April 1, 1892.] 



KNOWLEDGE. 



71 



spectra of several binaries by private letter in July, 1890, 

 when I was compiling my catalogv.e of binary star orbits. 



Yours faithfully, 

 March 18th, 1892. .7. E. Gore. 



PERIODICAL COMETS DUE IX 1892. 

 Tn till' Editor of Knowledge. 



Sir, — lu reference to my short article on this subject in 

 your February number, will you allow me space for a few 

 words to mention that M. Gautior has written a letter to 

 the (Jbsen-dtori/ pointing out that I had overlooked an 

 investigation of his own (publisl\ed in No. 265G of the 

 A.itrojiomisi-he Xaclirichten) on the motions of Tempsl's first 

 periodical comet, which shows that, in consequence of 

 great perturbations produced by the action of Jupiter upon 

 it between 1879 and 1885, the duration of its revolution 

 was increased by some mouths, so that the last return was 

 not due until the autumn of 188.3, and another may be 

 expected in the month of April next. That comet was 

 discovered by Tempel at Marseilles, on the 3rd of April, 

 1867, and was observed at the returns of 1873 and 1879, 

 but has not since been seen. In all those years it passed 

 its perihelion in May, but, according to M. Gautier's 

 calculations, the subsequent lengthening of its periodic 

 time was such that the next perihelion passage probably 

 occurred on the 25th of September, 1885. It was not, 

 however, seen, he remarks, on tliat occasion "par suite 

 d'un concours de circonstances defavorables." But, as it 

 has kept at a respectful distance from Jupiter since 1885, 

 there is every reason to suppose that it has suffered no 

 further important change in its period, and that it will 

 return to perihelion in the early days of April in the 

 present year. Yours faithfully, 



Blackheath, February 5th, 1892. W. T. Lynn. 



OX THE CAUSE OF EARTHQUAKES. 

 To the Editor of Knowledge. 



Dear Sir, — Nearly forty years ago a tremendous explo- 

 sion occurred at Gateshead, during a great fire. It shook 

 the whole of Newcastle, and was heard at Tynemouth, 

 and ten miles out at sea. Burning rafters were carried 

 high into the air ; some of them falling on the other side 

 of tlie Tyne caused a tire in Newcastle, and one rafter fell 

 in my works, on the Gateshead side of the river, three- 

 quarters of a mile away from the scene of the explosion. 

 I visited the ruins and saw that the dcliris was arranged 

 in the form of a crater, and that inside the crater there 

 was a pool of water thirteen feet deep. 



The fire and explosion had been the cause of several 

 deaths, and a very searchhig enquiry was made at the 

 inquest as to the cause of the explosion. There was a 

 general belief amongst the inhabitants of Newcastle that 

 gunpowder had been stored in tlie warehouses, contrary to 

 the law, and much indignation was expressed against the 

 warehouse owners, but the evidenc3 of Mr. Hugh Lee 

 Pattison, which I enclose, goes conclusively to show 

 that the explosion was due to the sudden generation 

 of steam. I shall never forget the sensation produced 

 at the inquest when the witness said, " To produce 

 an explosion another element is wanted." He paused, 

 and everybody expected the word "gunpowder" to 

 follow. But he went on, " and that is water," and 

 he ultimately succeeded in convincing the jury that the 

 water they had looked upon as an element of safety was 

 more dangerous than gunpowder. 



It seems to me that if water can produce such a 

 tremendous concussion by its sudden conversion into 



steam when it is confined by warehouse floors, with a few 

 tons of goods upon them, its explosive force would be 

 sufficient to shake the earth, and throw down buildings on 

 the surface, if it were suddenly converted into steam at a 

 great depth. I tliiiik that it is pretty generally admitted 

 that volcanic eruptions are always acsompanied by a great 

 evolution of steam, which continues to issue and form a 

 white cloud steaming away from the volcanic vent long 

 after the first outburst has ceased ; and it seems to me 

 much more probable that the great shaking of the earth's 

 crust, as well as the noises heard during some earthquakes, 

 are produced by sucli explosions, rather than by the 

 grinding together and slipping of strata along a line of 

 fault, as has been suggested by modern theorists. 



