lime, with certain precautions, to develop a heat capable of setting on
fire incense or any other material that is more readily combustible,
such as sulphur and phosphorus. The same author points out still another
means, and this consists in hiding firebrands in small bells that were
afterward covered with shavings, the latter having previously been
covered with a composition made of naphtha and bitumen (Greek fire).
As may be seen, a very small movement sufficed to bring about
combustion.--_A. De Rochas, in La Nature_.

* * * * *




TORPEDO BOATS.


There are several kinds of torpedoes. The one which is most used in the
French navy is called the "carried" torpedo (_torpille portee_), thus
named because the torpedo boat literally _carries_ it right under the
sides of the enemy's ship. It consists of a cartridge of about 20
kilogrammes of gun cotton, placed at the extremity of an iron rod, 12
meters in length, projecting in a downward direction from the fore part
of the boat. The charge is fired by an electric spark by means of an
apparatus placed in the lookout compartment. Our engraving represents an
attack on an ironclad by means of one of these torpedoes. Under cover of
darkness, the torpedo boat has been enabled to approach without being
disabled by the projectiles from the revolving guns of the man-of-war,
and has stopped suddenly and ignited the torpedo as soon as the latter
came in contact with the enemy's hull.