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Mid point of cordaau

'Cordeau

Ficure 8. Pierre-Eugène Marcellin Berthelot (1827-1907) (Photo by P.

Explosive under test'

Fioubs 9. Dautriche Method of Measuring Velocity of Detonation. From the point A the explosion proceeds in two directions: (1) along the cordeau (of known velocity of detonation), and (2) through the cartridge

of explosive which is being tested and then along the cordeau. When the two waves in the corde&u meet, they make a marie in the lead plate upon which the cordeau is resting.

placed upon a line scratched in the lead plate at right angles to the direction of the cordeau. When the detonator in the end of the cartridge of explosive is fired, the explosive wave first encounters one end of the cordeau and initiates its explosion from this end, then proceeds through the cartridge, encounters the other end of the cordeau, and initiates its explosion from that end. The explosive waves from the two ends cf the cordeau meet one another and mark the point of their meeting by an extra-deep, sharp furrow in the lead plate, perhaps by a hole punched through it. The distance of this point is measured from the line where the midpoint of the cordeau was placed. Call this distance d. It is evident that, from the moment when the near end of the cordeau started to detonate, one explosive wave traveled in the cordeau for a distance equal to one-half the length of the cordeau plus the distance dt while the other explosive wave, during the same interval of time, traveled in the explosive under examination a distance equal to the distance between the inserted ends of cordeau, then in the cordeau a distance equal to one-half its length minus the distance d. The times required for the passage of the explosive waves in the cordeau are calculated from the known velocity of detonation of the cordeau used; thence the time required for the detonation of the column of explosive which

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