passages of the pulmonary vessels. By 

 breathing hard for a short time, as a person does after violent exercise, 

 thin impure air is expelled, and its place is supplied by pure atmo- 

 spheric air, by which a person will be enabled to hold bin breath much 

 longer than without such precaution. The writer states that although 

 he could only hold breath, after breathing in the ordinary way, for 

 about three quarters of a minute, and that with great difficulty, he 

 felt no inconvenience, after making eight or ten forced respirations to 

 clear the lungs, until the mouth and nostrils had been closed more 

 than a minute and a half ; and that he continued to hold breath to 

 the end of the second minute. A knowledge of this fact may in many 

 oases be of great importance, as it may enable a diver to remain -under 

 water at least twice as long as be otherwise could do. It is suggested 

 that possibly the exertion of swimming may have the effect of occa- 

 sioning the lungs to be cleared ; so that persons accustomed to diving 

 may unconsciously avail themselves of this preparatory measure. 



Another important fact, related in the same work, indicates the 

 advantage of breathing condensed air, and thereby obtaining a larger 

 supply of oxygen in the same bulk than with air of the ordinary pres- 

 sure. After one of the disastrous occurrences at the works of the 

 Thames Tunnel, Mr. Brunei, the engineer, descended in a diving-bell 

 to examine the breach made by the irruption of the river into the 

 tunnel. The bell descended to the mouth of the opening, a <1 

 about thirty feet ; but the breach was too narrow to allow it to go 

 lower, in order that the shield and other works, which lay eight or ten 

 feet deeper, might be examined from the bell. Brunei therefore took 

 hold of a rope, and dived below the bell for the purpose. After he 

 bad irmaine<l under water about two minutes, his companion in the 

 bell became alarmed, and gave a signal which occasioned Brunei to 

 rise. On doing so he was surprised to find how much time hod 

 elapsed; and, on repeating the experiment, he ascertained that he 

 could with eaae remain fully two minutes under water ; a circumstance 

 accounted for by the condensation of the air in the bell, from 

 hi* lung* were supplied, l.y the pressure of a column of water nearly 

 thirty feet high, which would condense the air into little more than 

 one half of its usual bulk. 



Many plant were suggested for enabling persons to remain for a 

 longer period under water than is possible by the natural power* >-i the 

 body, long before extensive use wa made of any of them. Beckmatin 

 allude* to a passage of Aristotle (problem xxxii., g 5), which has b. 

 posed to intimate that in his time divers used a kind of kettle t > 

 them to continue longer under water ; but this ]a*agc is v.-i i 

 : 1 by different translators, and Bockmann appears to pla- 



<t,ites that the olden information we have 



respecting UM nt* of the diving-bell in Kurope i* that of John Tawnier, 

 quoted by P. Chupar Sohott It occurs in the ' Technioa Curioaa, aive 

 Mirabilia Artis.' fte., of Sohott, which wai published at Number*, in 

 1W4. lib. vL, cap. ix., p. 393, and i* taken from the ' Opuaculum de 

 ' 'olerrimo ' of Tainnier, who ay, " Were the ignorant vulgar 

 told that one could deaosod to the bottom of the Rhine, in the midst 

 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 water, they 

 would consider it a* altogether ridiculous and impossible. This, how- 

 ever, I taw don* at Toledo in Spain, in the year 1638, before the em- 

 peror Charles V. and almost ten thousand spectator*. The experiment 

 wan made by two Greek*, who, taking a very large kettle suspended by 

 ropes, . with the mouth downwards, fixed beams and planks in the 

 middle of its concavity, upon which they placed themselves, together 

 with a candle. The kettle was equipoised by means of lead fixed 

 round its mouth, so that when let down towards the water no part of 

 its circumference should t'nieh the water sooner than another, eb* the 

 water might easily have overcome the air included in it, and have con- 

 verted it into moist vapour." Schott calls the machine described, 

 " Caoabus aquation*," or an "aquatic kettle ; " but he also describes an 

 apparatus called " Lorica aquatioa," or " aquatic armour," which would 

 enable those who were covered with it to walk under water, and liu-h 

 he seems to prefer to the " cacabus aquaticus'" previously described. t 

 This apparatus is represented in plate 31 of Schotfs work, which 

 shows a man walking into the water with a covering like a small 

 diving-bell over his head, descending nearly to his feet. 



