732 THE POPULAR SCIENCE MONTHLY. 



ing-powder to a greater extent than it has accelerated that of powder 

 specially manufactured for military purposes. 



The following figures will give an idea of the amount of gun- 

 powder employed in mining operations : It is estimated that in coal- 

 mines about 80 pounds of powder are used for every thousand tons of 

 coal raised. In mines of lead and other minerals, which are found in 

 hard crystalline rocks, about 7,000 pounds of blasting-powder are re- 

 quired for every thousand tons of ore. To quarry a similar quantity 

 of sandstone 170 pounds would be used ; while for the harder granite 

 the amount would be 650 pounds. 



The quantity of gunpowder exported from England has not in- 

 creased very rapidly of late years. In 1860 it was 11,078,436 pounds, 

 of a declared value of 353,101. In 1865 it had risen to 16,833,723 

 pounds, valued at 457,078; and in 1870 it was 17,357,668 pounds, 

 valued at 427,229. The increase in weight, with a decrease in 

 value from 1865 to 1870, is due in a great measure to the fact 

 that we export an immense quantity of gunpowder of an inferior 

 quality to non-British ports in Western Africa ; and it is in this cheap 

 sort of gunpowder that the chief increase has taken place, while there 

 has been a falling off in the more valuable kinds. Thus, in 1870, 

 no less than 4,637,066 pounds, or more than 25 per cent, of the whole 

 export, went to Western Africa, chiefly to satisfy the Avarlike pro- 

 pensities of woolly-headed kings ; but it will be seen at once what the 

 quality of the powder was, when we add that its declared value was 

 only 83,657, while the comparatively small quantity of 1,173,762 

 pounds, exported to France, was worth 75,522, or about four times 

 as much in proportion to its weight. Heavy as our loss was at Amo- 

 aful, it would have been much more severe if the Ashantees had been 

 provided with something better than this worthless powder. As it 

 was, several of the men in the front line were struck five or six times 

 without being wounded, the bullets having such little force that they 

 fell harmlessly to the ground. Popular Science Heview. 



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BAIN-DROPS ON THE SEA. 



By Peof. OSBORNE REYNOLDS, M. A. 



THERE appears to be a very general belief among sailors that 

 rain tends to calm the sea, or, as I have often heard it expressed, 

 that rain soon knocks down the sea. Without attaching very much 

 weight to this general impression, my object in this paper is to point 

 out an effect of rain on falling into water which I believe has not been 

 hitherto noticed, and which would certainly tend to destroy any wave- 

 motion there might be in the water. When a drop of rain falls on to 



