Magnetical Ohsewatory of Dublin during the Years 1840-43. 



85 



Tlie following Table contains the computed values of these two functions, for 

 the several months of the year, the units being one minute of declination, 'one 

 degree of temperature, and one hour of time. 



Table VI. Areas of the diurnal curves of Declination and Temperature. 



For the purpose of comparison, the preceding numbers are graphically pro- 

 jected in Plate III. figs. 1 and 2, one division of the scale corresponding to four 

 minutes of decUnation, and to eight degrees of temperature. These curves ex- 

 hibit in the clearest manner the correspondence between the two classes of 

 phenomena, and leave no doubt whatever that they stand in the relation of 

 effect and cause. The slight dissimilarities which exist between them are 

 abvmdantly accounted for by the circumstance, that it is to the heating power 

 of the sun, exerted upon the earth's surface (and not upon its atmosphere), that 

 we must ascribe the changes of decUnation ; and I venture to predict, that as 

 soon as we are in possession of data respecting the diurnal changes of tempe- 

 rature of the earth's surface, sufficient for the purposes of a comparison such 

 as that now made, the agreement of the laws will be found to be stHl more 

 complete. 



The same agreement appears, also, upon a comparison of the mean yearly 

 values of the same functions, calculated for the four years ; the foUowmg are 

 the results. 



Table VII. Areas of the diurnal curves of Declination and Tesipeeaiure, fob 



THE separate VEARS. 



