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THE POPULAR SCIENCE MONTHLY. 



upon them ; in the explosion of bisulphide of 

 carbon in a shoddy-oil factory in 1867 ; and 

 in a celluloid-factory at Newark, Xew 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 vio- 

 lent 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 ei^pected from 

 meteorological investigations. Dust has re- 

 cently been found to be a formidable explo- 

 sive, and is now believed to have nearly as 

 much to do with coal-mine accidents as fire- 

 damp. 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 recog- 

 nized lately as a very dangerous source of 

 explosions, and attention has been directed 

 to the contrivance of improvements in ma- 

 chinery 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 fa- 

 miliar 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 injur- 

 ing 2,612, are recorded as having taken 

 place between October 1, 1867, and Janu- 

 ary 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 ap- 

 pear 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 Malmcsbury, 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 over- 

 thrown and flames were said to have issued 

 from rifts in the earth. A third shock oc- 

 curred in 1185, when, according to Holins- 

 hed, " 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 down- 

 ward." An earthquake in 1247, by which 

 much property in London was damaged, 

 was preceded for three months by a sus- 

 pension of tidal movements on the English 

 coast. On April 6, 1580, two shocks oc- 

 curred, 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 

 fretjuent, and prayers were prepared to bo 

 offered night and morning for protection 

 against further convulsions. Two undula- 

 tory movements of the earth, lasting to- 

 gether about four seconds, took plaoe at 

 noon on September 8, 1692, causing a great 

 panic, but not inflicting very serious dam- 

 age on property. A slight but evident 

 shock, accompanied with a " great roaring," 

 took plack on February 8, 1750, when bells 

 were rung, " dogs howled, and fish jumped 



