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sea-going ships, and lie has our best wishes for theirultimate success.
The theory of stability, so important to the navy, andwhich we considered in a geometrical point of view, hasbeen examined, both successfully and ingeniously by theRev. H. Moseley, the President of Jury V.
The stowage of ships has been much improved, of lateyears, both in the form and disposal of stores; thuswater-casks are replaced, at the suggestion of GeneralRentham, by iron tanks. The cubic or prismatic formof these tanks insures a great economy of space as com-pared with the cylindrical form of casks; they also pre-serve the water perfectly pure, during long voyages;casks, on the contrary, have the soluble part of theirwood dissolved by the water, causing putridity, whichproduces various diseases, especially in hot climates.
Equally important with the improvements in keepingwater free from taint, must be considered the inodesinvented by M. Appert for preserving all kinds of meat.
Tiie preservation of gunpowder free from humidity, sonecessary for ships of war, is now rendered perfect bythe employment of hermetically sealed metallic cases, or•wood cases with metallic lining; an improvement due tothe Rritish navy.
In the French navy, great improvements have beenmade by separating passages for the conveyance of car-tridges from the magazine up to the various batteries ofthe ship. These arrangements were particularly re-marked by the English during their visit to the French fleet at Cherbourg in 1850.
We now come to a series of improvements of thehighest importance to tlie safety of ships. The hempcables formerly employed were very objectionable, beingliable to rapid decay, particularly in hot climates. Whenthe anchor was cast on a rocky bottom, the cable wasfrequently cut by the rocks, and very often parted, sothat the ship was greatly endangered.
A captain of the Rritish navy, (Sir Samuel Brown,)introduced cables made of iron links, so arranged as tobe easily worked. These chain-cables are now in generaluse, not only in ships of war, but also in the commercialshipping of every maritime nation. We should havebeen happy if so vast an improvement had been recent ;enough to have received the highest of our awards, asbeing one of the greatest effected for the shipping inte-rests and the preservation of life and property.
The first method for stopping iron cables is due to theEnglish : the last and best belongs to the captain of theFrench frigate “Legotf.” A high encomium is due to M.Barbotin, capitaine de vaiaseau in the French service, forhaving devised the means by which the chain-cable canbe worked on the capstan. The various links as theysucceed each other tall into grooves, on the periphery ofa large polygonal prism forming the body of the capstan,AVhen the capstan is put in motion, the links of thechain-cable have in succession half their thickness lodgedin these grooves, and successively disengage themselveswith mathematical precision.
The improvement in cables naturally leads us to speakof anchors.
Very remarkable improvements have been recentlymade by Lieut . Rodger, R.N., insuring a better distribu-tion of the metal in the direction of the greatest strains.The palm of the anchor, instead of being flat, presentstwo inclined planes, calculated for cutting the saud ormud instead of resisting perpendicularly; and the con-sequence is, that these new anchors hold much better inthe ground. The Committee of Lloyds’, so competentto judge of every contrivance likely to preserve ships,have resolved to allow for the anchors of the ships theyinsure, a sixth less weight, if made according to theplan of Lieut . Rodger, to whom we have siren a PrizeMedal.
Another source of safety, most important to ships, isan efficient application of metallic conductors by whichthey are secured against the destructive element of light-ning. Franklin made the immortal discovery of theidentity of artificial electricity and that from the thunder-cloud, and through the instrumentality of the lightning-rod, devised a happy application of his discovery to the
preservation of buildings and ships in thunder storms.The variable and complicated circumstances, however,under which ships are necessarily placed, rendered the useof such rods on ship-board difficult aud apparently impos-sible. The masts—the only parts to which they couldhe well applied—consist of many distinct portions; theseit is often requisite to move one upon another, and some-times to remove altogether; they are also liable to injuryfrom wind and other forces acting on them. The de-fence of ships from lightning had hence been confided toa small chain or rope of wire temporarily applied alongthe rigging; but which, from the very nature of theease, fails to afford the full amount of security to hederived from a more powerful conductor permanentlyfixed along the mast. Sir W. S. Harris conceived theidea of making capacious metallic conductors an inte-gral part of the masts and hull of the vessel, so as tobring the general fabric into that perfect conducting ornon-resisting state it would assume, in respect of thematter of lightning, supposing the whole mass to be me-tallic throughout; this he has effected by incorporatingwith the masts and hull a series of copper plates, soarranged as to meet all the varying conditions of thespars, and so tied together that an electrical discharge,striking upon any part of the vessel, cannot enter uponany circuit of which the conductors do not form a part,
S and thus the ship is preserved from the effects of light-! ning at all times and under all circumstances, withoutthe officers and crew being in any way concerned in thematter. Sir W. S. Harris has shown, by original re-searches in science, that in whatever position the slidingmasts may be placed, a line or lines of conductors passthrough the ship to the sea, affording less resistance tothe passage of the electrical discharge, than any otherarrangement which can be devised. The most perfectsecurity is derived from the plan thus introduced. SirBaldwin "Walker, one of our fellow jurors, has himselfexperienced the great advantages of this system in alarge frigate commanded by him, which was struck, bothon the fore and main-masts, by heavy discharges oflightning on the coast of Mexico . In this case, theforce of the discharge was such as to partially fuse the me-tallic point aloft on which the lightningstnick, and leavespots of fusion on the surface of the conducting plates,but without the least damage being done to the spars orhull; and this, too, while the top-gallant-masts werehoused.
We have given our highest award to this, which weconsider as the best apparatus for the preservation ofships against the terrible effects of lightning.
Another source of safety in the construction of ships isthe substitution of iron for wood. In a country likeGreat Britain, where iron is so abundant, cheap, and welladapted to various purposes, it was natural to use itinstead of wood for ship-building. Iron ships have thegreat advantage of not being liable to that rapid decayto which wooden ships are subject, especially iu hot cli-mates ; and to the dry-rot which attacks them in moistclimates; iron, likewise, cannot be attacked by theworms so destructive to wood under water. Iron shipscan also be made lighter, with the same hulk, as com-pared with wooden ships; and they resist better in caseof being driven on shore or upon a bank of sand. Suchare the advantages which justify the employment of ironin ship-building. In ships of war, however, the ironsheets of the hull are liable to be rent by cannon-ballsiu such a way as, in many cases, to render it impossibleto stop the leak and save the ship. Maritime countrieshave, therefore, after expensive experiments, abandonedthe idea of wholly substituting iron for wood, in thebuilding of ships of war.
The rigging, blocks, and sails of ships have been im-proved both in their combinations and materials. Theconstruction of blocks is managed with remarkable eco-nomy since the invention of the admirable block ma-chinery by the late Sir J. Isambard Brunei, in his youtha French naval officer. We have awarded Prize Medalsto improvements in the construction of large blockscomposed of several pieces of wood, by which are ob-tained economy in material aud a better fitting of their
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