If you think Lt. John Adolphus Bernard Dahlgren just sat down and used shape templates to dream up his artillery designs, you are mistaken. I've been going through his papers in the Library of Congress and have found that he had a definite method in his work. As you may know, he designed systems of boat howitzers and naval guns used by the US Navy from about 1850 until long after the Civil War.
One "unknown" howitzer was never produced in quantity, only one was built, plus (I think) one model of it. That was his ultra-heavy 12-pounder bronze howitzer with a tube weighing over 1300 lbs. I don't know that this prototype howitzer survived, I suspect it got melted down after the Civil War. I think the fine model I showed in another discussion, that's now at the Lincoln Museum in IL, identified as "Tad Lincoln's Cannon" is actually the "arsenal" model of this howitzer, made at the Washington Navy Yard.
Anyway, while I was looking for something else, I blundered into Dahlgren's small notebook with information on boat howitzers, and in it were the pages shown, with his calculations for the new weapon. You can see he was pretty close, because when the full-size barrel was done, it weighed 1338 lbs.
From what I've seen in the papers I've been looking through a few things became clear to me. Dahlgren was a genius, as competent a mathmatician as anyone in the 19th C., and he was an extraordinarily thorough engineer. He was also very dedicated to his work; the output of calculations, memoranda, reports, books, etc. was truly phenomenal.
See if you engineers can follow his calculations, which I think are basically for the weight and preponderance of the howitzer.
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