A Better Barrel

In “Working with Working Models” (Fall 1985), Benjamin Lawless showed a patent model for a Dahlgren-like gun designed by John Ericsson and described the rings around the barrel as providing cooling. But overheating from rapid fire was a small problem in 1864 compared with the tendency of large iron cannon to burst. A host of inventors on either side of the Atlantic labored furiously to develop composite cannon with greater strength and endurance, and Dahlgren, for one, patented circular plates stacked and shrunken into place for added reinforcement. I suspect that the fins on Ericsson’s gun were likewise intended not for cooling but for increased strength.

Benjamin Lawless replies: Mr. Olmstead is right, and I was wrong. The patent states that the purpose of the wroughtiron bands was “to obtain the necessary strength with the least weight of metal.”