Greatly informative post. Powerful intellects were at work on both sides in the Civil War.
Didn’t the Hunley survive long enough after the torpedo exploded for the captain to flash a blue lens success signal, and that this was seen & recorded on shore?
Curiously, the current Friends of the Hunley (of which I'm a Charter Member) website refers to a "magnesium" blue light. However, the lantern with a blue lens that was recovered was a small, handheld carbide lamp -- similar in principle to those used by miners -- and certainly bright enough for the purpose of signaling over 4-5 miles.
When the X-rays of the recovered lamp were made available, I immediately located a very similar carbide lantern online. I hope to be able to examine that recovered lantern -- once it is freed from its incrustation...
There is a replica of the Hunley lamp on display at
http://travel.webshots.com/photo/2638440590103680599DJwFEh.
BTW, "carbide" lamps are technically acetylene lamps, since they meter water into a chamber containing solid calcium carbide, thus releasing acetylene gas, which burns as a brilliant white jet.