238 GENERAL CONDITIONS OF SCIENTIFIC RESEARCH. 



discovered, and, in 1729, he gave his discovery to the 

 Royal Society. His paper is a very happy narrative of 

 his labours and his thoughts. His theory was so sound 

 that no astronomer ever contested it, and his observations 

 were so accurate that the quantity which he assigned as 

 the greatest amount of the change (one-ninetieth of a 

 degree) has hardly been corrected by more recent astro- 

 nomers.' ' When Bradley went to Greenwich as Astronomer 

 Royal, he continued with perseverance observations of the 

 same kind as those by which he detected aberration. The 

 result of this was another discovery, namely, the very 

 nutation (or slight oscillation in an elliptical orbit, of the 

 earth's axis) which he had formerly rejected.' l 



Similarly, it was whilst searching for certain changes 

 of temperature by passing an electric current through two 

 surfaces of mercury immersed in an alkaline solution of 

 double cyanide of mercury and potassium, I unexpectedly 

 discovered quite a different phenomenon, viz., that of 

 electrolytic vibrations and sounds. 



In other cases, acting upon the conviction that every 

 new experiment produces new results, even though they 

 may not be manifest, or of a kind we could predict, we 

 make a series of new experiments, hoping that amongst 

 the numerous new effects some may be conspicuous ; i.e., 

 we search for something new, we know not what, and we 

 find it. For instance, I once electrolysed a large variety 

 of metallic solutions, one of which was a mixture of ter- 

 chloride of antimony and hydrochloric acid, containing an 

 anode of antimony and a cathode of platinum. Having 

 obtained a thick deposit of the metal of bright steel-like 

 appearance, I attempted to remove it from the cathode, 

 when it suddenly shattered to small particles with evolution 



1 Whewell, Hisiory of Inductive Sciences, 3rd edit. vol. ii. p. 201. 



