242 PERSONAL PREPAEATION FOR RESEARCH. 



strained to a high degree in conceiving new hypotheses 

 and devising means of testing them ; and the logical or 

 reasoning power is continually employed in explaining 

 phenomena and in tracing connections between them. 

 Some investigators are great in making experiments or 

 observations, others in raising hypotheses, some in success- 

 fully predicting new results, and so on. Priestley made a 

 great number of experiments. Tycho-Brahe made an im- 

 mense number of accurate observations ; Kepler was full 

 of wild and fanciful hypotheses ; Sir J. Herschel was un- 

 usually successful in predicting important new results. In 

 some scientific discoverers the logical and not the mathe- 

 matical faculty is largely developed; Faraday was an 

 example of this ; in others, both are combined. The most 

 common defects in scientific investigators are want of 

 perseverance and industry in experiments, and deficient 

 ability in discerning true explanations. As there is no 

 royal road to learning, neither is there an easy path to 

 the discovery of .great scientific truths. It needs a much 

 greater degree of mental power to discover new scientific 

 knowledge than to acquire and communicate that which is 

 known. 



Clearness of ideas is one great condition of success in 

 scientific discovery, but the ideas must not only be clear 

 but also be suitable. 'The operations of the mind as 

 well as the information of the senses, ideas as well as 

 facts, are requisite for the attainment of any knowledge ; 

 and all great discoveries in science require a peculiar 

 distinctness and vividness of thought in the discoverer. 

 This it is difficult to exemplify in any better way than 

 by the discoverers themselves. Both Davy and Faraday 

 possessed this vividness of mind ; and it was a consequence 

 of this endowment that Davy's lectures upon chemistry, 

 and Faraday's upon almost any subject of physical philo- 



