370 PERSONAL PREPARATION FOR RESEARCH. 



asking in succession what effect will each have upon the 

 particular phenomenon. The following fragment of such 

 a table will show what I mean : What will be the effect 

 of gravity, pressure, motion, heat, light, electricity, mag- 

 netism, chemical affinity ; and of varying time of action, 

 direction, and strength of each of these ; also the effect of 

 conduction, radiation, refraction, reflection, and polari- 

 sation of heat upon it. And so on through all the chief 

 phenomena of all the forces of nature in succession ; and 

 also asking what will be the effect of different classes of 

 elementary substances, metals, metalloids, &c., and all the 

 separate elementary substances and their compounds in 

 succession. Instead of such a table, a copious index of 

 any good book on physical and chemical science may be 

 employed for the purpose. In this way even a student of 

 science may suggest a large number of new questions 

 respecting any phenomenon. Having obtained a collection 

 of new ideas and hypotheses in this way, the investigator 

 can proceed no farther without experiment, because hypo- 

 theses are unverified ideas and may be true or untrue, 

 and those which are true can only be found by actual 

 trial or observation. ' To the solid ground of nature, 

 trusts the mind that builds for all.' Schonbein made 

 ozone the study of his life ; but as he did not make suffi- 

 ciently numerous experiments upon that substance, it is 

 not to him so much as to other investigators that we are 

 chiefly indebted for our knowledge respecting it. 



New hypothetical questions having been suggested, it 

 is of service to write them out in the clearest form, and 

 make sketches of their anticipated operation and effects, 

 for in the absence of the actual object no man can so 

 vividly realise and perfect his ideas as when they are put 

 upon paper. Writing also enables a man to fix his mind 

 more strongly and continuously on a subject, and to carry 



