Antiaircraft gun carriage. The elevating mechanism is assembled on a thirty-seven-millimeter antiaircraft gun carriage nearing completion. Care and precision is the watchword in the assembling of these mechanisms. A 300-mile-per-hour target requires a precision instrument to allow the gunner to stay with it. War program production scene in one of Pennsylvania's heavy industry plants now converted to the production of vitally needed military equipment. AETNA. Ellwood City, Pennsylvania