1881.] ^'5 [Chase, 



This represents a thermal energy of 990.7 X 5380 -v- 1389.6 = 3764.32 cal- 

 ories, which would be communicated by a temperature of 3764°. 32 C, or 

 6775^.78 F. The temperature of melting rock is estimated by Sir William 

 Thomson (Thomson and Tait's Natural Philosophy, i, App. D., p. 716) 

 at 7000° F. Notwithstanding the crudeness of this approximation, it 

 shows that the temperature which represents orbital reactions against 

 sethereal stress is of the same order of ma'gnitude as that of melted rock, 

 thus corroborating other evidence of the probable fluid condition of the 

 greater portion of our globe. 



104. Barometrie Strain. 



The evidence which I presented in 1863 (Proc. Soc. Phil. Amer., ix, 

 283-8), of cyclical atmospheric strains resulting from the combined stresses 

 of pressure, inertia and elasticity, presents an interesting problem for 

 mathematical analysis. I confined myself to an investigation of mere 

 numerical results ; in generalizing and extending them, the following 

 FACTS seem most important : 



1. The atmospheric daily variation of solar or terrestrial centripetal in- 

 ertia is comparatively insignificant. 



3. The variation of tangential orbital motion, between noon and mid- 

 night, is about 3^2 of the mean motion ; the consequent variation in the 

 moment of inertia is about -^^ of the mean moment. 



3. The orbital moment of inertia is more than 4000 times as great as the 

 equatorial rotary moment. 



4. The combined influences of elasticity and orbital moment of inertia 

 tend to drive the atmospheric particles away from the Earth during the 

 first and third quarters of the day, and towards the Earth during the sec- 

 ond and fourth quarters. 



5. The sum of the instantaneously varying tendencies reaches a maxi- 

 mum in the middle of each quartei'. 



6. The ratio of the mean equatorial daily variation of the barometer 

 (above or below its mean altitude), to its mean altitude, corresponds very 

 closely to the ratio of equatorial daily rotation (34, 895 miles) to the sum of 

 Earth's synodic daily gravitating reactions against Sun's gravitating ac- 

 tion (864002 ^ 16.044 ^ 5380 = 23683300 miles). 



7. The time of maximum disturbance in each quarter of the day, is de- 

 layed about an hour after the middle of the quarter at tropical stations. 



8. The magnitude of the disturbances in the morning and afternoon is 

 increased by the atmospheric expansion which is due to solar heat. 



9. The magnitude of the disturbances during the night is diminished in 

 such proportion as to maintain the average quarter-daily change, which is 

 required by the actions and reactions of elasticity and inertia. 



10. The tendency to description of equal areas in equal times, leads ap- 

 proximately to the proportion, especially within the tropics, 



6^ : e^ : -.r : y-^. 

 In this proportion e represents the daily barometric range ; e^, the annual 



