AT FORT INDEPENDENCE 175 



part of the three years in question, General Rodman was ex- 

 perimenting with great guns at that station. I used to go to 

 the fort on Friday afternoons and to bide there through Satur- 

 day, working as a soldier or as a clerk, doing the diverse duties, 

 including those of inspection and reports. In this way, by giv- 

 ing perhaps one hundred days to the task, I became tolerably 

 well-instructed in the principles and practice of artillery work. 

 There was much exercise in sighting guns and a fair amount in 

 target practice, where I was allowed to "lay" the larger pieces, 

 criticising the pointing of the men before they were fired, so 

 that with my previous practice with the rifle, I could count 

 myself fairly well-trained in the art of the gunner. All this left 

 me, of course, below the station of the professional soldier, but 

 it made me distinctly more competent than the novice or even 

 most of the young men who as volunteers went into the business. 

 I was particularly interested in General Rodman's experi- 

 ments on the pressure of gunpowder when fired. For this in- 

 quiry he had bored cylinders in the walls of his pieces, as I 

 remember them, up to ten inches in diameter; each of these 

 cylinders was fitted with a piston having a ridge-shaped head, 

 which rested on a plate of soft composition metal. When the 

 charge was fired, these cylinder-heads indented the plates in 

 proportion to the pressure which they had received. I was 

 allowed to take some share in these testings, which were most 

 carefully done, and obtained through this chance a sense of 

 accurate methods which helped me greatly. In each series of 

 tests the gun was fired with increasing charges until it was 

 burst ; then the fragments were studied to determine the char- 

 acter of the metal and the seat of the rupture. So, too, after 

 each discharge the interior of the bore was examined with the 

 speculum, to ascertain the process of developing the incipient 

 cracks which form long before the body of the metal gives way. 

 The experience thus gained I found very useful in the study of 

 dredging machinery, such as forty years afterwards I had 

 to deal with in Montana. Rodman and his helpers had the 



