The Conductors of the London and Edinburgh Philosophical Magazine 
have to acknowledge the editorial assistance rendered them by their friend 
Mr. Edward W. Bravley, F.L. S., F.G.S., Assoc. Inst. C. E., Correspond- 
ing Member of the Royal Geological Society of Cornwall and of the Philoso- 
phical Society of Basle, Hon. Mem. S. Afric. Inst.; Librarian to the Lon- 
don Institution, and Secretary to the Electrical Society. # 
