50 Mr. Airy — Analysis of 177 Magnetic Storms. [Dec. 17, 



by montlis, but no certain conclusions follow. In Table XI. the Ware- 

 disturbances and the Irregularities are arranged by hours ; for the Wave- 

 disturbances results are obtained which may be compared with those of 

 previous investigators ; in Table XII. it is shown that these may be repre- 

 sented by a general tendency of wave-disturbances, different at different 

 hours, which general tendency is itself subject to considerable variations. 

 For the Irregularities it is found that the coefficient is largest in the hours 

 at which storms are most frequent. It does not appear that any sensible 

 correction is required to the Diurnal Inequalities of the former paper on 

 account of these disturbed days. 



The author then treats of the physical inference from these numerical 

 conclusions. And in the first place he states his strong opinion that it is 

 impossible to explain the disturbances by the supposition of definite 

 galvanic currents or definite magnets suddenly produced in any locality 

 whatever. The absolute want of simultaneity (especially in the Irregu- 

 larities), and the great difference of numbers between the Waves and Irregu- 

 larities for the Nadir Force (in which the Irregularities are just as strongly 

 marked as in the Westerly and Northerly, and the Wave-disturbances are 

 much more strongly marked), and those for the other Forces, appear fatal 

 to this. 



It is then suggested that the relations of the forces found from the 

 investigations above, bear a very close resemblance to what might be ex- 

 pected if we conceived a fluid (to which for facility of language the name 



Magnetic Ether " is given) in proximity to the earth, to be subject to 

 occasional currents produced by some action or cessation of action of the 

 sun, which currents are liable to interruptions or perversions of the same 

 kind as those in air and water. He shows that in air and in water the 

 general type of irregular disturbance is travelling circular forms, sometimes 

 with radial currents, but more frequently with tangential currents, some- 

 times with increase of vertical pressure in the centre, but more frequently 

 with decrease of vertical pressure; and in considering the phenomena 

 which such travelling forms would present to a being over whom they 

 travelled, he thinks that the magnetic phenomena would be in great 

 measure imitated. 



The author then remarks that observations at five or six observa- 

 tories, spread over a space less than the continent of Europe, would pro- 

 bably suffice to decide on these points. He would prefer self-registering 

 apparatus, provided that its zeros be duly checked by eye-observations, and 

 that the adjustments of light give sufficient strength to the traces to make 

 them visible in the most violent motions of the magnet. For primary 

 reduction he suggests the use of the method adopted in this paper, with 

 such small modifications as experience may suggest. 



