Page:Encyclopædia Britannica, Ninth Edition, v. 7.djvu/315

297 DIVING 297 Simons of Renfrew for the River Clyde, which ?. T as com municated by Mr Deas, the engineer, to the Clyde Trustees. Fig. 4 is a longitudinal section, and fig. 5 a plan in which a is the bell, b the bell crab, c the air-pumps, and d the crane for lifting stones, &c., slung by the divers. The large cost of a diving bell limits its use to works of magnitude, especially as many submarine works can be done better by the diving dress, which is much less expensive; but there are certain operations, such as the clearing and levelling of foundations, for which the bell is peculiarly well adapted, that still enable it to take its place as one of the most useful appli ances of the marine engineer. Mr B. B. Stoney has, in an interesting paper in the Mimites of Proceedings of the Institution of Civil Engineers?- described a diving bell, or chamber, 20 feet square, with which he success fully built the foundation of the quays of Dublin. Mr Stoney s apparatus does not come under the article diving, but belongs more properly to the subject of the compressed air cylinders used in bridge building, which are described under the article BRIDGE. Diving Dress. The diving dress is peculiarly well fitted for such works as the repair or overhaul of rollers and sluices of lock-gates, cleaning or repairing ships bottoms, descend ing into the hatches of wrecks to recover property, and, in short, everything that cannot be done from the interior of a bell. The inexpensiveness also of the diving dress, dispensing with all costly staging, and its ease of transport and appliance, are much in favour of its use. It is, indeed, so convenient in the repair of propellers, examining ships bottoms, recovering anchors, &c., that all ships in Her Majesty s navy of sufficient size to be commanded by captains are now supplied with a diving dress or apparatus, and bear a certain number of divers in their complements ; and all sea-going flagships and iron clads on foreign stations carry two sets of diving apparatus, and are allowed a suitable number of trained divers. The invention of the diving dress, like that of most use ful appliances, was gradual, and the work of many minds. Some early proposals, such as that already referred to in the quotation from Dr Halley s paper in 1721, and others of more modern date, were made for providing the diver with a dress to enable him with safety to carry on his work, for an account of which the reader is referred co a paper by Mr J. &quot;W. Heinke in the Minutes of Proceedings of the Institution of Civil Engineers? But to Mr A. Siebe is due the credit of being the first to introduce a dress which was supplied with a constant stream of fresh air, and may bo said to have been the precursor of the dress now in use. We allude to what was called the &quot; open dress &quot; invented in 1829, which consisted of a helmet and water proof jacket, under which, and fitting more closely to the body, were worn trousers reaching to the arm-pits, and between the jacket and trousers the air pumped in at the helmet was allowed to force its way and escape to the surface as in the diving bell, and henc-e it was called &quot; open.&quot; Although some divers of the old school are said still to give a preference to the open dress, its danger became manifest ; for if a diver stumbled and fell on his face or side, the water entered his dress, and unless quickly brought to the surface he was in danger of being drowned a necessary requirement of the open dress being that he should remain in an upright or gently stooping posi tion. To meet this defect, Mr Siebe, in 1837, introduced the &quot; close &quot; dress, which is now almost universally used. Various minor improvements were introduced between 1839 and 1843 connected with the removal of the wreck of the &quot;Royal George&quot; ship of war, conducted by the 1 Vol. xxxvii. p. 339. 1 Vol. xv. p. 309. late Sir Charles Pasley, which will be found fully described in the Minutes of Proceedings of the Institution of Civil Engineers? The long continued experience gained in diving while these operations were in progress suggested improvements and alterations which had a great effect in, bringing the diving dresss to its present perfection as now manufactured by Siebe, Heinke, Barnett, and other makers. The diving dress, as will be understoood from fig. G, envelops the whole body of the diver, the upper por tion a being the &quot; helmet,&quot; the intermediate portion b the &quot; breast-plate,&quot; and the lower portion c the &quot;dress.&quot; The hose by which the air is supplied is shown at d, and e is the &quot; life&quot; or &quot; sig nal&quot; line, which is attached to the diver s waist, and by which he makes signals and is hauled to the surface. The water-proof material of which the dress is made is very generally sheet india- rubber covered on both sides with tanned twill to protect the india rubber from injury. The cuffs fit tightly round the wrists, leaving the hands free, and india-rubber bands slipped over them render the joint water-tight. The breast plate b is made of tinned copper with an outer edge of brass, which has screws Fia ^.-Diving Dress, fitted to it projecting upwards and passing through cor responding holes in the collar of the dress. On the top of this, and with holes in it corresponding to the screws, four pieces of a metal band are firmly screwed clown by wing nuts, nipping the soft material of the collar between the metal of the breast-plate and band, and thus ensuring a water-tight joint. On the front of the breast plate two studs are fastened for securing the back and front weights &amp;lt;j. Some makers put a valve h on the front of the breast-plate, by means of which the diver can regulate the pressure inside his dress at will, and in this way has the power, by simply inflating his dress more or less, of making himself of any specific gravity, so as to float at any desired depth or rise to the surface without the assistance of the attendant. This arrangement in the hands of a skilled diver is undoubtedly a great convenience. But it is still a matter of difference of opinion whether it is not safer to trust to being hauled up by the watchman on the surface, whose duty it is to hold the life or signal line in one hand, and the air hose in the other, while the diver is at work, and to attend to whatever signal he may give by pulling the life line. The inconvenience of the air bubbling up in front of the bulls eyes, and the danger of inexperienced divers becoming giddy and turning the valve the wrong way, have induced some makers to do away with this use ful valve, and to substitute at the back of the helmet a valve which the diver can regulate by the pressure of his hand, but which rights itself the moment his hand is removed. The neck of the breast-plate is fitted with a &quot; segmental screw bayonet joint &quot; (introduced by Messrs Siebe), and to this the helmet, the neck of which is fitted 3 Vol. xv. p. 328. VII. 38