440 A SHORT HISTORY OF SCIENCE 



war and in peace. Its effects upon society and civilization have been 

 profound, and with society and civilization the progress of science 

 is always closely bound up. 



The manufacture of gunpowder marks the beginning of the manu- 

 facture of power, if we may describe the controlled accumulation, 

 storage and liberation of energy by that convenient term. In 1845 

 gun-cotton was invented by Schonbein, and in 1847 nitroglycerine by 

 Sobrero, and both explosives were found to be far more copious and 

 powerful sources of energy than gunpowder. It was Alfred Nobel, 

 however, a Swedish engineer, who after mixing nitroglycerine with 

 gunpowder first made practical use of this for blasting. It was also 

 Nobel who in 1867 made nitroglycerine less dangerous by diluting it 

 with inert substances such as silicious earth, mixtures to which he 

 gave the name dynamite. 1 



The manufacture of power from gravitational sources, such as 

 water-power and wind power, goes back to the earliest times 

 sails, wind-mills and water-wheels being of very ancient origin. 

 Power from fuel begins with Newcomen, Watt and the steam- 

 engine. Electrical power is at present chiefly derived indirectly 

 from gravitational (hydraulic) or from chemical (fuel) sources. 



THE STEAM-ENGINE. The last half of the eighteenth century was 

 not merely an era of great revolutions : it was also an age of great 

 inventions and among these, first in importance as well as first to 

 arise, was the steam-engine. 



Various and more or less successful attempts to utilize heat or 

 steam as a source of power had been made before Watt's time, such, 

 for example, as those of Hero in Alexandria (120 B.C.) the Marquis 

 of Worcester (1663) and Newcomen (1705). Of these only New- 

 comen's need be dwelt upon here. In Newcomen's engine a vertical 

 cylinder with piston was used, the piston-rod, also vertical, being fixed 

 above to one end of a walking-beam of which the other end carried a 

 parallel rod. Thus the rise and fall of the piston caused a corre- 

 sponding fall and rise of a parallel rod, which could be attached to 

 anything, e.g. to a pump. The cylinder was connected with a steam 



1 Nobel died in 1896, bequeathing his fortune, estimated at $9,000,000, to the 

 founding of a fund which supports the international "prizes" usually $40,000 

 each which bear his name and are annually awarded to those who have most 

 contributed to "the good of humanity." Five prizes have been usually given: 

 viz. one in physics, one in chemistry, one in medicine or physiology, one in 

 literature and one for the promotion of peace. 



