596 



NA TURE 



[April 20, 1899 



does not seem open to doubt. I do not see how hydrod) naniic 

 laws enter into the question." 



Dr. Chessin writes : " With regard to Prof. Newcomb's 

 remark, I beg to observe that I did not raise the question as to 

 whether the law which Dr. See calls his (and which, more 

 correctly, should be called Hitter's, who expressed it in 1881, 

 as Dr. See states himself), was at all plausible or not. I simply 

 objected to Dr. See's Jerivalion, in the course of which, as I 

 have Slated before, he assumes that which he wants to prove. 



"As to neglecting the principles of hydrodynamics, it suffices 

 to point out, for example, the inadmissible assumption of uniform 

 density throughout a gaseous body in dynamical condition (v.l. 

 contraction and radiation)." 



SOURCES OF IMPORTANT MINERALS. 



AV.\LU.\BLE Blue Book by Prof. C. Le Neve Foster, 

 K.R.S., containing statistics relating 10 persons employed 

 in mining, the output of minerals, and the number of accidents 

 occurring in mines and quarries in the British Colonies and in 



I.— Diagr.im showing th 

 producing countri 



utput of coal i 



i (luring Ihe past twenly ye 



to yield its position to the younger branch of the Anglo-Saxon 

 race. The British Empire, as a whole, produces more than two- 

 fifths of all the coal raised in the world. 



Copper. — Figures do not furnish a proper basis for comparison 

 of output, because some countries state their output as ore, and 

 others as metallic cupper. The United States, with the enormous 

 output of 223,000 tons of metal, produce more than half the 

 copper of the world, and Spain and Portugal together about 

 one-eighth. 



Gold. — In the race of the gold-ptoducing countries the South 

 African Republic has been rapidly gaining upon the United 

 States, and, though a little behind in 1897, will take the first 

 place for the current year. In 1897 it maybe said approximately 

 that these two countries and .Australasia each produced more 

 than one-fifih of the world's supply. The only other country 

 needing mention is Russia, with nearly one-tenth of the total. 



Iron. — Tables which merely show tons of ore without stating 

 the average percentages of metal must be read with caution ; 

 but, whether judged by the gross weight of the ore or by the 

 actual amount of metal present, the United Slates take the lead 

 among the iron-yielding countries. Great Britain comes next 

 as a producer of iron, and is followed by Germany with its 10 



ihc principal coal- 



foreign countries, has just Ijcen published by the Home Office. 

 The tables are not complete, but the information given in them 

 presents many points of interest. The pari of the introduction 

 referring to output is printed below, and the two accompanying 

 diagrams, reproduced from plates in I'rof. Foster's report, illus- 

 trate graphically the variations in the production ol coal and 

 iron ore in several countries during the past twenty years. 



Coa/. — The United Kingdom is at present the most important 

 producer of coal, but the rapid growth of coal mining in various 

 parts of the United Stales, as apparent from the curve in dia- 

 gram (Fig. 1), and the knowledge of its enormous resources, 

 lead to the belief that the mother country will eventually have 



NO. 1538. VOL. 59] 



a. — Diagram 

 produc 



-ho»ing the 



[put of iron ore in the principal iron- 

 ■ing the past twenty years- 



million tons of ore derived mainly from the poorer but easily 

 wrought deposits of .\lsace- Lorraine. Spain ranks fourth with 

 a production of 7 million tons of ore; but in comparing its 

 position with that of Germany, the higher percent.tge of metal 

 in the Spanish ores should be borne in mind. In the same way 

 the low percentage of iron in the ore produced in Luxemburg 

 must be considered in comparing its output of 5 million tons 

 with that of France, Russia and Austria- Hungary. 



The proiiuction of iron ores in the principal countries during 

 the past twenty years is illustrated by a diagram (Fig. 2). 



Ifad. — Spain is the greatest lead-producing country in the 

 world ; it is followt<l at no great distance by the United States. 

 Germany produces little more than half the total output of 

 Spain. 



