APPENDIX I: INVENTIONS 439 



sometimes show no discoverable resemblance to their immediate 

 forbears, so inventions may come without disclosing any resemblance 

 to parent inventions or ideas, while yet really intimately related to 

 knowledge that has gone before. 



Nor is it easy to estimate the reciprocal debt of science to inventions 

 and the arts. That this debt is large there can be no doubt. To 

 illustrate this fact it is hardly necessary to do more than mention 

 examples, such as the service of the compass to the sciences of geog- 

 raphy, navigation and surveying ; -of the telescope and the chronom- 

 eter to astronomy ; of the microscope to biology ; of the air pump 

 to natural philosophy ; or of the abacus or the Arabic numerals to 

 arithmetic. 



Among the more notable of the inventions of the nineteenth cen- 

 tury were the locomotive, the steamboat, the friction match, the 

 sewing-machine, the steel pen, the telegraph, the telephone and the 

 phonograph ; labor-saving machinery ; explosives ; and the internal 

 combustion engine, with its numerous offspring (motor vehicles, air- 

 planes, motor boats, etc.). 



POWER : ITS SOURCES AND SIGNIFICANCE. The recent progress 

 of science and of civilization has been accompanied by a remarkable 

 extension of man's control over his environment, which has come 

 largely with his ability to develop, transmit, and utilize chemical, 

 gravitational and electrical energy or power^. The ancients and the 

 men of the Middle Ages used chiefly the power of man and other ani- 

 mals and of winds (windmills) and to some extent water (i.e. gravi- 

 tation), as in water-wheels, but knew little of heat power or chemical 

 power and nothing of electrical power, or of power transmission of 

 any kind, except in moving herds, treadmills, or marching armies. 



In past times the chief store of national power was manual labor : to-day 

 it is the machine that does the work. K. Pearson. 



The first step in the modern direction was apparently toward chemi- 

 cal power, in the invention of gunpowder. 



GUNPOWDER, NITROGLYCERINE, DYNAMITE. Gunpowder is be- 

 lieved to have been known to the Chinese long belong it appeared 

 in Europe. An explosive mixture of charcoal, sulphur, and nitre 

 was apparently also known to the Arabians, but the first important 

 appearance of gunpowder in Europe was about the fourteenth cen- 

 tury, and since the sixteenth it has played an all-important part in 



