Various technical innovations from the U. S. Navy, including an aeroplane catapult.
San Francisco, United States of America, U.S.A.
Title: "New planes in catapult test! Navy's nervy pilots guide sea planes on their initial hop from deck to prepare them for flee manoeuvres".
Shots are same or similar to those in the short version of this story.
Intertitle: "Even a seaplane can be balky - see how stubborn this one is!"
M/S of a plane taking off the catapult, the film stops and is then reversed so we see the plane fly back onto the catapult. More shots of the biplane taking off and flying over ships in the bay.
Intertitle: "Continuing tests in another important department; laying high-powered TNT mines to try out their efficiency as a part of the harbour defence".
M/S of men using a small crane on the side of a moving ship to lower mines into the water. Top shot of the mine dangling from a chain over the water, it is released and drops in the sea with a splash.
Intertitle: "Mines, exploded from shore stations, easily dispatch the dummy targets".
Point of view shot from a moving vessel of a submarine skimming along the service. Various L/Ss, taken from a moving vessel, of an explosion in the sea.
Note: looks like this is the American Pathe version - some American spellings on title cards.
Note: please see also SHOT IN THE AIR (short version).