In Kngland, without noticing the supposed contrivance of a diving- 

 machine by Roger Bacon, it is evident that the diving-bell was known 

 at an early period. It is mentioned by Lord Bacon (' Novum Organ urn,' 

 lib. ii. S 50; and ' Phenomena Universi,' p. 702) as a machine used to 

 assist persons labouring under water upon wrecks, by affording a 

 reservoir of air to which they might resort whenever they required to 

 take breath. 



Some curious information on submarine operations is given in the 

 postscript to a little volume published at Kdinlmrgh, in "1688, by ( 

 Sinclar, " sometime Professor of Philosophy in the College of Glasgow," 

 entitle! 'The. Principles of Astronomy and Navigation.' The post- 

 script contains an account of how " to buoy up a ship of any burden, 

 fivm the ground of the sea," and states that among those who 1: 

 this ntion, attempted t to recover property from wrecks by diving, was 

 the late Marquis of Argyle, " who having obtained a patent from the 

 king, of one of the Spanish Armada, which was sunk in the I 

 Mull, anno 1588, employed James Colquhoun, of Glasgow, a man of 

 singular knowledge and skill in all mechanical arts and sciences." 

 " This man," he proceeds, " not knowing the diving-bell, went down 

 several times, the air from above being communicated to his lungs by 

 a long pipe of leather. He only viewed and surveyed the ship. 

 suppose buoyed nothing up." Sinclar subsequently states that about 

 1664, the (then) late Lord Argyle employed an ingenious gentleman, 

 the laird of Melgim, who went down with a diving-bell and got up 

 three guns. A third and more successful trial was made, he says, 

 several years after ; and, still later, one Captain Smith was so con- 

 fident of obtaining the gold supposed to be lost with the ship, that he 

 would ilot admit a co-partner in the enterprise ; which, however, came 

 to nothing. Sinclar proposed to roue wrecks by the buoyancy of arks 

 or boxes, open at the bottom, which were to be sunk full of water, 

 and then filled with air either by sending down casks of air ; by 

 bellows and a long tube ; or otherwise. He alludes to the occasional 

 use of casks for the purpose of raising vessels, and explains win . 

 at a great depth, they are liable to be crushed by the pressure of tin- 

 water, showing that, by allowing the water to enter by a hole in the 

 lower part of the cask, it would so compress the air as to produce 

 an equilibrium of pressure, and thereby preserve it from fracture. 

 About the time that the work above quoted was published, William 

 Phips, who subsequently became governor of New Kngland, attempted 

 to raise treasure from the wreck of a Spanish ship sunk on the coast of 

 Hispaniola. What was the precise character of his apparatus, we are 

 not informed. His earliest experiments failed, but he was so confident 

 of success, that he sought for assistance to enable him to prosecu 

 scheme. He at length obtained the patronage of the Duke ol 

 marie, son of the celebrated Monk, and in 1687, after many difficulties, 

 he succeeded in raising a large quantity of treasure, with whi.'li lie 

 returned to England; where he was honoured with knight h.-. 

 his enterprise. Most accounts state that the property he reo 

 amounted to 200.000/. ; but in the ' Life of Sir William Phips,' pub- 

 lished in. in 1(')97, but attributed to Increase Mather, it is 

 stated as 300,000/. It is unnecessary to cite further instance*. 

 use of diving apparatus, or to notice other early author* who have 

 mentioned the' diving-bell, except to observe that Beckraann alludes 

 to engravings in editions of Vegetius on the art of war, published in 

 1511 and 1532, representing a diver with a eup, from whie-h rises a long 

 leathern pipe, terminating in an opening which floats upon the surface 



* \\ c. quota from the train-Union In the English" edition of Bcckmnn' 

 'History of Inventions," by \\illUin Joknilonc, M-coml ftiiUon, 1614, vol. i., 

 p. 184. 



t Ilinwordi art: "Longe mrlior cut all* ilia, quam ex Francinco Konlero 

 proponit Dani'l Sehrmlma In rirlMI* Mathfiniitici," Port 12, prop. IS. 



