METEOROLOGY. 389 



to elucidate the connection between the sun- spots and rainfall by a 

 study of the hydraulics and physics of tbe Mississippi Kiver, as giveu 

 in the work of Humphreys and Abbot, together with more recent data, 

 and offers the following conclusions : From the observed discharge of 

 the Mississippi since 1819 there follows neither a confirmation nor a 

 refutal of Meldrum's law, according to which there should be heavier 

 rainfall at the time of the sun-spot maxima and slight rainfall at the 

 time of the minima. On the other hand, from the magnitude and ir- 

 regularity of the variations in the discharge compared with the period- 

 ical influence which in favorable cases should have been expected 

 according to Meldrum's law, we may safely conclude that in the Missis- 

 sippi watershed influences of this regular form are completely obscured 

 by the incomparably greater effect of apparently irregular variations 

 of wind and weather. If, however, this is our result for the Mississippi 

 in spite of the magnitude of the area represented by it and in spite of the 

 relative simplicity in the form of the North Americancontinent, then it 

 follows that a comiiensation of the disturbing influences by the accumu- 

 lation of a larger number of observations from all parts of the earth is in 

 general not probable and that it is therefore to be recommended that 

 the further investigation of the subject be based not upon an empirical 

 accumulation of observations but rather upon a more careful, intelligent 

 selection. In'this selection the principal circumstances to be attended 

 to are as follows: A constant direction of the wind through a whole 

 year or at least during the greater part of the year; when possible, such 

 a position of the area of observation that this wind shall be from the 

 ocean ; the greatest imaginable simplicity of topographic contour. If 

 from the observations that have so far been discussed we separate those 

 that correspond to this point of view, then from them almost without 

 exception can be deduced a confirmation of Meldrum's law. 



If we go still further and inquire into the possible reason of the paral- 

 lelism between sun-spot frequency and precipitation, or, what is almost 

 the same, between sun-spot activity and radiation of solar heat, it would 

 then appear as if a comparison of sun-spot phenomena with the period- 

 ical geyser eruptions would give not only a credible answer to this ques- 

 tion, but also would be proper to give information on many other prob- 

 lematic phenomena observed on the sun-spots. According to the results 

 of these comparisons the sun spots are nothing else than the external 

 evidences of the peculiar process of cooling on the sun, which goes on 

 in such a way that hot masses periodically come from the interior to the 

 surface, and in this way the loss of heat caused by radiation must from 

 time to time be always renewed ; and in this way these comparisons ac- 

 quire still another special interest, for they appear to present a solution 

 of the problem of the conservation of solar energy that leaves nothing 

 to be desired in the way of simplicity, of course with the important res- 

 ervation that this conservation of energy can only be a temporary state 

 of transition. {Z. 0. G. M., xix, p. 1.) 



