EXAMPLES OF UNEXPECTED DISCOVERIES. 235 



tative facts is usually the most unpredictable, and the 

 most unexpected discoveries in physics and chemistry are 

 generally those of rare substances or of isolated pheno- 

 mena of an entirely novel and peculiar kind ; the dis- 

 covery of a new elementary substance has rarely been 

 successfully predicted (for an exception to this latter state- 

 ment see pp. 232-3). 



A few discoveries are also made by persons engaged 

 in arts and manufactures, who occasionally, but much less 

 frequently, also observe matter and its forces under new 

 circumstances. Such discoveries are more truly matters 

 of accident, because those who make them are not search- 

 ing for new truths, and therefore find them more unex- 

 pectedly ; manufacturers also are rarely scientific investi- 

 gators. In arts and manufactures the processes are usually 

 upon a large scale, and this sometimes makes the new 

 effect conspicuous, and causes it to be observed. As an 

 instance of such c accidental ' discovery may be mentioned 

 the finding of the so-called ' hydro-electricity ' produced 

 by the friction of water and steam against the sides of a 

 pipe. The first fact of this kind was observed by a work- 

 man attending a steam-boiler at Newcastle, who found 

 that he received electric shocks if he touched the boiler 

 during the blowing off of the steam. The true cause of 

 the phenomenon, however, was discovered by Armstrong 

 and Faraday, who investigated the action. The static 

 electric charge acquired by insulated electric-telegraph 

 cables by contact with one end of a voltaic-battery was 

 also first observed by practical persons, and afterwards 

 scientifically investigated. Ingenious persons engaged in 

 developing improvements in arts and manufactures some- 

 times consider they are making discoveries when they are 

 really making inventions (i.e. applying known truths in a 

 new way to some useful purpose) simply because they have 



