Mount Weather Observatory 



443 



a series of minor or local gyrations in 

 different latitudes. We have shown in 

 a paper that three aspects of one com- 

 mon law of general motion are mathe- 

 matically competent to account for the 

 three typical drifts, within which the 

 local storms occur as secondary phe- 

 nomena. The solar energy pours forth 

 in several types of radiation, and these 

 are accompanied by various kinds of 

 surface phenomena which are subject to 

 our observation. Their interpretation 

 is to be made in terms of the general 

 solar action, and they are to be treated 

 as pulses or symptoms of the great oper- 

 ations inside the solar surface, whose 

 laws can be discovered only by inference 

 and mathematical analysis. The im- 

 mediate signs of the internal solar action 

 are the frequency of the occurrence of 

 the black spotted areas which vary from 

 year to year, the relative abundance of 

 the faculse and the fiocculi, the granu- 

 lations of the photosphere, the numeri- 

 cal frequency of the hydrogen and cal- 

 cium prominences which are projected 

 to considerable distances above the disk, 

 and in the form and extent of the solar 

 corona. We now know that the period 

 of rotation in different zones and the 

 frequency of all these phenomena vary 

 from year to year in at least three fun- 

 damental cycles, whose lengths are re- 

 spective!}' about thirty-five years, eleven 

 years, and three years. The records dis- 

 close two or three thirty-five-year cycles, 

 more than twenty eleven-year cycles, and 

 a great number of three-year cycles. 

 We have in hand the typical annual 

 curves of these in about all the phe- 

 nomena mentioned, and they certainly 

 constitute a single homogeneous system, 

 as they apparently ought to do, since 

 they are various kinds of registers of the 

 same solar action. 



Beyond the surface of the sun there 

 are several types of radiation which 

 transport the solar energy into distant 

 cosmical spaces. The most conspicuous 

 is the electro- magnetic radiation, whose 



energy is practically confined to wave 

 lengths from 0.35 ;j. to 2.50 //, of which 

 the waves up to 0.8 // are visible, while 

 all the others are invisible to the human 

 eye. The other waves, ultra violet and 

 infra red, are detected through appro- 

 priate physical observations, by photog- 

 raphy, bolometry, and by spectroscopy. 

 There are also generated at the surface 

 of the sun certain electrical radiations, 

 like the cathode rays in a vacuum tube 

 where positive and negative charges of 

 electricity are transported by ions into 

 space, and these are seen in the long 

 coronal streamers, possibly also in the 

 zodiacal light at the earth. There are 

 weighty reasons for thinking that the 

 sun, like the earth, though having a 

 very high interior temperature, yet sus- 

 tains a magnetic field which embraces 

 the earth in its operations. 



At the earth the effect of these solar 

 forces is registered by the changes ob- 

 served in the aurora and the magnetic 

 elements. The solar annual curve, which 

 is conspicuously found in the promi- 

 nences, is reproduced in the earth's mag- 

 netic field. It is also found in various 

 portions of the earth to reappear in the 

 barometric pressure and temperature, in 

 the rainfall and the intensity of storms. 

 This signifies that the changes in the 

 internal circulation of the sun reach 

 over to the earth and induce synchro- 

 nous changes in the circulation of our 

 atmosphere. The several impulses men- 

 tioned, whether solar or terrestrial, 

 throughout which this synchronism has 

 been traced, are merely symptoms of the 

 great cosmical circulation extending 

 from the sun out into space and involv- 

 ing the planets more or less vigorously. 

 The earth is near enough to the sun to 

 feel the changes of the solar circulation 

 in a very definite manner. There are 

 a few hundredths of an inch of annual 

 pressure involved and two or three de- 

 grees of temperature are concerned. 



When we consider that the annual 

 values are made up of a great number 



