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 required 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 increased 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 warlike propensities 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 Amoaful, 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 Review.
| RAIN-DROPS ON THE SEA. |
By Prof. 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
