THEORIES AND MODELS 253 



sirous of warping my numbers according to an atomic theory, but 

 have endeavored to make practical convenience my sole guide, . . . 



Renouncing all speculation about "purely theoretical" entities, Wol- 

 laston sought only an economic description of observables. And, in- 

 deed, if Wollaston is today at all remembered as a chemist, it is as 

 the inventor of the chemical slide rule: a practically useful calcu- 

 lational device, and nothing more. Compare the meagre harvest 

 achieved by Wollaston's caution with the abundant fruits of the 

 daring of Dalton, Avogadro, Berzelius, and a host of others. Surely 

 one can generalize to all fields of science the conclusion Born puts 

 thus: 



All great discoveries in experimental physics have been due to the 

 intuition of men who made free use of models, which were for them 

 not products of the imagination, but representatives of real things. 



