Ixxiv 



faith in God which was the foundation of his character, and which bright- 

 ened his declining years and the closing scenes of his earthly life. His many 

 personal friends will retain his memory in their warm affection. Posterity 

 will know him mainly for having opened up new regions in our knowledge 

 of optical phenomena, and for having given a mighty impulse to science 

 during two-thirds of the nineteenth century. 



J. H. G. 



