462 F. H. Bigelow — Solar and Terrestrial Magnetism. 



seated in the unsteady sun for a base, we must expect to deal 

 with just such fluttering curves as are herein described. At 

 least my interpretation of the many hundred curves reduced to 

 the 26*68 day period, is worthy of careful consideration. 



It will be noticed that I terminated my discussion of the 

 cause of the phenomenon, and the pure physics involved in 

 the inversion of the type curve, rather abruptly, after showing 

 its relations to the magnetic field of the sun in the several 

 parts of the orbit. It is clear that the components are such as 

 to produce opposite effects, the held lying now across and 

 again along the orbit, the earth driving through it at the rate 

 of a million miles a day. After long consideration of the com- 

 plicated conditions involved, the three axial motions and the 

 complex computations required, the lack of our knowledge 

 about atmospheric transformations of energy and radiations, I 

 conclude that the problem is beyond my powers for the time 

 being. This is also the more the case because of the total lack 

 of magnetic observations in the northwest of the United 

 States and western Canada, upon which to do definite work. 

 The European data are good, but Europe is too far away, and 

 unfortunately it is located in the hollow of the external field, 

 belt M, Chart 10, where the exflected and inflected branches 

 come together, and where the forces are very fluctuating in 

 their directions. To make matters worse, just at this time our 

 American observations have been practically extinguished by 

 the encroachments of the city electric trolley lines, and the 

 material is now rendered useless for these refined purposes. 

 The only alternative seems to be to remove the observatories 

 far into the country, to some spot away from the advance of 

 the improvements of civilization. However, in view of the 

 unusual interest and importance of the material contained in 

 Bulletin No. 21, even if only a portion of it sustains final 

 criticism, it is evident that the duty of American Science is to 

 set up some first class magnetic observatories, and to run them 

 for a term of years, till we can get good data to work upon in 

 the pure physics required. It is hoped that this paper will be 

 considered a valid plea to bring this about before very long. 



