TRANSACT10^fS OP THE SECTIONS. 257 



A Proposal for a Class of Gunboats mpahle of enrfaijhif/ Armour-plated Ships 

 at Sea, accompanied with Suggestions for fastenimj on Armour-Plates. By 

 Dr. Ebdy. 



The author thought that the monster iron-clad vessels which we and our neigh- 

 bours were building might be successfully assailed by vessels of very inferior size 

 specially designed for the purpose. The first essential condition for such vessels 

 was superiority of speed, with such protection as to approach the enemy without 

 being crippled. He believed that one such vessel with a couple of heavy guns 

 might so harass a larger vessel as to paralyze her movements, and that two such 

 vessels might even engage -with advantage ; and, if this was so, might not a flotilla 

 of these smaU vessels advantageously engage a fleet of the large iron-plated ships ? 

 To obtain superior speed, we must either sacrifice weight of metal or increase the 

 size. He preferred the former, and by reducing the armament to a very few guna 

 (two or four), and those of the powerful kind now manuftictured, he thought we 

 might obtain the required speed within moderate dimensions ; and he hoped to 

 show that, by a peculiar adjustment of material, we might gain all the protection 

 required, without immoderate weight. Much of this problem had indeed been 

 worked out by Capt. Coles, of whose cupola, the conical fort, with revolving 

 shield, in the moclel produced, was a modification. A speed of sixteen knots 

 an hour woidd, he believed, be sufficient for present piu-poses, and he took it that 

 this speed might be secured without difficidty in a vessel of fine lines, and of cer- 

 tain proportions, without tremendous size. Dr. Eddy proceeded to describe from 

 a model the kind of gimboat he proposed to build. The dimensions, he said, were 

 calculated from one datum, namely, the least elevation above water at which the 

 guns coidd advantageously be laid, which he took to be 8 feet. In this position, 

 then, he woidd place two of the heaviest Annstrong guns, with their muzzles 41 

 feet apart, on an inclined slide, upon a tiu'n-table pbced within a fixed conical 

 fort, armour-clad, the sides of which sloped at an angle of 45°. Above this, for a 

 perpendicidar height of 4 feet, he would protect the guns and gunners with a 

 shield of iron plate, also at an angle of 45°. The shape of the fort would be a 

 truncated cone on a cylinder, like an extinguisher upon a candlestick. A second 

 cupola he believed might be added, and this woidd give an armament of foiu" guns, 

 which, if concentrated upon one point at short range, must have a crushing eflect. 

 But, to be of any use, the smaller vessel must be enabled to approach her large 

 antagonist without risk of having a shot sent through her bottom from the enemy's 

 depressed guns. The manner in which he proposed to fortify the gunboat was by 

 keeping all the vital parts well below the water-line, and covering them -with a 

 deck which would deflect upwards any shot that might reach it. As the boat was 

 only intended to attack ships, not forts, he presumed there was no need to appre- 

 hend a shot striking her at a larger angle with the horizon than 7°. Still at this 

 angle, to protect the sides of the vessel eftectually, the armom* must be carried at 

 least 4 feet above water and 3 feet below, possibly more ; but as this involved 

 a weight of 300 tons in plating alone, some other method of protection must be 

 sought. He hoped he had found this desideratum in a plan which aimed at 

 carrying out thoroughly the principle of deflection. His plan consisted of an arched 

 deck of inch iron resting upon two courses of timber, the extremities of the arch 

 being tied, so as to neutralize the outward thrust. He proposed that this shoidd 

 spring at the sides from 3 feet below the water-line, and that the crown shovdd rise 

 amidships up to the water-line, the crown being kept tolerably flat — the object being 

 to present so small an angle that even a flat-headed bolt shoidd glance off". The 

 space above the deck and between it and the water-line he proposed to pack with 

 some tough and resilient but light fibre, and these qualities he found combined in 

 the cocoa-nut fibre, which could be easily rendered incombustible by sal-ammoniac. 

 This fibre would offer a considerable amount of resistance to the penetration of a 

 shot, and in proportion to the resistance woidd tend to deflect the shot. The exact 

 amount of resistance which this mode of packing would afford could not be ascer- 

 tained without experiment, but the trial woidd not be expensive. He might be met 

 with the objection, that steel or iron was the substance which ofl'ered the gi-eatest 

 amoimt of protection proportionate to its weight. Granting this, he maintained 

 that there were circumstances under which iron alone coidd not be advantageously 



1861. 17 



