SCIENTIFIC TEACHERS SHOULD BE INVESTIGATORS. 301 



spectrum independently of each other. Wollaston and 

 MM. Ritter and Beckman also discovered simultaneously the 

 ultra-violet, or invisible chemical rays of solar light. The 

 discovery of thallium by Crookes was soon afterwards 

 followed by the rediscovery of that substance by Lamy. 

 My explosive electro-deposited antimony has also been 

 several times rediscovered by different persons. 



In some cases, however, the possession of scientific 

 knowledge acts rather as a hindrance to original research, 

 by absorbing the mind in the acquisition and contempla- 

 tion of what is already known, instead of causing its 

 possessor to press onwards to the honour of discovering 

 new truths. This is conspicuously the case with scien- 

 tific students who have been taught by Professors who are 

 not themselves original investigators, and is lamentably 

 so to a large extent at our old Universities. In Germany, 

 however, where the teachers themselves possess the genius 

 of originality, and in those institutions in this country 

 where a similar condition exists, the students are en- 

 couraged in original work by their teachers, and thus ac- 

 quire the ability of making discoveries. 



It has also been remarked, that the possession of mathe- 

 matical knowledge has sometimes induced mathematicians 

 to abstain from making experiments, because their theories 

 appeared complete and not to include them ; and has 

 caused them to doubt the truth of the results of new 

 experiments made by others. It has also been said that 

 all the truths in electro-dynamics discovered by Faraday 

 might have easily been predicted mathematically from a 

 knowledge of Ampere's laws ; but it is a noteworthy fact, 

 that although that truth is now so palpable, it was not 

 manifest to the greatest mathematicians at the time, 

 because no one predicted these effects, nor stated that 

 truth until after the effects were obtained ; and this is in 



