www.e-rara.ch The principles and practice and explanation... The principles and practice and explanation of the machinery used in steam navigation - examples of British and American steam vessels; and papers on the properties of steam and on the steam engine in its general application / amended in this edition: with the addition of recent examples of the ... Tredgold, Thomas London, MDCCCLI. [1851] ETH-Bibliothek Zürich Shelf Mark: Rar 29166: 2 Persistent Link: http://dx.doi.org/10.3931/e-rara-71316 Steam navigation. Fourth paper. www.e-rara.ch Die Plattform e-rara.ch macht die in Schweizer Bibliotheken vorhandenen Drucke online verfügbar. Das Spektrum reicht von Büchern über Karten bis zu illustrierten Materialien – von den Anfängen des Buchdrucks bis ins 20. Jahrhundert. e-rara.ch provides online access to rare books available in Swiss libraries. 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Having been enabled to lay before our readers a set of plan drawings of the splendid steam ship of war ‘ Medea/ we annex a brief memoir of facts connected with that vessel, and her performance under a variety of circumstances, which may become interesting to those who take into consideration the extraordinary revolution which the steam engine is accomplishing in nautical affairs; not only in abridging time and space, and thus bringing distant nations into close communion with each other, but in its scarcely less important application, when allied to our fleets as a powerful auxiliary in war: and although the philanthropist will not view these consequences with the same complacency that attends the contemplation of the benefits which the agency of steam confers upon mankind, yet this subject maybe favourably considered, under the conviction that the most effectual way of preserving peace is to be prepared at all times for war. The change, therefore, which the steam engine must effect, in the tactics of naval warfare, cannot be viewed with indifference in a country whose “ best bulwarks are her wooden walls.” Previous to the year 1830, the Government possessed only a few small steamers, which were principally employed for the purpose of towing ships in and out of harbour, and other trifling services on the coast, with an occasional voyage to Lisbon or Gibraltar. These vessels were built very strong ; and although it became necessary in the first instance to employ them in the conveyance of the Mediterranean mails, on the adoption of steamers for that service they were removed to other duty as soon as more competent vessels could be built expressly as packets. About the year before mentioned, the Admiralty, having judiciously determined to add a small squadron of steam cruizers to the Navy, gave directions for the construction of a steam ship of war at each of the Royal Dockyards,—the form, scantling, and internal arrangements being left in a great measure to the judgment and skill of the master shipwright of the yard a 2 STEAM NAVIGATION. at which each vessel was designed and built ; well considering, that although many private steamers then existed, even of the size suitable for war purposes,—which vessels, from the excellence of their performance, appeared to realize the perfection of what we may call the art of steam navigation in its then state of advancement,—yet that the necessary qualifications for an armed ship of any sort, particularly for distant cruizing and extended voyages, with a powerful armament and large crew, differed so essentially from those of a merchant vessel, as to render it extremely dangerous to follow without variation even the most approved plan of any commercial steamers, whose sole object was the conveyance of passengers and cargo on coasting voyages, never at that time extending beyond four or five hundred miles, and throughout the whole of which route, they generally had some port of refuge, to which they might have recourse, either in extremely bad weather, or for a supply of fuel if necessary. In carrying into effect this plan of building a few war steamers, it became important that they should be so constructed as to be able to cruize and make long passages under sail alone; it being obvious that if a war steamer is to be dependent on the power of her engines for every movement, she will in all probability exhaust her resources before arrival at her scene of action. To accomplish this end, therefore, became of vital importance, and it was considered unavailing for them to possess good steaming qualities unless they were in all respects quite competent to act as sailing ships of war. Although it is unnecessary to state here all the particulars in which the construction of ships of war differs from that of merchant vessels, there are some important features which so much affect steamers, and have so great an influence on their character as such for velocity, when competing with passenger vessels or packets, that we deem it necessary to advert to them here. The war steamers being armed with the heaviest description of guns, one of which, weighing together with its carriage more than six tons, is placed at each extremity of the vessel, with others of somewhat less weight on the sides, it becomes necessary to afford the proper support, not only when steaming in an upright position, with the centre of gravity of the displacement in the plane of the keel, but perhaps engaging, when under sail, with a considerable inclination, and the whole weight of ordnance probably on the lee or depressed side. It is necessary, we say, from these considerations, and others connected with the ponderous appurtenances of war ships, among which may also be named the additional number and weight of the anchors, which are always carried on the ship’s side, that all the superstructure, or the whole fabric above the water, should be very much stronger, and therefore heavier, than is required in any steam vessel carrying passengers, or even a heavy description of cargo, which, being always stowed below, admits of the upper works being slight. It is also indispensable that the war vessel should have a high and strong bulwark or ‘ berthing,’ to afford shelter to the crew in time of action; and, above all, it is necessary that the form of the ship should vary considerably from that most calculated to insure velocity, when, as in the case of steamers, it is derived from a self-contained motor, instead of being dependent on the influence of the wind, on sails attached to the lofty and weighty masts, &c. of a sailing vessel, the oblique action of which in most instances tends as much to depress the ship as to propel her on the line of keel. Thus, any vessel intended to act either as a sailing ship or steamer, must, to insure her HER MAJESTY’S STEAM SHIP THE ' MEDEA .’ 3 being a good sea-boat, have greater stability, and more breadth of beam, than is required for one dependent entirely upon the engines. It is scarcely necessary to add the conclusions to which this argument leads, or to state that these important essentials must considerably diminish the steaming speed of a war steamer. We should not have thought it requisite here to refer to these peculiarities of construction, were it not for the many aspersions which have been cast upon what we may presume to call the architectural qualities of the Government steam marine, by those who apparently have never taken into account the matter to which we have alluded, and who have generally been in the habit of estimating the qualities of steamers entirely from the rate at which they would, in an upright position, be propelled by the engines,—omitting in a great degree the consideration, that the sharp narrow vessels in which the greatest steaming speed is obtained, are not well adapted for general ocean navigation, and that although they may succeed for a long time in making favourable passages, they must, in the event of any failure of the engine, or the supply of coals in a gale of wind, become unmanageable logs on the water.