182 REPORT—1863. 
point P, has three points of minimum and two of maximum velocity of gliding; 
while every water-line which passes through or beyond P has only two points 
of minimum and one of maximum velocity of gliding. Hence the latter class 
of lines causes less commotion in the water than the former. 
14. On the water-line P Q which traverses the point P itself, the velocity of 
gliding changes more gradually than on any other water-line haying the same 
proportion of length to breadth. Water-lines possessing this character can be 
constructed with any proportion of length to breadth, from »/3 (which gives an 
oval through L and Pp to infinity. The finer of those lines are found to be nearly 
approximated to by wave-lines, but are less hollow at the bow than wave-lines are. 
15. The author shows how horizontal water-lines at the bow, drawn according 
to this system, may be combined with vertical plane lines of motion for the water 
at the stern, if desired by the naval architect. 
16. In this, as in every system of water-lines, a certain relation (according to a 
principle first pointed out by Mr. Scott Russell) must be preserved between the 
lengths of the after-body and fore-body and the maximum speed of the ship, in order 
that the appreciable resistance may be wholly frictional and proportional to the 
square of the velocity (as the experimental researches of Mr. J. R. Napier and the 
author have shown it to be in well-formed ships), and may not be augmented by 
terms increasing as the fourth and higher powers of the velocity through the pro- 
pagation of diverging waves. 
Description of Corrugated Armour of Steel or Iron for Ships of War. 
By Grorce Reprorp. 
The method proposed is founded upon two principles of strength—cohesive 
strength and mechanical strength. The plates, being made of steel, hardened and 
tempered as nearly as possible up to the cohesive strength of the Whitworth shot 
and shell, are of two kinds—one thick and corrugated, the other thinner and plain. 
The steel corrugated plates, which are 3 inches thick, are placed upon the thinner 
plates of 1 inch, also tempered, and bolted through the skin of the ship—to the ribs 
in an iron ship, or to the timbers in a wooden one. If iron plates of the corru- 
gated form were backed with an inch plate of steel, hardened and tempered, the 
author thought that they would prove impenetrable; and even smooth iron plates 
of 4 inches, thus laid upon steel, would be more effective than iron plates even of 
7 inches thick, backed ‘a timber. The author states that the advantages of the 
plan proposed are, besides the protection of the ships, the reduction of the weight 
of armour much below that contemplated for the new ships of war, and below that 
of the Warrior, the Achilles, and the Minotaur. The saving of at least 1 inch in 
thickness of plates would give a reduction of 100 tons; and, if it should be found 
that timber backing can with this armour be dispensed with (a point now so much 
the subject of inquiry), the reduction of weight would be about 250 tons in a ship 
of the Warrior class. The extra cost would be, to a great extent, met by the 
saving in the thickness of plates and the timber backing. The author looks to 
the development of the eoncals of steel, and the conversion of iron into that far 
stronger metal, for the acquisition of a lighter and impregnable armour for ships of 
war, a desideratum which can never be obtained by merely increasing the thick- 
ness of iron to any extent a ship could carry and be fit for ocean service. The 
author stated that steel plates of this kind could be manufactured at about one- 
third more than the cost of the best iron armour-plates. 
Rifled Ordnance. By G. Ricwarns. 
The author suggested and illustrated a sguare-bore gun introduced by him, to 
give greater initial velocity to projectiles than was attainable by any plan yet pro- 
posed, inasmuch as the area of the square bore was at least 20 per cent. more than 
that of the circular bore containing a shot of the same diameter, thereby exposing, 
by using a wad or sabot, a greater surface to the impact of the ignited powder. 
The author also showed a method of loading heavy ordnance (applicable to sea 
service) by means of a loading-rod. The method of loading the gun was by means 
of a loading-rod passing through a perforation in the breech of the gun, and thence 