Yor.rs faithfully, 



George Crawsh.vy. 



FROM TUK REPORT OF THE INQUEST. 



Date of Explosion, October (Hh, ISoi. 



" Hugh Lee Pattiiisoii was then swovn ami gave his evidence : — He- 

 said ho had h)oked to the contents of the warehouse furnished him by 

 the coroner, and wag of opinion that not one of the substances was 

 explosive by itself. He was also of opinion that not one of the sub- 

 stances would become explosive by being roughly mixed together. 

 He thought he could go further and say that hardly any three of 

 them would become explosive. Daring these two days and this 

 morning, previous to this enquiry, he had made several expei'iments, 

 not because he felt any philosophical doubt, hut to make assurance 

 doubly sure. He had melted nitrate of soda, and when perfectly fluid 

 and red-hot he had poured it into melted brimstone, and there had 

 been produced certainly intense heat, but no explosion. He had 

 introduced into melted nitrate of soda, while red-hot, melted guano, 

 melted zinc and coal tar, that was all the explosive materials, and 

 there had been no explosion ; there simply took place deflagration, 

 i which, act'ording to Crabbe, mea.it a gradual sparkling combustion of 

 i any substance without violent explosion — a term particularly applied 

 to combustion applied to nitre. It followed, therefore, that the con- 

 tents of the warehouse alone would not explode. There wanted 

 another element, and that element was water; for we had abundant 

 evidence that when water came into contact with intensely hot and 

 melted saline matter generally a violent exijlosion took place. This 

 he had also proved by experiment, by introducing a small cpiantity of 

 water into a crucible and also into a large jar, both containing 

 incandescent nitrate of soda, deflagrating with sulphur, and in 

 each ease the vessel was shivered to pieces with a loud explo- 

 sion, and he produced the pieces in court. Various other 

 experiments of the same nature were made by himself and assistants, 

 all with the same results, and, in support of the same view, he read 

 from the London, Edinburgh, and Dublin ' Philosophical Magazine ' 

 for 1850, a paper by Dr. Hare, of Phdadeljihia, detailing experiments- 

 which showed that "an explosion similar to the present, which occurred 

 in New York in 1845, had occurred from this cause. Mr. Pattinson 

 went on to say that the fire, the effects of which they were considering,, 

 had burned a'considerable time before the explosion, and tlie evidence 

 showed that towards the base of the building, in what was called the- 

 vault. tliere were 47 tons of sul|ilinr spread out on the floor, over 

 which was placed a tarpaulin cover, and upon the top of the cover 

 there were placed 45 tons of nitrate of soda in bags. Now, his 

 opinion was that the sulphur in the vault took fire, which it would do- 

 at a temperature of 500 degrees or thereabouts. This would set fire 

 to the bags containing the nitrate, and some of the nitrate would be 

 melted, which, flowing over tbe burning Miliihur, would produce most 

 intense combustion, and this would, in a little time, extend itself to 

 all the sulphur and nitrate in the vault. The large quantity of these 

 substances thus deflagrating in a confined space woiUd necessarily 

 oenerate an intense heat, more intense, probably, than we could well 

 conceive, and if at this time water in sutKcient quantity should find 

 its way into the vault by any means, it would come in contact with 

 the highly incandescent "salts, when steam of resistless force would be 

 instantaneously generated, and tliis would occasion the explosion. 

 It had been "imagined that this explosion had been produced by 

 ei^ht tons of gunpowder, noboily imagining that more was required, 

 and nobody talking of any less ; but probably four tons of gunpowder 

 would produce the explosion. Now, to compare the force of steam 

 with that of gunpowder they had the following data :— Mr. Robins, 

 who experimented in guni)owdcr some years ago, found that 27 grains 

 of gunpowder, yielded an explosion of :H() cubic inches of per- 

 manently elastic gas, at which rate a grain of gunpowder would yield 



