428 Bigelov: — Meteorological Elements of the United States. 



The variations of the magnetic field should embrace several 

 stations in each hemisphere, and combine the horizontal 

 component with those of the declination and the vertical 

 force. The comparison of the direct and the inverse forms of 

 the adopted 26*68 day curve, which apparently lies underneath 

 the complex phenomena of circulation in the earth's atmos- 

 phere, should be carefully followed out in different regions, in 

 order to discover the least disturbed place for observatory - 

 work. The relation of this central or heart action to the other 

 members of the atmospheric system can then be studied out. 

 6. The many problems that I have not mentioned, but 

 which are implied in this series of relations, are most fascinat- 

 ing. Not the least of these is the possibility of developing a 

 system of long-range seasonal forecasting. When the crests on 

 the curves reach a certain amplitude, it is easy to foresee their 

 course for a couple of years. The fact that the terrestrial 

 curves tend to lag somewhat behind the solar curves make 

 this a point of value. Since the prominences on the sun 

 develop in middle latitudes a year sooner than they do near 

 the equator or near the poles, there is a chance here to 

 anticipate the impulse at the earth that moves the atmospheric 

 ..circulation. Our next study will be on the monthly and 

 seasonal variations, as distinguished from the annual variations 

 treated in this paper. It is important to secure homogeneous 

 data of the sun's prominences, the earth's magnetic field and 

 the temperatures, in places of quiet circulation, such as in 

 So. California, to serve as the basis for other corollary 

 researches. It has beeu assumed in this paper that the 

 frequency of the prominences and the amplitudes of the 

 magnetic field are practically proportional to the intensity of 

 the invisible solar radiation. There are no better elements 

 available at present, and until a continuous homogeneous series 

 of observations with the bolometer or the pyrheliometer are 

 secured, extending over many years, it will not be possible to 

 bring this problem to a conclusion. There will doubtless be a 

 difference of opinion as to the final interpretation of such data, 

 because the smallness of the residuals and the overpowering- 

 influence of the circulation in effacing the evidences of 

 synchronism, introduce an element of uncertainty. It must 

 be shown to what extent the maxima of the invisible radiation 

 coincide with the maxima of the prominences. Again, it is 

 evident that the apparent synchronism on the Pacific Coast 

 is partly destroyed through reversal and the turmoil of the 

 cyclones and anticyclones in the lower strata of the atmosphere. 

 It may properly be inferred that the stations for making 

 observations on radiation should be located in the midst of the 

 high pressure belt in about latitude 33°-35°, where the circu- 



