of electricity on a useful scale, made possible by the in- 

 vention of the dynamo by Faraday (c. 1830), led to the 

 release of a new force to aid human effort unequalled in 

 its usefulness even today. Faraday made many other signifi- 

 cant contributions to physics and chemistry, including dis- 

 coveries bearing on the structure of matter and the nature 

 of electric and magnetic fields of action. Using Faraday's 

 results, Maxwell (1873) postulated the existence of radio 

 waves which were later produced experimentally by Hertz 

 (1887). Dalton (1803) first explained the known laws of 

 chemical combination of the elements in terms of an atomic 

 theory, and Hutton (1785) concluded from his observa- 

 tions of the Earth's rock strata that our planet must be tre- 

 mendously old — a conclusion confirmed by Rutherford (c. 

 1910) during his studies of radioactivity. Steel was made 

 on a large scale by Bessemer about 1850 — the start of our 

 modern age of materials. And in 1859 Darwin declared 

 his conclusions on the fundamental process of evolution of 

 living organisms — the most important discovery ever made 

 in the field of biology — and so greatly strengthened the 

 position of science with a consequent weakening of the 

 position of religion in human affairs. The actual laws of 

 biological inheritance were discovered experimentally by 

 Mendel in 1865, and with the microscopic observ^ation of 

 the detailed processes of cell division, involving the dis- 

 covery of the chromosomes and genes within the cell, in 

 the first decades of the twentieth century, Darwin's ideas 

 received strong confirmation. The further study of electri- 

 city in the latter half of the nineteenth century led to the 

 discovery of the free electron by Thomson (1897) — one of 

 the fundamental particles composing all matter — and then 

 in rapid succession the discovery of X-rays (Rontgen, 

 1895), and of radioactivity (Becquerel, 1896). 



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