Concentrator of elastic waves
  This article is dedicated to an opportunity of concentrating elastic waves in the iron and water cones on the square of the cone vertex of the order of one square centimeter. The square of the base of the cone is equal to one square meter, its height one meter. The calculations assume that the cone hexogen network lying in the cone basis explodes during the time of one microsecond and causes an explosive wave converging to the vertex of the cone. It is shown that this explosive wave can accelerate the body having a mass of three grams to speed five kilometers per second. 
S. N. Dolya
physics.class-ph