Friar Bacon was the first Englishman to suggest appliances of a scientific nature to aid in submarine explorations. In his Discoveries of the Miracles of Art, Nature, and Magic (circa A.D. 1252), Chapter IV., "of admirable artificial instruments," he says, "a man may make an engine whereby, without any corporal danger, he may walk at the bottom of the sea or other waters;" but he does not enter into details upon the project, and for three centuries no action was taken upon the hint he threw out. From the sixteenth century to the present time, however, the ingenuity of inventors has been applied to the object of overcoming the difficulties of carrying on useful submarine operations, and their projects seem to have divided themselves into three classes: namely, diving-vessels to be navigated under water with the same facility as on the surface, the divingbell, and the modern diving-dress. Notwithstanding the patient efforts of inventors, the first class may be declared, up to the present time, practical failures, while the other two are engaged in active work, and enter much more largely into all the purposes of modern enterprise than the generality of people are apt to suppose.

In the reign of James I., one Cornelius Debrell planned a vessel which should carry twelve rowers besides passengers, and which should be navigated under water, with the idea which has prompted this sort of invention throughout, of operating without being observed upon the ships of the enemy in time of war. We cannot make out whether the experiment was carried into effect or not. One account is, however, circumstantial in the affirmative, as it purports to be the relation of one of the men who rowed the boat when it was tried in the Thames. Debrell pretended to have discovered a subtle liquor, the distillation of which from a bottle enabled him to correct the impurities of the air already breathed by the rowers, and to render it fit again for respiration. This invention he kept secret. It was, however, said to have been discovered by Boyle, who obtained his information from the physician who married Debrell's daughter; but at any rate the mystery of manufacturing this wondrous elixir vitæ passed away with Boyle and the physician, and no one has happened upon it since. Attempts were subsequently made on behalf of the Landgrave of Hesse to accomplish the same object. The model selected was Debrell's vessel, which was a wooden tub of an elliptical shape, six feet high, and supplied with air by pipes communicating with the surface. The descent and ascent of the vessel were regulated by means of a compartment into which water was introduced when it was desired to go down, and from which it was expelled when an ascent was to be made. It was constructed to contain over a hundred cubic feet of air, and upon a calculation that as thirty-two cubic feet would last a diver an hour, four persons could remain in the vessel for that period without the necessity of drawing air from above. A full description of this vessel will be found in the Gentleman's Magazine for December, 1747. In the same Magazine for 1749, mention is made of a vessel constructed by one Symons, in 1729. It appears to have been made of a size to contain

sufficient air to last one man three-quarters of an hour, was water-tight, and was made to sink by a certain calculated weight of lead. Symons himself sunk the boat to the bottom of the Dart, and remained there for nearly an hour; but the vessel of course was a simple curiosity without practical qualities. Symons complains that on the occasion of exhibiting his vessel in the Dart, he only received five shillings, although there was a large number of persons present. In 1774 a check was put upon this description of experiment by the fate of John Day. He appears to have so far improved upon Symons's model that he actually is said to have sunk himself in thirty feet of water in a pool near Norwich, and to have remained there for twenty-four hours. His only plan of turning this to account was by getting large bets made that he would not sink a ship a hundred yards deep in the sea (a thing of course out of the question, as the pressure of the water at that depth would have burst in the sides) and remain there for twenty-four hours. The Sporting Kalendar was examined, and a Mr. Blake fixed upon as the gentleman who should get the bets on. He took the matter up, and large wagers were laid that a vessel which should remain in a hundred feet, not yards, for twenty-four hours, would not be produced in three months. Day was not ready with his vessel in time, and Mr. Blake lost the bets, although he did not lose confidence in Day. For Mr. Blake's satisfaction, the vessel was completed: Day was closed up tightly therein and provided with a watch, a taper, some biscuits, and a bottle of water, with which he was to remain twenty-four hours at the bottom. The experiment took place in Plymouth Sound, in twenty-two fathoms of water. Poor Day went down, but neither he nor his vessel was ever more heard of, in spite of every exertion that was made for his recovery. It is supposed that the man, having no practical knowledge of the pressure of water at that depth, had not made his vessel strong enough, and that as soon as it got to the bottom it cracked up like an eggshell, especially as some ripples were seen to rise on the surface just after he went down. How he proposed to obtain the means of respiration we have not discovered, and we should be slightly inclined to doubt the truth of the alleged rehearsal near Norwich.

