346
[Uniter
Fig. 3. The vane spindle; in which st is the portioninserted into the royal mast; s the thread of a screw forsecuring it; D a thick cylindrical base, with a hole at Dfor a small lever.
Fig. 4. The step of the mast and portion of keelson.A B, M N the transverse and longitudinal branches passinground the step, and through the mortice at S; fc thebranch over keelson; bolts, a be.
[The several nautical and scientific conditions whichthis system of lightning-conductors in ships professes tosatisfy are as follow:—
The conductors are capacious, and always in place,consequently ready to meet the most unexpected danger,at all times and under any circumstances, in which thegeneral fabric in all its casualties may become placed.The system of conductors, whilst being permanently fixedthroughout their whole extent, still admit, upon demon-strable principles, of electrical action, the perfect motionof the sliding masts one on the other, or of any part of themast being removed, either by accident or design, withoutfor an instant interfering with the protecting power. Theconductors are independent of the officers or crew of theship; so that the sailors are never required to handle orreplace them, often a very perilous and annoying service.The conducting plates are quite clear of the standing andrunning rigging: the whole series is calculated to resistexternal violence, and at the same time yield to anyflexure or strain incidental to the spars to which theyare applied. Finally, the whole system is so arranged,that a discharge of lightning falling on any part of theship could scarcely enter upon any circuit in its courseto the sea of which the conductors did not form a part;hence arises that perfect security which experience hasshown to be derived from such a system.
In the original conception of this system, the inventorwas led to consider the electrical discharge, as seen in thephenomenon of lightning, to be an explosive form ofaction of some unknown agency in nature when forcingits way through resisting matter, such as air, all vitreousand resinous bodies, and some other kinds of matter;whilst in traversing other bodies, offering but a very smallresistance to its progress, this explosive form of action wecall lightning becomes transformed into a sort of com-paratively quiescent current. The attempt was, therefore,to bring a ship, as far as possible, into that passive or non-resisting state which she would possess as regards the elec-trical discharge, supposing the entire mass were metallicthroughout, so that, from the instant the agency oflightning struck upon any portion of the masts aloft, theexplosive action would vanish, and the electrical dischargebe prevented from traversing the vessel under the formof lightning. The following extract from the officialjournal of H.M.S. “ Conway,” 28, whilst proving, by agreat natural experiment, in common with numerousother cases, the truth of this deduction, is of no ordinaryinterest in practical science:—
“ Port Louis, Isle of France, 9th March 184G, 11.45 a.m.The pendant staff at main-top mast-head was shivered inpieces by lightning, Harris’s conductor carrying off thefluid without further damage.”
The ship was refitting at this time, and the top-gallantmasts on deck, so that a small spar was set up at the top-mast head as a temporary support for the pendant; thisspar had not, consequently, any conductor on it. It isseen by the ship’s journal that the spar was shivered inpieces by the explosive action, which became immediatelytransformed into a comparatively quiescent current onreaching the line of conduction.
The report of the thunder was as if one of the main-
deck guns had been fired. The gunner, who was sitting R 1his berth, immediately under one of the lateral branchesof the conductor passing through the ship, saw, throughthe scuttle port, a brilliant blaze of light from the shipupon the sea, but experienced no inconvenience.]
151 Husband, J., Mylor, Falmouth —Inventor andConstructor.
Model of a new life-boat.
Frame of a merchant ship, showing a plan of securingheads and heels of timbers, without chocks or dowells.
152 Aldebert, I., 57 Long Acre —Inventor.
Model of a first-class frigate.
153 Turnbull, Robert, South Shields —Designer.Model of the hull of a merchant ship, of 867 tons O.
built according to Lloyd’s rules, on a scale of a quarter oIan inch to the foot.
154 Turnbull, Edwin, Whitby, Yorkshire —Manufacturer,
Models of a 74-gun ship, of the time of Lord Nelson )and of the steam-ship “ Phcenix.”
156 Hall, James, Bromley , Bow, Middlesex —
Proprietor. .
Models of ships’ rudders, and a plan for wearing a shTwithout a rudder.
157 Bell, Hugh, Baltic Wharf ., Millbank — Inventor
and Manufacturer. .
Life-boat, for the beach, on the scale of 1 inch to tnfoot. One end of the boat. The lines representingmanner in which the two layers of planks should croseach other, and the keel and keelson in single pla 11 *from gunwale to gunwale. It is intended that th ershould be a waterproof elastic material between y*layers of planks, to prevent escapage, and to dimi nlSthe effect of concussion.
Gutta-percha canister fitted into the boat. CopP ecanister, which may fit the same end of the boat.to bale out the water after the plug-holes are st°pp c ^Cradle for transmitting every kind of boat from placeplace on land. A set of boats in the position of a shJP glong boat, intended for emigrant passenger, troop ship tand men-of-war.
158 Browne, Wm. Cheselden, Totness , Devonshire —'
Inventor. > i e
Model of “ The Princess Royal,” 120-gun ship, h 1of wood and card-board.
159 Harvey, D,, 3 Gumming Place , PentonviUe Hill —
Inventor. < . n d
Model of Her Majesty’s royal yacht “ The VictoriaAlbert,” on a scale of one-eighth of an inch to the 1°and of “ The Fairy,” screw yacht , on a scale of 0eighth of an inch to the foot. A tender to the s£l nAlso of a 46-gun frigate, on a scale of three-eighths o ^inch to the foot. It is not modelled in the usualis practically built, with frame timbers, and planked ° , oJJhaving one plank streak left out, to show the dispelof the timbers.
160 Gray, John, Newhaven , Sussex —Ship-builder• ^
A mechanical model of a South Sea whale fishery
on a scale of a quarter of an inch to the foot, with a ,t e d,lengths of timbers, planks, &c., properly shifted, & ^ land fastened as required by Lloyd’s rules to Class j e ],in the registry; as also in every other part of the §\\as far as it is completed. There are in theseparate timbers, 19 lower and 22 upper deck1,844 treenails, 4,710 bolts.
161 Horn, Henry, Victoria Cottage, Kingston , Portse
—Manufacturer and Designer. . s cal eModel of a 12-gun brig, on a slip for launching?a quarter of an inch to a foot.