1st Experiment.
Experiments in the Medway, England, 1870.—Countermine:—432 lbs. of compressed gun-cotton, enclosed in a 3/16" iron case. It was moored at a depth of 37' below the surface of the water.
Submarine mines:—A series of similar cases containing coal dust, &c., were moored at distances of 50' to 100' from the countermine, and 37 feet below the surface.
Effect of explosion:—The submarine mine at 80' distance was completely destroyed; the dome of its circuit closer was dented in.