and other Spectra with the Spectrum of the Aurora. 261 



Table showing comparative position of Aurora-lines with prin- 

 cipal lines in the examined spectra. C means coincident within 

 the limits of my instrument and scale, N near, and V N very 

 near. 



Conclusions. 

 I intended to conclude the preceding observations with a 



o 



few remarks on Professor Angstrom's propositions, for the pur- 

 pose of discussing how far the latter seemed in accord with the 

 above experiments. My attention, however, has been called to 

 an extract from a letter written by Professor A. S. Herschel to 

 It. H. Scott, Esq., and printed in the Philosophical Magazine 



for January 1875, in which Professor Angstrom's memoir is 

 also reviewed and discussed. 



I propose to have this letter in view while drawing some conclu- 

 sions from my own observations ; and in the outset I candidly 

 confess I hesitate to indorse Professor's Herschel's axiom, that 



o 



Professor Angstrom's memoir is " conclusive and satisfactory," 

 and that " little more will be done now by future observers than 

 to verify his conclusions and extend their researches in the direc- 

 tion he points out." 



