310 



Mr. Reed on Iron- clad Ships. 



[Mar. 19, 



Taking the cost per ton at s6;)5 (which is the average cost per ton of 

 tonnage for the hulls of armour-clad ships), the saving made by adopting 

 the new ship of the * Bellerophon ' type would amount to ^283,250, or 

 considerably more than a quarter of a million sterling. It must also be 

 considered that the ship of the * Bellerophon ' type would cost less for 

 maintenance and repair, and be much handier in action. 



The last investigation in the Paper is purely theoretical, and consists of 

 a determination of the dimensions which would be required in two ships of 

 which the horizontal sections are curves of sines, and which are prismatic 

 vertically, if they were built with the same weight per square foot of hull 

 (say 1 ton) as the * Bellerophon,' but carried twice the weight of armour 

 per square foot (say ^-^ ton). In these cases the bottom is taken to have 

 weight as well as the sides ; the speed for both is 14 knots, the draught of 

 water is 25 feet, and the depth of the armoured side 24 feet. One of the 

 ships is seven times her breadth in length, and the other is five times. 

 Professor Rankine's rule for the calculation of horse-power and speed is 

 employed ; and the same conditions of engines &c. are assumed as have 

 been indicated previously. The larger ship carries 1350 tons additional 

 weights, and the smaller 900 tons. 



The results obtained for these ships are as follows, when expressed in 

 round numbers : — 





Larger ship. 



Smaller ship. 





585 feet. 

 84 „ 

 1267 H.P. 

 8890 „ 

 7586 tons. 

 6124 „ 

 2540 „ 

 1350 „ 

 17600 „ 



425 feet. 

 85 „ 

 980 H.P. 

 6860 „ 

 5540 tons. 

 4470 „ 

 1960 „ 

 900 „ 

 12870 „ 



Weight of hull 



„ armour and backing . , 

 ,, engines and coals .... 



These results are very different in detail from those obtained in the 

 cases based on the actual trials of the 'Bellerophon' and 'Minotaur.* 

 The 2000 H.P. which is needed by the larger ship above the power 

 required by the smaller ship, is principally due to the difference between 

 the immersed surfaces of the two ships, and is spent in overcoming friction. 

 The immersed midship sections, it will be remarker!, only differ by a very 

 small amount. 



This last investigation serves to show that, the theoretical best form of 

 ship being taken, and the most recent rule being applied in the calcula- 

 tions, the speed of 14 knots can be obtained in the short type of ship at a 

 surprisingly less cost and size than the long type requires ; and this result 

 agrees with that of the preceding investigation based on actual trials. 



