NOTES. 421 



trial development. According to the United States Treasury 

 Statistical Bureau's Summary, the world's production of coal 

 rose from 144 million tons in i860 to 450 million tons in 1883, 

 and to 866 million tons in 1901, an increase in 40 years of 

 over 500 per cent, and since 1820, when coal was first more 

 generally recognized as fuel, the increase has been 4500 per 

 cent. Five-sixths of the present consumption was furnished 

 for the last 30 years by Great Britain and Germany, and 

 Belgium, the largest consumer of coal per capita after Great 

 Britain. The coal production of the United States, which 

 in 1870 furnished but 15 per cent of the world's supply, 

 has grown steadily until in 1901 it represented, with 295 

 million tons, 34 per cent, outstripping Great Britain and 

 Germany. 



What the substitution of coal for fuel means may be realized 

 by translating the coal consumption into wood consumption. 

 The fuel value of a ton of coal may be set equal to about loo 

 cubic feet of wood; hence the 170 million tons of coal now 

 consumed per annum in the United States supplant 17 billion 

 cubic feet of wood. To raise this amount of wood continu- 

 ously not less than 300 million acres, more than half our pres- 

 ent acreage (at 56 cubic feet per acre), would have to be kept 

 under good forestry management. 



P. 27. Cellulose and Wood Pulp Industry. — Wood pulp is 

 either mechanically ground or chemically prepared, when it is 

 called cellulose, or chemical fibre. Most of it is used for the 

 manufacture of paper. The progress of the wood pulp indus- 

 try in the United States has been marvellous, as shown by the 

 growth in daily capacity of running wood pulp mills. 



While in 1 88 1 this was less than 800,000 lbs., it .had more 

 than doubled in 1887, and again more than doubled within 

 two years in 1889, increasing steadily fi-om that time. 



The following figures, taken from Lockwood's Paper Trade 

 Journal, include both mechanical pulp and chemical fibre, but 

 do not take into account small amounts produced by paper 

 mills directly : — 



