WILHELM HITTORF AND WILLIAM CROOKES 345 



this cathode: the 'cathode rays' discovered by Hittorf. 

 Hittorf was ten years ahead of Crookes in this investigation. 

 But Crookes was able to follow the way thus indicated as 

 the first, and for the time, only understanding mind after 

 Hittorf,^ and he was able to obtain better and newer ex- 

 perimental apparatus, in particular air pumps and other 

 technical assistance. He showed his power of understanding 

 by making very great further progress in the direction of 

 solving the peculiar character of the phenomena of radia- 

 tion, so that from this point enough was known to lead in- 

 vestigators of nature almost irresistibly in a certain direction, 

 namely to the pure observation of these rays. Out of this 

 hardly less actually developed - although a further fifteen 

 years were required for the purpose - than Crookes had 

 promised when he said: 'Here we shall find ultimate truth.' 

 Crookes and Hittorf were in every respect excellent com- 

 plements of one another in this fundamental research. 

 While Hittorf was very careful not to go beyond facts for 

 which he could vouch with certainty, Crookes opened up 

 vistas with the joy of the discoverer, and communicated this 

 joy to others. Although many of his views were erroneous, 

 his faith in the richness of nature was justified, and, holding 

 it so strongly, he was able to induce successors gifted with 

 equal confidence and ability to take the correct direction 

 with complete certainty, when they set out on their dis- 

 coveries. Hittorf's publications were dry, and almost re- 

 pulsive; their great value was buried in the depths. Crookes 

 announced with enthusiasm what he observed; but he had 

 in England the best opportunity for doing so.^ 



^ There had been many observers of discharge phenomena before and 

 after Hittorf; it was a field of work which easily led to descriptions without 

 end of what had been seen. But all these descriptions only led, in the 

 best case, to real new knowledge, when that lacking in them all, namely 

 the attempt to reach understanding by means of clearly devised experi- 

 ments, had been supplied from another side. 



2 Hittorf published his lesults 'On the conduction of electricity by 

 gases' in Poggendorf's Annalen, Vol. 136, 1869. Crookes gave in 1879 



