SUBMARINE PHOTOGRAPHY AND SUNKEN VESSELS.

Otago Witness, Issue 787, 28 December 1866, Page 7

SUBMARINE PHOTOGRAPHY AND SUNKEN VESSELS.

(From the" Mechanics' Magazine.)

It is 'eldora that the scientific enterprises and mechanical inventions of private individuals are favored with the presence of royalty, and still less seldom do they receive its sanction and encouragement. In our own country nobody would expect such a thing; a fair trial from those in authority is all that any sane inventor would dream of, and it would be a miracle if it turned out anything else but a dream. Fortunately for French engineers " they manage these things better in France;" and a proof has lately been afforded by a visit paid by the Emperor and Empress to witness some very valuable and interesting experiments conducted under the superintendence of M. Bazin. It appears, on the authority of "Le Genie Industriel," that for the last twelve or fi' teen years this gentleman has been actively and unremittingly engaged in bring ing to maturity a variety of mechanical inventions. The question of electrical illumination has occupied a considerable share of his attention: and he has recently succeeded in applying it for the purpose of illuminating the bottom of the sea and deep rivers, with the object of taking accurate soundings, and also of discovering the exact localities and position of sunken vessels. In order to effect his preliminary reconnaisauce, M. Bazin descends in what he terms his "photographic chamber." The greatest depth hitherto ventured upon averages from 230 ft. to 270 ft., and he remains there for the space of about ten or eleven minutes, quite a sufficient space of time to enable him to take a photograph of the whole area embraced by the rays of the electric light. The chamber is simply a box constructed of strong sheet iron, braced with transverse Btiffeners on all Bides, and in which the occupant remains absolutely hermetically closed up. Thick, lensshaped glass windows afford every facility for discovering whatever is lying ptrdu. in the depths below, and at the same time obviate all ri6k of giving way under the pressure of the circumambient fluid. The photographic views exhibited by M. Bazin have proved thoroughly satisfactory in respect to clearness of outline and accuracy of definition, thus affording all the data necessary for successfully undertaking the raising of the objects whose situation has been previously ascertained. - The principal distinction between the

chamber of our inventor and tbe ordinary diving bell is, that in the latter a constant supply of fresh air is kept up by the aid of pumps to replace the vitiated air, which escapes through a valve for that purpose ; while, in the former, there is no such renewed supply. It contains simply a quantity of air answering to its own capacity ; consequently when this amount become 8 inhaled and exhaled it is no longer fit for tbe purposes of respiration. The inventor,, aware tbat it would be impossible to attain complete safety by the process oi supplying air at the great depths he contemplates descending to, prefers attaining his object by his own apparatus, which is sufficiently large and commodious to contain two person and the instruments necessary to accomplish the operations to be carried out. There is no doubt that JVL Bazin's chamber has the merit of perfectly preventing the " entrance of water, but ifc is palpable tbat the communication with the upper regions must be regular and constant to ensure the hauling up of the apparatus at the proper time, or the chances are tbat its occupants would be asphyxiated. In fact, this unpleasant contingency of suffocation very nearly happened to the inventor himself during one of his "first experiments, ia 1865, at Cherbourg. Having shut himself ; up in his hermetically-sealed chamber, the signal was given to lower away, and M. Bazin descended to a depth of nearly 20Oft. in the water. Having completed his observations, and exhausted, so tospeak, all the air in the chamber, he gave the signal to be hauled up. To his inexpressible alarm and astonishment it was not responded to; he tried a Hecond and a third time ; still no answer. The blood now commenced to surge rapidly towards his head, his vision became obscured, and his breathing heavy and obstructed. It was not until he had remained seven minutes — to one in his position an eternity — beyond the proper time that he was brought to the surface, more dead than alive.

The mere submarine examination of sunken vessels comprises but a smill portion of the task to be accomplished. The more important step is to raise them. Ever since the Crimean War a variety of ingenious inventions have been put forward from time to time, and many of there tested practically. None of them, however, can be said to have been successful in the full sense of the term. One of the difficulties attending the employment of the ordinary methods is that divers are compelled to go down underthe water to attach the grappling irons and chains required to lift thevessel. With the object of surmounting these difficulties our inventor has designed a machine in the shape of an immense iron net, hung round with a great number of leaden weights. This huge net is suspended by means of chains and gearing, supported by boats moored in the vicinity, above the site of the sufiken vessel, and gradually lowered until it completely covers it. Directly the leaden weights touch the bottom the hauling up is commenced ; as the net tightens the meshes approach one another, and the vessel is embraced on all sides, as if by a multitude of vices, and it is manifest that so long as the net holds good the vessels must must come up. From the manner in which the machine i& constructed it is quite impossible that any slipping or sliding of the parts in contact with the sides of the vessel can take place. The vessel must either come to the surface or the net break ; it is a simple question of power and resistance. By means of his apparatus M. Bazin raised a sunken vessel in the presence of their Majesties the Emperor and Empress of the French, and was warmly congratulated by them on the great buccess which attended the application of his invention. It would be wortb while for those who are interested ia the raising of the ill- starred London to consider whether these means are at their disposal for effecting their purpose, especially as all attempts to recover the ship have hitherto proved abortive.

Great Britain, says an American paper. pays annually 1,000,000 dollars for dried carcases of that tiny insect known as thecochineal; while another — also peculiar to India— gum shellac, or, rather its production, is scarcely less valuable. More than 1.500,000 human beings derive their sole support from the culture and manufacture of the fibres spun by the silkworm, of which the annual circulating medium is said to be 200,000,000 dollars. In England alone — to say nothing of the other parts of Europe— soo,ooo dollars are spent every year in the purchase ef foreign honey, while the value of that which is native is not mentioned, and all that is the work of the bee ; but this makes no mention of 10,000lbs of wax imported every year. Besides all this there are the gall nuts, used for dyeing and making ink ; the cantbarides, or Spanish fly, used in medicine. In fact, every insect is contributing in some way, directly or indirectly, in swelling the amount of our commercial profits.