In 1787, a Mr. Bushnell, of Connecticut, is said to have constructed a vessel which could be moved under water, and by means of which a magazine of powder could be placed at the bottom of a ship and fired. We have no record of the result of this; but Citizen St. Aubin, a Paris man of letters and a member of the tribunate, gave an account, in 1802, of the bateau plongeur of Mr. Fulton, also an American. Experiments were made with this vessel, in which a compartment to contain sufficient air for eight men during eight hours was contrived, in the harbours of Havre and Brest. The compass points were proved under water, and the boat made way to the extent of half a league. Above all, Fulton added to his boat a machine by means of which he actually did blow up a large boat in Brest Harbour. Attempts have been made in this direction of late years both by Mr. Scott Russell and Mr. W. E. Newton. It is not so long since that the Nautilus-de

signed by Mr. Scott Russell for submarine navigation, and specially intended by him for operations against the Russian ships in the time of the Crimean war-lay high and dry in the yard at Millwall. We believe it had actually been accepted for service by the Admiralty, but the end of the war came before the vessel could prove its utility; and, perhaps we should say happily, it has remained since without employment. The principle of the vessel with respect to its rising and sinking was similar to that we have pointed out in the case of Debrell's ship. When it was intended to sink, certain compartments were filled with water, which was expelled when the voyagers wished to rise. The air supply was drawn through a pipe, the top or funnel of which floated on the water, a device which resembles that mentioned by Pliny and the annotator of Vegetius, and was actually adopted at the end of the last century by Kleingert of Breslau. The Nautilus was fitted with compasses and the other scientific appliances of navigation, and she was rowed from outside by men in diving dresses, who were supplied with air from the inside of the vessel. The great danger of course was of accident to the floating funnel. Experiments were made in Portsmouth Harbour which proved that the vessel could be employed in placing torpedoes underneath ships. In 1857, Mr. W. E. Newton, of London, made some experiments with a vessel which, upon the old model of such ships, was to contain a supply of air sufficient to last a certain number of men a certain time; but we have not heard that Mr. Newton has carried his plans to the point of success; and the same remark applies to the design of Dr. Payerne, mentioned in the catalogue of the Paris Exhibition of 1855, for constructing a submarine vessel with a chemical contrivance for manufacturing fresh air out of the original air supply of the vessel when it becomes vitiated. If this could be accomplished, the grand difficulty of all such schemes would be obviated; but the account we read of Dr. Payerne's proposals did not imbue us with a very sanguine idea of their practicability.

The learned, ingenious, and eccentric Bishop Wilkins has allowed his fancy to run wild about submarine navigation. His reflections upon the subject, suggested by the before-mentioned vessel of Debrell, will be found in his Mathematical Magic. He has imagined a ship which he calls Wilkins' Mercury, or the Secret Swift Messenger, and which, according to his view, could do all manner of things possible and impossible. Upon this matter the learned bishop seems to have been imbued with the true spirit of a Lagado projector. He is rather cloudy in his notions as to the manner of supplying the vessel with air, but evidently relies upon Debrell's quintessence for purifying and renewing the vitiated atmosphere; although he has no idea whatever of how the "quintessence" was composed or how it was to be obtained. He makes one exceedingly funny suggestion for lighting his submarine vessels. Their lamps are to be fed with oil extracted from fish caught by the submarine travellers en route. This is of a piece with the remainder of his speculations, which are thus summed up: Șuch a vossel, he says, would ensure privacy. A man might go to any

coast of the world, invisibly, without being discovered or prevented in his journey. The vessel would be safe from the uncertainty of tides and the violence of tempests, which never affect the sea above five or six paces deep; from pirates, ice, frosts, &c.; it would blow up enemies' ships, would convey supplies secretly to any besieged place, and could be extensively employed in submarine experiments and discoveries. The bishop supposed that the voyagers could obtain supplies of water from fresh springs which they would discover at the bottom of the sea. All kinds of arts could be carried on in such a vessel; learned observations could be made and printed therein. Several colonies might thus inhabit, having their children who could not choose but to be amazed upon the discovery of the upper world. So we should think. The bishop has allowed his hobby to run riot, but the visionary nature of his speculations accords well with the abortive efforts which have been made to carry out such projects.

