One of the most frightful effects of thunder on ships is fire, which it drives from one part of the vessel to another. Under ordinary circumstances it is usually local, and easily extinguished; but when it seizes on various parts of the ship at once, as when struck by lightning, then destruction becomes inevitable. In 1793 the _King George_ from Bombay was sailing up the river at Canton, when an electric spark, followed by a violent clap of thunder, grazed the mizzen-mast, and disappeared in the hold, after killing seven men. Seven hours later it was discovered with consternation that the hold, full of an inflammable cargo, was on fire. It spread rapidly over the whole ship, which it burned to the water's edge. The ship _Bayfield_ from Liverpool was struck by lightning November 25, 1845. Instantly the deck was seen covered with globes of fire and large sparks, which set fire to the vessel. As it threatened the powder-magazine, the captain decided to abandon the ship. A rush was made for the boats, but as only thirty pounds of bread could be saved, many perished of hunger and thirst. Often, indeed, the explosion of the powder-magazine makes the catastrophe even more terrible. Thus, in 1798, the English vessel the _Resistance_, was blown up in the Straits of Malacca. Only two or three of the crew were saved. But lightning plays more tricks with the compass than with anything else when it visits a ship. The vibrating, quivering, magnetic needle is often paralyzed by the electric current; sometimes its poles are reversed, or the points, disturbed by the passage of the spark, deviate, and no longer responding to the magnetic pole, mislead and move hither and thither. Sometimes they even lose all their magnetic properties. These changes in the compass often lead to disastrous consequences. Many cases are known of ships being steered to destruction through the deviation of the compass. Arago tells of a Genoese ship which, about the year 1808, sailing for Marseilles, was struck a little way off Algiers. The needles of the compasses all made half a revolution, although the instruments did not appear to be injured, and the vessel was wrecked on the coast when the pilot believed he could round the cape to the north. This may account for the total disappearance of certain ships. Some ships, like certain individuals and certain trees, appear in particular to attract the electric fluid. We have many records of vessels struck several times in the course of a single electric storm. Here are a few:-- On August 1, 1750, the _Malacca_ was struck repeatedly. In 1848, the _Competitor_ was struck twice within an hour. At the beginning of December, 1770, between Mahon and Malta, the ship of a Russian admiral was struck three times in a single night. On January 5, 1830, in the Straits of Corfu, the _Madagascar_ received five destructive discharges in two hours.