APPENDIX 



FURTHER EXAMPLES OF DISCOVERIES 

 IN WHICH CHANCE PLAYED A PART 



(i) It was not a physicist but a physiologist, Luigi Galvani, 

 who discovered current electricity. He had dissected a frog and 

 left it on a table near an electrical machine. When Galvani left 

 it for a moment someone else touched the nerves of the leg with 

 a scalpel and noticed this caused the leg muscles to contract. A 

 third person noticed that the action was excited when there was 

 a spark from the electric machine. When Galvani's attention was 

 drawn to this strange phenomenon he excitedly investigated it and 

 followed it up to discover current electricity. ^^^ 



(2) In 1822 the Danish physicist, Oersted, at the end of a 

 lecture happened to bring a wire, joined at its two extremities 

 to a voltaic cell, to a position above and parallel to a magnetic 

 needle. At first he had purposely held the wire perpendicular 

 to the needle but nothing happened, but when by chance he 

 held the wire horizontally and parallel to the needle he was 

 astonished to see the needle change position. With quick insight 

 he reversed the current and found that the needle deviated in 

 the opposite direction. Thus by mere chance the relationship 

 between electricity and magnetism was discovered and the path 

 opened for the invention by Faraday of the electric dynamo. 

 It was when telling of this that Pasteur made his famous remark : 

 " In the field of observation chance favours only the prepared 

 mind." Modem civilisation perhaps owes more to the discovery 

 of electro-magnetic induction than to any other single 

 discovery. ^^ 



(3) When von Rontgen discovered X-rays he was experiment- 

 ing with electrical discharges in high vacua and using barium 

 platinocyanide with the object of detecting invisible rays, but 

 had no thought of such rays being able to penetrate opaque 

 materials. Quite by chance he noticed that barium platino- 



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