Situated in the conning tower, the Torpedo Data Computer Mark III was the standard fire control device used by U.S. Navy submarines during the first half of WWII. An electro-mechanical, analog computer, the TDC provided fire control solutions through a variety of inputs, including submarine course and speed, estimated target course,speed and range, and torpedo type in use. Originally printed by the Arma Corporation and the U.S. Navy, this Mark 3 manual provides a fascinating glimpse inside this mechanical wonder. Please note, due to quality issues with the original document, some pages may be slightly sub-standard. Care has been taken to preserve the integrity of the original text.