54 ON MATTER, FORCE, AND MOTION IN SPACE. 



universe to another, we do but give scanty description 

 of the functions it is required to fulfil. The beam of 

 solar light thus translated by a series of pulses rapid 

 beyond conception in time and sequence, is in itself 

 the most wonderful of compounds. Newton, full of 

 the discovery he had just accomplished of the solar 

 spectrum, quaintly describes it as ' the oddest, if not 

 the most considerable, detection which hath hitherto 

 been made in the operations of nature/ The more 

 perfect analysis of this spectrum, now attained, has 

 disclosed to us not solely the different physical pro- 

 perties of the vibrations producing the different colours, 

 but also those invisible rays which by their respective 

 refrangibilities evolve heat and chemical power these 

 latter actions attaining their maximum respectively 

 beyond the opposite extremities of the luminous spec- 

 trum. Then came the further complexity of those 

 numerous dark lines in this luminous portion, from 

 which was inferred the non-emission of waves of colour 

 corresponding to these lines a naked inference now 

 clothed with a positive cause. But the knowledge of 

 the cause thus acquired, marking one of the most 

 extraordinary steps in physical science, does in nowise 

 lessen the wonder of these great natural phenomena. 

 Putting aside the unsolved question as to the nature 

 of the primary propelling power (if we say it is the 

 sun we do but screen the difficulty) we have to look 

 to our ether as the sole conveyance for these multi- 

 tudinous waves, thus complex in their properties as 

 expressed by their various action on matter, but com- 

 plex also in the act and manner of their propagation, 