It is pleasant to turn from this purely speculative aspect of submarine experiment to those in which we may contemplate its services to commerce and to mankind. Practically the art is of too recent a date in its safe and perfect form for it to have rendered much aid to scientific investigation and discovery; but that it will soon render valuable assistance in this direction, there is no doubt whatever. The diving-bell was the first perfected form of diving apparatus, but its history has been so often written, and its method of working is so well known through the Polytechnic lectures and experi ments, that it is unnecessary for us to enter into any common details here. The saying of there being in things evil a soul of goodness, was never more signally exemplified than in the case of Philip's Armada. With its political effects upon this country the students of history will be familiar: but it is at least singular that the richly freighted Spanish galleons which were sunk near our coasts during the storm which destroyed the Armada should have given an impetus to diving operations which has eten yet not ceased to operate. The dreams of divers for the last three centuries have been of the Spanish doubloons which pave the sea bottom in many parts of our coasts. Within the present century large sums of Spanish money have been recovered, and every diver has his pet scheme for making further investigations which may lead him on to fortune and affluence. As early as 1588 the Marquis of Argyll obtained a royal patent, entitling him to all the treasure he could recover from the Spanish ships sunk off the Isle of Mull. For this purpose he employed James Colquhon, of Glasgow, who went down and examined the ships, air being supplied to him by a leathern pipe; but nothing was recovered. Nearly eighty years afterwards, men's minds having been much excited in the meantime, the then Duke of Argyll, in whom the original patent was vested, renewed the operations, which were facilitated by a rude kind of diving-bell on the principle to be found in the scientific apparatus of the present day. After a great deal of trouble, however, only three guns about eight feet long and eight inches in diameter were recovered, and the attempt was again abandoned. The Spanish gold at the bottom of the sea off the Mull

coast had, however, set in motion the spirit of invention which has carried its results forward to the present condition of the diving art. Diving has its romance as well as other departments of human effort. In 1680, nearly a century after the patent of the Marquis of Argyll, one William Phipps, having contrived a square iron box, open at the bottom, with windows and an inside seat for the divers (which is precisely the present arrangement, except that the air is now continually renewed from above, whereas in this machine the stay was limited by the supply of air in the bell), persuaded Charles II. to fit out a ship to enable him to recover some Spanish treasure sunk off Hispaniola. Spanish gold again! His first attempt was a failure, but in 1687, assisted with funds by Monk, Duke of Albemarle, Phipps succeeded in recovering 200,000l. from the wrecks. On his return he was knighted, and from this persevering diver have descended the Mulgraves of diplomatic history. In 1683 great assistance was rendered to those who were engaged in attempting to overcome the practical difficulties of diving by the speculations of George Sinclair, a learned mathematician of Edinburgh. In his Hydrostatica, or Natural Philosophy improved by Experiments, he published a series of calculations which were intended to check rash and unsafe experiments. He showed how the depth to which a vessel of a certain strength could descend was limited by the pressure of the water, and also established a rule for estimating the size of a bell to contain a certain quantity of air for a given number of men to remain in a certain time. If some of the foolish men who lost their lives subsequently had consulted Sinclair, they might have spared themselves the catastrophe. The difficulty of renewing the supply of air was overcome in 1715 by Halley the astronomer. He had an escape-cock fitted to the top of the bell, and had a service of barrels which were sent down to the bottom full of air. These were emptied into the bell, and a continuous air-supply secured. In 1788 Mr. Spalding of Edinburgh, who had made some improvements upon the mechanical arrangement of Halley's bell, but had retained the barrel air-service, engaged to recover some of the cargo of an East Indiaman which had been sunk off the Kish Bank, Ireland. He and his assistant went down, and after the first supply of air was supposed to have been exhausted, the barrels were sent down as usual. No signal having been given for some time, the bell was drawn up, and Mr. Spalding and his assistant were found to be dead. It is supposed that by some means they failed to discharge the air from the barrels into the bell, and were consequently suffocated. The barrel service was always more or less dangerous from its liability to get out of gear; and if Spalding had but adopted the invention of Smeaton, the engineer of the Eddystone Lighthouse, he would in all probability not have lost his life in the manner he did. In 1779 Smeaton applied the pneumatic forcing-pump to the diving-bell. The air was by this machine communicated to the bell from the deck of the ship-the apparatus being connected with the bell by a flexible tube, kept open against the pressure of the water by a spiral brass wire running from end to end. This