REUNITED WITH HIS FAMILY IN ENGLAND 207 



mines when he explodes them, provided only he has 

 established some mark or point which, on being reached 

 by the enemy, should serve as his signal. The area of 

 destruction of one fougasse, properly constructed, with 

 a charge of twenty or twenty-five pounds of powder, may 

 be assumed to be that of a circle seventy-five or eighty 

 yards in diameter. Twenty mines would therefore serve 

 for a mile. Several miles may be planted in a night, 

 and the assailants may be enticed or invited out in the 

 morning. Passes before an invading army may be 

 mined in advance, and thus, if he cannot be destroyed, 

 his progress may be so retarded by dummies or sham 

 mines as almost literally to compel him to dig his way. 



'The power to telegraph through these torpedoes is 

 of little consequence, inasmuch as there need be but one 

 station and one operator. Using the testing-fuse man- 

 ufactured by Abel, and a weak voltaic current, the 

 operator can at any time satisfy himself as to continuity. 

 Thus bridges and gulfs or breaks are not required for the 

 land as they are in sea-mining. Ebonite has the further 

 advantage on land that it takes but a single wire. 



'Torts may be protected against assault, and your 

 own rifle-pits from occupation by an enemy, simply by 

 a proper distribution of those new engines of war. They 

 may be planted line within line, and one row above 

 another, and so arranged that volcanoes may be sprung 

 at will under the feet of assaulting columns. 



"The only attempt that was made in the late American 

 war to bring the electrical torpedo into play on the land 

 was made by the Confederates at Fort Fisher, in 1865, 

 just before its fall. The narrow landspit over which the 

 attacking party had to advance was mined. The officer 

 in charge used the magneto exploder. But the mines 



