252 EXPLOSIVES : MANUFACTURE AND USE. 



attended with the happiest results. True, much still remains to 

 be done, but the researches to which I have referred have indi- 

 cated one line of improvement. Even to those who don't know 

 much about mining or the use of explosives the mortality on 

 the mines must always have appeared very great, and a large 

 proportion of these always figured under the heading " gas- 

 sing." Gassing is caused by the inhaling of either carbon 

 monoxide or nitric peroxide, or both, but more frequently the 

 former. Now theoretically neither of these ought even to be 

 produced, but in practice, as was found out during the course 

 of the experiments, the former is always formed, and that 

 in dangerous quantities. The samples of gas for the examina- 

 tion were obtained in rather an extraordinary manner. I pass 

 over the difficulties which had to be overcome in 

 arriving at a satisfactory method of determining with accuracy 

 the small quantities of carbon monoxide which had to be taken 

 account of, and will only state that an explosive has been dis- 

 covered which produces very little indeed, and this apparently 

 so safe that some miners have actually the hardihood to return 

 to the face immediately after a large blast. This is not a prac- 

 tice which I should recommend, but that it has been possible 

 to do so is the strongest evidence of the importance of the 

 discovery — and one which I am pleased to say has been made 

 in a South African laboratory. The improvement which will 

 be effected in the state of the underground atmosphere when 

 this explosive comes into general use, together with the im- 

 proved systems of ventilation, will cause a revolution in mining 

 and a great improvement of the health of the miners. 



I am aware that this lecture is extremely elementary. Neither 

 it nor the slides please me, but both have been prepared under 

 the greatest pressure of work, and this must be my excuse. I 

 can only hope that it has interested you in a subject which is 

 not brought often before the public, and that you have now a 

 somewhat better understanding of the vastness of the subject. 



A HALLEY COMMEMORATION The fact that Halley 



occupied the Savilian chair of astronomy at Oxford, says 

 Nature, gives this University a special interest in Halley's 

 comet. This interest the University proposes to mark by con- 

 ferring the honorary degree of Doctor of Science on Mr. P. 

 H. Cowell, F.R.S., chief assistant, and Mr. A. C. D. Crom- 

 melin, assistant, at the Royal Observatory, Greenwich, by 

 whose joint calculations the exact determination of the re- 

 appearance of Halley's comet was successfully accomplished. 

 The actual ceremony of conferring the degree will probably 

 take place in May, at the time when the comet is expected to 

 be at its brightest. It has further been arranged that the first 

 discourse given on the new foundation of the Halley lecture 

 shall be delivered by the founder himself, Dr. Henry Wilde, 

 F.R.S., and it is hoped that this may take place at the same 

 time as th-e conferring of degrees on the two Greenwich 

 astronomers. 



