412 Defence of Ships against CannoH Balls. 



inside of the board ST was (perhaps improperly) coated with 

 iron; the bullets were of lead, and about one-third part of the 

 weight of a musket-ball, and they were fired from a blunder- 

 buss well charged. They made very slight long dents not 

 l-8th of an inch deep in the deal ; and when the additional 

 board TS was not used, they flew upwards and perforated 

 the iron return part W ; but when the boaid TS was added, 

 they each made a dent also near the narrow part I, and fol- 

 lowed the return part W ; and then they returned against a 

 deal board placed behind the stock of the blunderbuss, and 

 left moderately deep impressions on it. 



I also made experiments on the plan of figs. 3, 4, 5, though 

 on a still smaller scale, and on a model which was made of 

 deal, but with the same accoi'dant results^ to the remarks I 

 have made. 



I rather think that a thin coating of iron on a wooden side 

 would not be advantageous, as the iron would bend away 

 from that part of the ball which it should be in absolute con- 

 tact with, and the ball would then be improperly directed : 

 therefore, whatever substance be employed, it should be of 

 such a nature as to fit the ball as it goes, and the grain of the 

 wood, of which the side &c. is made, should be m the direc- 

 tion of the motion of the ball, not transversely. 



Ii is scarcely necessary to notice, that if the object of re- 

 turning the ball be dispensed with, the side may simply be 

 formed into a triangle COP, fig. 3, 4 and 5, without the 

 concave part NWAL; and in fig. 1, without the return part 

 W, and boai'd TS, though the balls would be thrown more 

 into the rigging by this means. 



The lower part L should perhaps rather bend upwards to 

 cause the balls to fly a little upwards in returning, because 

 those which come against the side H, fig. 3, 4 and 5, will not 

 only be lowered the whole distance between H and L, but, 

 as they will return rather more slowly than they came, they 

 will also be attracted downwards with more force by the 

 power of gravity ; the curve will likewise be more effective if 

 made smaller at the entry NL, than at the other part WA. 

 I have also to add that a coating of grease on the side &c. is, 

 it seems, of service. 



But I am fully aware, that however the experiments might 

 have succeeded in miniature, the great force of a cannon ball 

 might defy them all, though it is known that slight obstruc- 

 tions affect their motion when opposed to them obliquely. It 

 also remains to be further tried, whether the balls would be 

 returned with sufficient force. 



Any person repeating these experiments should (in order 



to 



