Underwater Photogrammetry for Archaeology- The Venus Project Framework

A time delay device adapted to cooperate with a firing device. The time delay device comprises a piston cooperating with the firing device, a spring to move the piston between a first position in which the firing device remains in a non-operating condition and a second position in which said firing device is allowed to operate, a retractable pin to hold the piston in the first position, a reservoir of fluid adapted to be acted upon by the piston and communicating with a length of small bore or micro-bore tubing whereby upon movement of the piston fluid will be displaced from the reservoir through said tubing, with the rate of movement of the piston, and therefore the time for the piston to move from the first to the second position under the action of said spring, being dictated by the viscosity of the fluid in the reservoir and the length of the tubing. A predetermined time delay is therefore produced between actuation by retraction of the pin and movement of the piston under the action of said spring to the second position to allow operation of the firing device. A temperature compensating device is also disclosed.