Perkins" 1 Steam Engine. 43 



country defended by this kind of artillery, would never be 

 invaded, and I am very confidently of this opinion. 



As soon as this machine is completed, it is to be exhibited 

 to this government, and to several engineers from other 

 powers, who are over here for that purpose. I have no fears 

 for the result, neither has Mr. Lukens, since he witnessed 

 the experiment made for the French government. He saw 

 the steam gun discharge at the rate of from 500 to 1000 

 balls per minute, and the steam blowing off at the escape 

 valve, during the whole time ; he is equally confident with 

 myself, that the steam may be kept up in such a man- 

 ner as to discharge a constant stream of balls during the 

 whole day, if required. As regards economy, I am within the 

 truth, when I say, that if the discharges are rapid, one pound 

 of coals will throw as many balls as four pounds of powder. 

 It has been stated as an objection to the steam gun, that 

 it would take too long to get up the steam, in case of an 

 attack. To this I answer, that a very small quantity of fire 

 will keep the generators sufficiently heated, when there is no 

 water in them : and that when there is any chance of their 

 bejng suddenly wanted, they should be kept heated in this 

 way. The heat of the generators would last long enough to 

 give off steam ; until the fire is sufficiently increased to fur- 

 nish a constant supply. For naval purposes this cannot be 

 an objection, as the steam must always be up. Lord 

 Exmouth, after witnessing a few showers of lead observed, 

 that he believed the time would come, when a steam gun 

 boat with two steam guns in her bow, would conquer any line 

 of battle ship ; and Sir George Cockburn said, that the mis- 

 chief of it was, it would be to nations what the pistol was to 

 duellists, it would bring all, whether strong or weak, upon a par. 

 To prove the safety of my engine, I have worked it under 

 a pressure of 1 400 lbs. to the square inch, or at a hundred 

 atmospheres, and cut off the steam at one twelfth of the 

 stroke ; this was merely to manifest what could be done 

 with perfect security. My usual pressure is 800 lbs. per inch 

 cutting off at one-eighth, and letting the steam expand 

 to below 100 lbs. per inch. I let off at the dead point, at- 

 one flash ; the manner of doing this I long to explain to you. 

 but must first get my last patent sealed. 



I am informed that our friend, Dr. Hare, thinks I have 

 ventured beyond my depth ; in this he is not singular, nor do 

 I wonder that such an idea should prevail, after the publica- 



