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282 upon them; in the explosion of bisulphide of carbon in a shoddy-oil factory in 1867; and in a celluloid-factory at Newark, New Jersey, in 1879. An explosion, believed to be of carbonic acid, which occurred in a French coal-mine, is supposed to have been caused by the formation, from the decomposition of pyrites, of sulphuric acid, which, finding its way to the limestone, suddenly generated large quantities of gas. M. Kuhlmann has shown that sulphuric acid mixing with ten equivalents of water may cause a very violent explosion. Of 156 colliery explosions, recorded in the United Kingdom during the present reign, the largest numbers occurred in February, March, and December, and the smallest number in May. Help in the study of disasters of this class is expected from meteorological investigations. Dust has recently been found to be a formidable explosive, and is now believed to have nearly as much to do with coal-mine accidents as firedamp. The charred appearance of the wood-work in coal-mines after explosions is ascribed to the deposition of a crust of scorched or melted coal-dust upon it. The fine dust generated in some of the processes employed in flouring-mills has been recognized lately as a very dangerous source of explosions, and attention has been directed to the contrivance of improvements in machinery to mitigate the perils to which the workers in tens of thousands of mills are exposed from it. The dangers arising from the liability of illuminating-gas to explode are great enough, but they would be much increased if a process should be adopted for depriving the gas of its odor. The explosive properties of gunpowder and petroleum in all the ways in which they are used are familiar enough and dreaded. The frequent damage to powder-mills by lightning may be ascribed not so much to the attractive power of the substances stored in them as to their isolated situation on marsh-lands near rivers. Insurance-tables show that 1,536 explosions of steam-boilers have taken place in the United Kingdom during the present century, killing 2,293 persons and injuring 3,259. In the United States, 1,299 explosions, killing 2,506 persons and injuring 2,612, are recorded as having taken place between October 1, 1867, and January 1, 1880. The largest number of these were in saw, planing, and wood-working mills, the next largest in steam-vessels, and the next largest of railroad locomotives. The greatest number killed and injured were on steam-vessels. The causes of explosions, according to English tables, appear to be about evenly divided between bad design, workmanship, and material, and ignorance or carelessness of attendants. A smaller number were attributed to defects arising in course of use. The most frequent and most destructive explosions in England appear to have been in iron-works and mines.

Earthquakes in England.—The earliest earthquake in England of which a record has been made took place in 1101, when, according to William of Malmesbury, the whole country was terrified "with a horrid spectacle, for all the buildings were lifted up, and then again set down as before." The next was in 1133, when houses were overthrown and flames were said to have issued from rifts in the earth. A third shock occurred in 1185, when, according to Holinshed, "stones that lay couched fast in the earth were removed out of their places, houses were overthrown, and the great church of Lincoln rent from the top downward." An earthquake in 1247, by which much property in London was damaged, was preceded for three months by a suspension of tidal movements on the English coast. On April 6, 1580, two shocks occurred, the second of which caused the church-bells to ring, threw some stones from St. Paul's Cathedral, leveled a part of the Temple Church, caused the death of two worshipers in Christ Church, by the falling of a stone from the roof, and threw a part of the cliff of Dover into the sea. Excitement prevailed for weeks afterward, business was seriously affected, riots were frequent, and prayers were prepared to bo offered night and morning for protection against further convulsions. Two undulatory movements of the earth, lasting together about four seconds, took place at noon on September 8, 1692, causing a great panic, but not inflicting very serious damage on property. A slight but evident shock, accompanied with a "great roaring," took plackplace [sic] on February 8, 1750, when bells were rung, "dogs howled, and fish jumped