IXTRODTCTION. 33 



nil branches of natural science are not equally important in 

 relation to general cultivation and industrial progress. An 

 arbitrary distinction is frequently made between the various 

 degrees of importance appertaining to mathematical sciences, 

 to the study of organised beings, the knowledge of electro- 

 magnetism, and investigations of the general properties of 

 matter in its different conditions of molecular aggregation ; 

 and it is not uncommon presumptuously to affix a supposed 

 stigma upon researches of this nature, by terming them 

 " purely theoretical," forgetting, although the fact has been 

 long attested, that in the observation of a phenomenon, which 

 at first sight appears to be wholly isolated, may be concealed 

 the germ of a great discovery. When Aloysio Galvani 

 first stimulated the nervous fibre by the accidental contact of 

 two heterogeneous metals, his contemporaries could never have 

 anticipated, that the action of the voltaic pile would discover 

 to us, in the alkalies, metals of a silvery lustre, so light as to 

 swim on water, and eminently inflammable ; or that it w r ould 

 become a powerful instrument of chemical analysis, and at 

 the same time a thermoscope, and a magnet. When Huyghens 

 first observed, in 1678, the phenomenon of the polarization of 

 light, exhibited in the difference between the two rays into 

 which a pencil of light divides itself in passing through a 

 doubly refracting crystal, it could not have been foreseen, 

 that a century and a half later the great philosopher, Arago, 

 would by his discovery of chromatic polarization, be led to 

 discern, by means of a small fragment of Iceland spar, whether 

 solar light emanates from a solid body, or a gaseous covering ; 

 or whether comets transmit light directly, or merelv by re. 

 flection.* 



An equal appreciation of all branches of the mathematical, 

 physical and natural sciences, is a special requirement of the 

 present age, in which the material wealth and the growing 

 prosperity of nations are principally based upon a more en- 

 lightened employment of the products and forces of nature. 

 The most superficial glance at the present condition of Europe 

 shows that a diminution, or even a total annihilation of 

 national prosperity, must be the award of those states who 



* Arago's Discoveries in the year 1811. Delambre's Histoin 

 p. 652. (Passage already quoted.) 



