CONTINUITY. 197 



myself, were it not that I may be misunderstood and supposed 

 to have abandoned all claim to a share in the initiation of 

 this, as I believe, important generalisation) have carried on 

 the work ; and how, sometimes by independent and, as is 

 commonly the case, nearly simultaneous deductions, some- 

 times by progressive and accumulated discoveries, the doctrine 

 of the reciprocal interaction, of the quantitative relation, and 

 of the necessary dependence of all the forces, has, I think I may 

 venture to say, been established. 



If magnetism be, as it is proved to be, connected with the 

 other forces or affections of matter, if electrical currents 

 always produce, as they are proved to do, lines of magnetic 

 force at right angles to their lines of action, magnetism must 

 be cosmical, for where there is heat and light there is elec- 

 tricity, and consequently magnetism. Magnetism, then, must 

 be cosmical and not merely terrestrial. Could we trace 

 magnetism in other planets and suns as a force manifested in 

 axial or meridional lines, i.e. in lines cutting at right angles 

 the curves formed by their rotation round an axis, it would 

 be a great step ; but it is one hitherto unaccomplished. The 

 apparent coincidences between the maxima and minima of 

 solar spots, and the decennial or undecennial periods of ter- 

 restrial magnetic intensity, though only empirical at present, 

 might tend to lead us to a knowledge of the connection 

 we are seeking ; and Sir Edward Sabine considers that an 

 additional epoch of coincidence has arrived, making the 

 fourth decennial period ; but some doubt is thrown upon 

 these coincidences by the magnetic observations made at 

 Greenwich Observatory. In a paper published in the 'Trans- 

 actions of the Royal Society,' 1863, the Astronomer-Royal 

 says, speaking of results extending over seventeen years, 

 there is no appearance of decennial cycle in the recurrence of 

 great magnetic disturbances ; and Mr. Glaisher last year, in the 

 physical section of this Association, stated that after persever- 

 ing examination he had been unable to trace any connection 

 between the magnetism of the earth and the spots on the sun. 



Mr. Airy, however, in a more recent paper, suggests that 

 currents of magnetic force having reference to the solar hour 

 are detected, and seem to produce vortices or circular disturb- 



