86 Intelligence and Miscellaneous Articles. 



dimensions are not too small when compared with the axial dimen- 

 sions. 



4. The total quantities of magnetism spread over each hyperbolic 

 thread are proportional to the squares of the tensions \ existing at 

 the extremity of each of these threads — which leads to the formula 



A(«*i + a-*i)-2=A 2 (ah—a-hy. 

 Lid 



Since finishing the investigation of which the above is a sum- 

 mary, I have undertaken some researches on magnets of very 

 diverse forms ; and I have found that the form of the threads in 

 which the law I=A (a h —a~ h ) is maintained changes with the 

 bounding curve of the magnets. 



It is precisely in the investigation of these lines (which I call 

 homomagnetic lines, and which, in the case of circles and ellipses, 

 are hyperbolas) that the explanation is to be found of those still 

 little- studied phenomena of distribution named influence of the 

 margins or the anrjles. — Comptes Meadus de X Academic des Sciences, 

 vol. lxxxi. pp. 1099, 1100. 



NOTE ON THE TEMPERATURE OF THE UPPER STRATA OF THE 

 ATMOSPHERE. BY D. MENDELEEF. 



A greaf number of atmospheric phenomena depend chiefly on 

 the difference of temperature of the strata of the air ; and so the 

 quest of the theoretic and empirical laws of the variations of tem- 

 perature with altitude has for a long time attracted the attention of 

 several savants. Nevertheless even the theory of this question is 

 still very imperfect. 



The theory of the variation of temperature in the atmospheric 

 strata rests on the supposition that the upper strata receive heat 

 only from the lowest stratum, which is heated by the earth ; the 

 upper ones, therefore, would be cooled in dilating in consequence of 

 diminution of pressure. Such a supposition contains implicitly 

 this other, that air is diathermanous. For this case Poisson has 

 demonstrated, between the final temperatures t Q and t x when the 

 pressure varies from H to H^*, the relation 



1 + at 



(I)-' 



(1) 



in which k is the ratio of two specific heats, 1*41. This formula, 

 resting on the mechanical theory of heat, and agreeing with expe- 

 riment, should, if the preceding hypothesis were accurate, be appli- 

 cable to the determination of the temperatures t 1 of the strata of 



* At first sight one might think that, in calculating the temperature of 

 the upper strata, we ought to take into account not merely the heat ex- 

 pended for the dilatation due to the diminution of the pressure, but also 

 that which is equivalent to the work of raising : the lowering of tempe- 

 rature would thus be doubled. This would be an error ; for at the same 

 time that a certain mass of air rises, another mass, equal to it, descends ; 

 otherwise equilibrium of the air would not take place : this is especially 

 apparent when we consider, as we do now-a-days, the molecules of gases 

 to possess a proper motion, the cause of diffusion &c. 



