VI ADVERTISEMENT. 



Pure Mathematics specially applicable to the Observing 

 Sciences. The foundations for treatises on Electricity, 

 Tides, and Waves, exist in articles in the Encyclopaedia 

 Metropolitana ; and I trust that some Resident Mem- 

 ber of the University may be induced to exhibit these 

 branches of science in a form adapted to University 

 Education. In redemption of the engagement into 

 which I had virtually entered to place the other sub- 

 jects before the University, I have published works 

 on Probabilities and on Partial Differential Equations 

 (both with express reference to Mathematical Physics), 

 and on Sound. I now close my part of the undertaking 

 by this Treatise on Magnetism. 



I am indebted to James Glaisher, Esq. F.R.S. and 

 F.R.A.S., and to James Carpenter, Esq. F.R.A.S., of 

 the Royal Observatory, for much assistance in the 

 preparation of the diagrams inserted in the pages of 

 this work. 



G. B. AIRY, 



ROYAL OBSEKVATOBY, GREENWICH;,. 

 1870, November. 



