TRANSACTIONS OF THE SECTIONS. 219 



On tJie North-China and Japan Submarine Gables. By William Hoopek. 



On the History of the Shell that won the Battle of Sedan. By AV. Hope, V.C. 



On Frictional Screvj Motions. By G. Lafder, C.E. 



On Hammering and Stone-dressiny Machinery. By J. H. Llotd, M.D. 



On the Defence of Liverpool by Floating Forts. By Samtjel J. Mackie, C.E. 



Livei"pool, the second commercial port in Great Britain, is at tliis time totally 

 undefended, and cannot be protected by shore-forts. The proposed new forts and 

 the proposed fleet of small unarmed one-gun boats might defend, but could not 

 protect, either the town or the docks from injuiy by an enemy's fire. There is 

 only one way of effectuall}' securing for the ports and shipping of the Mersey im- 

 munity from bombardment, namely, the closing of the two great shipways, the 

 (Queen's and the Horse channels, and thus keeping the hostile guns beyond their 

 range, the carrying, in fact, the sea-tight ten or twelye miles awaj' from the mouth 

 of the riyer. bhips and shore-forts cannot accomplish this ; and it can be eft'ected 

 only by floating forts of proper and suitable construction. One broadside-ship is 

 at best only good against two others ; one turret-ship could only fight one other. 

 The defences of Liyerpool must be prepared to meet a fleet. Any number of un- 

 armoured yessels could not eifect this yital end. Unprotected vessels carrying 

 single guns would be certain, sooner or later, to be hit and sunk. Our heaviest 

 guns, the 600-pounders, would just pierce the battery-armour of the ' Hercules,' 

 but woidd not penetrate her water-line belt at 150 yards. Our first-class iron- 

 clads would be perfectly safe at two miles; but any one of the projectiles from 

 their armaments woidd sink an unarmoured gun-boat at five miles, indeed where- 

 ever it could hit her. The unarmoured vessel, however, could not Iceep out of 

 harm's way : she must come within 3000 yards to attack any iron-clad, for her guns 

 must punch the armour of her adversary to do any injury at all ; and there would 

 be no chance of sinking the iron-clad until her belt was ruptured. It is not right 

 to assume that gun-boats would not be hit, small and active tliough they be. In 

 practice made at Shoebniyness in 1868 the bull's-ej-e of a target painted to repre- 

 sent the port-hole of a ship had three shots put into it by a 2o0-pounder gun out 

 of nine rounds, all the rest being- within 2 feet of the mark. The running-target, 

 6 feet by feet, is repeatedly hit by the ofiieers and men of the School of Gunnery. 

 The smallest vessels being then so much larger tlian these objects, there are no sub- 

 stantial gi'ounds for the idea that they should be able to attack with impunity iron-; 

 clad men-of-war. 



What is really wanted for the protection of Liverpool is at least two impregnable 

 iron floating forts, capable, even if by any disaster or by design they should be sunk, 

 of fighting some of their gmis above water. Such forts can be made, and the piin- 

 ciple of construction advocated has already passed the bounds of mere hypothesis. 

 Any fort, however strongly built, must get injured by the terrific blows of modern 

 projectiles ; and as water finds access only too readily through cracks and fissures, 

 It is right to provide a resource against the last emergency. Another consideration 

 is that the battery afloat might be in danger of being overpowered by ramming, 

 which could be avoided by voluntaiy submergence on a shoal or on the sea-bed in 

 sufficientlj' shallow water. Eifled guns (in other words, weapons of precision) re- 

 quire, above all things, a perfectly steady and stable platform. Accm-ate aim is the 

 primary consideration in their use. Ships are adapted for sailing, not for gun- 

 cari-iages. The proper lively motion of a ship is absolutely antagonistic to 

 steadiness of platform, blasts are not required in a floating fort; steam-power 

 applied as hydraulic propulsion can give all the propulsion required. 



The four-rayed forts proposed by Mr. Moody, an able and most experienced 

 captain in the merchant-service, have perfectly all the qualities required. In prin- 



