7 88 THE POPULAR SCIENCE MONTHLY. 



that of any other leading commodity i. e., from 26 per flask (the 

 highest) on the London market, in 1874, to 5 2s. M. (lowest) in 1884 ; 

 and from $118 (highest) to $26 (lowest) on the San Francisco market 

 during the same period a decline of 77*1 per cent. The explanation 

 of this movement of price is to be found mainly in the circumstance 

 that California, which furnishes nearly one half of the world's supply 

 of this metal, increased her production from 30,077 flasks in 1870 to 

 79,684 in 1877 ; and although, as the result of low prices, only ten of 

 thirty working mines of California were in operation in 1885 (none of 

 which paid a dividend in that year), the generally increased supply of 

 quicksilver, coupled with its diminished use in the reduction of silver- 

 ores consequent on the introduction and use of cheaper pi'ocesscs 

 has thus far prevented any material augmentation in its price, the 

 London quotation for June, 1887, having been 6 15s. per flask. 



Silver. The annual supply of silver from the mines of the world 

 has largely increased since 1872-73, the period covered by the marked 

 decline in the market price of silver, or from $65,000,000 in 1872 to 

 $102,168,000 in 1881 ; $115,000,000 in 1883, and $124,000,000 in 1885 

 an increase in supply in fourteen years of 90'7 per cent.* 



Coal. The decline in the export prices of British coal, comparing 

 the average for 1867-'77 with 1886, was about 33 per cent. The de- 

 cline in the average annual price of anthracite coal (by the cargo at 

 Philadelphia), comparing 1870 with 1880, was 38 percent ; but, as be- 

 tween 1870 and 1886, it was only 6*6 per cent. The total production 

 of all kinds of coal in the United States in 1886, according to the re- 

 turns of the United States Geological Survey, shows a net gain of 

 1,785,000 short tons, as compared with 1885, but a loss in value at 

 the point of production of $4,419,420. 



The increase in the product of the five chief coal-producing coun- 

 tries of the world, Great Britain, the United States, Germany, France, 

 and Belgium, from 1870 to 1886 inclusive, has been in excess of 80 per 

 cent Great Britain increasing her product from 109,000,000 tons in 

 1870 to 159,351,000 in 1885 ; and the United States from 38,468,000 

 in 1870 to 112,743,000 short tons in 1886. On the other hand, the 

 amount of coal displaced from use in the United States in 1886 by the 

 introduction and use of natural gas is estimated by the United States 

 Geological Survey at 6,353,000 tons, valued at $9,847,000. In Germany, 

 the increase reported was from 36,041,000 tons in 1873 to 55,000,000 

 tons in 1883. In 1870 the average output of coal per miner in the 

 British coal-mines counting in all the men employed was 250 tons, 

 an amount never before reached. In 1879 this average had increased 

 to 280 tons per man, and in 1884 the average for the five preceding 

 years was reported at 322 tons, an increase of 42 gross tons of 21 cwt. 



* The estimates of the annual silver production of the world, submitted to the Royal 

 (British) Commission on Gold and Silver by Mr. Hector Hay, are somewhat smaller, 

 namely, 12.8 in 1873; 18.8 in 1881 ; 20.6 in 1883 ; and 21.3 in 1885. 



