I.] PRINCIPLES AND METHODS. 17 



books involving spectrum analysis which he or she- is likely to come 

 across ; terms such as 



Spectrum Fluted spectra 



Continuous spectrum Discontinuous (or selective) spectrum 



Grating Fraunliofer lines 



Prism Wave-length, wave-frequency 



Spectroscope Kadiation 



Slit Absorption 



Line spectra Series, 



should now have acquired a definite meaning, and I trust the expressive 

 ness of the terms will be acknowledged while they are accepted as part 

 of the future mental stock-in-trade. 



