The Evolution of the Sciences 



the study of eclipses is no longer carried out by 

 the telescope alone. All the instruments of the 

 physicist are brought to bear upon the sun at the 

 moment of occultation. And in addition to this 

 physical astronomy does not interest itself only 

 in the distant stars; it studies everything that is 

 beyond our direct reach the higher regions of 

 the atmosphere, the meteors which invade it, 

 the aurora borealis and the zodiacal light. 



This brief enumeration should suffice to 

 justify the right to existence of a new science, 

 connected with astronomy by its field and with 

 physics by its methods of study, but having its 

 own individuality and clearly-defined object. 



Physical chemistry, which is barely fifty 

 years old, may also claim a place among the 

 new sciences. It was brought into existence 

 in France through the labours of Sainte-Claire 

 Deville and Berthelot, but has developed chiefly 

 in Holland and in Germany, and has to-day a 

 definite aim, many established results, and a 

 vast field for future work. Chevreul held that 

 " the object of chemistry is to classify matter 

 into types, called chemical species, each 



characterised by a definite group of physical, 



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