214 GENERAL CONDITIONS OF SCIENTIFIC RESEARCH. 



statical and Wilde's dynamical electric machine ; also in 

 the microphone. In some cases, however, our means of 

 detecting effects are more refined than our manipulation ; 

 for instance, it is almost impossible to obtain two large 

 pieces of metal (even of platinum), so perfectly prepared in 

 a similar manner, that on connecting them with a good 

 galvanometer and immersing them in a strongly acid con- 

 ducting solution, no deflection of the needles is observable. . 



In many cases we omit to employ the right method 

 of discovery, and in others where we have employed it, 

 we fail from various causes to observe a great number 

 of effects ; either because our faculties are unsuitable* in 

 kind or degree, or because the instruments or appliances 

 we use are insufficiently delicate, or because some of the 

 means employed for producing the effect are not sufficiently 

 powerful, or have not been properly balanced or arranged. 



The darkness of the undiscovered realm of future know- 

 ledge is so great, that the most discerning intellects have 

 in various cases missed important truths which lay close 

 to them. Gralvani missed chemical electricity, which Volta 

 soon afterwards discovered. Many eminent scientific in- 

 vestigators missed discovering the composition of the sun, 

 which Kirchoff and Bunsen found. Kepler about the year 

 1604, attempted, but failed to discover, the law of refrac- 

 tion of light. ' When we consider how simple the law of 

 refraction is, it appears strange that a person attempting 

 to discover it, and drawing triangles for the purpose, 

 should fail ; but this lot of missing what afterwards seems 

 to have been obvious, is a common one in the pursuit of 

 truth. The person who first did discover the Law of the 

 Sines was Willebrod Snell, about 1621 ; but the law was 

 first published by Descartes, who had seen Snell's papers.' 1 



1 Whewell, History of tlie Inductive Sciences, 3rd edit. vol. ii. 

 p. 276. 



