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LXXXV. Ohseroatioiis concerning a Method, of defending 

 Ships and Fortifications against Cannon Balls, and of causing 

 them to fy hack again on the Enemy. By Lewis Gom- 

 PERTZ, Esq.* 



HAVING made some experiments on a plan which I had 

 desio-ned for rendering ships and fortifications shot-proof, 

 and of causing several of the balls which might be fired against 

 them to return upon the enemy ; and having found my ex- 

 periments, which were on a small scale, to answer my expecta- 

 tions, I have here to explain the nature of the plan, with the 

 hopes that it may be further considered by those whose scien- 

 tific and practical information qualifies them for judging how 

 far it might succeed on a large scale. 



But before I enter into this description, I think it proper 

 to observe that the chief utility it may promise,^ is in its ap- 

 plication to merchant vessels, ships of passage, &c., and for 

 fortifications ; but for ships of war (as it could be adopted by 

 both parties) its effect would become neutralized, though it 

 seems that even in this case it would save the men from in- 

 jury, and would always be in favour of the weak and defen- 

 sive side; its nature being that of defending itself and of re- 

 turning the blows, but without any power of attacking, un- 

 less furnished with guns also. 



Fio-s. 4 and 5 show two views of a ship made on the 

 plan.'' Fig. 3 is a section of a side drawn larger, the form of 

 it beino- apparent by the drawing, in the three figures 3, 4 

 and 5;''the same letters refer to the same parts. NWAL is a 

 concave curve to return the balls which strike it : and PCO 

 is a triano-ular piece (extending beyond N M and L K) 

 which Toes' all round the ship to protect the most perpendi- 

 cular part of the curve WA from being struck directly (other- 

 wise it would be easily perforated), and which triangular piece, 

 on beino- struck somewhat horizontally, evades the balls, and 

 .Tuides them properly to the return part NWAL, so that 

 they follow the shape of it, and return. The i)art NM above 

 the curve where the port-holes are, and the part LKQ below 

 it, are made obfuiue, to evade those balls which strike theni, 

 the part NINI sending them upwards, and the part LKQ di- 

 recting them into the water, though it must be confessed that 

 some °of the former would thereby occasionally be thrown 

 into the rigging; there are a number of supports siiown near 

 P, fi<T. 4, and also faintly expressed in fig. 5, which fasten 

 the triangular piece to the siiip, and the more acute the out- 

 ward angle be, the less force will it generally be struck with. 

 * Coininunicutcd by the Author. 



Fig. 



