Chase.] 262 [September. 



3. The inverse relations of specific gravity and atmospheric dens- 

 ity to temperature, and the direct relation of density to pressure. 



4. The observed proportionality of the heat generated by collision, 

 to the square of the obstructed velocity, in falling bodies as well as 

 in projectiles. 



5. The relations which have been pointed out between magnetism 

 and heat, — between magnetism and the solar spots, — between the 

 sun-spots and gravity,* — and between magnetism and gravity. 



6. The general theoretical proportionality of radiative to absorp- 

 tive power, and the practical confirmation of theory by Tyndall's 

 recent experiments. 



7. The variation of heat, gravity, and other central forces, in the 

 inverse ratio of the square of the distance, and the reasonable pre- 

 sumption of an identity of mechanical laws from the identity of the 

 "lines of force" in centripetal and centrifugal radiation. 



The average daily extremes of temperature, from the absorption 

 of solar heat and the cooling by nocturnal radiation, occur at about 

 S*" A.M. and 2'' p.m. The atmospheric gravity, in consequence of 

 the combined attraction of the sun and earth, is greatest at midnight 

 and least at noon. The temperature- and weight-disturbances do 

 not, therefore, correspond in their daily march, but by averaging on 

 eaoh side of the turning-points (so as to eliminate, as far as practica- 

 ble, the overlying perturbations of the heat which is alternately 

 stored and restored), we may discover some indications of a constant 

 ratio between the radiating and attractive energies of the sun. If 

 such a ratio really exists, and yet cannot be exactly determined, the 

 nearest attainable approximation to its value will be an interesting, 

 and, perhaps, a useful addition to our knowledge of molecular 

 physics. 



The " interior work" or latent heat that balances the condensation 

 of gravity, is greatest at midnight, when the solar attraction is added 

 to the terrestrial, and least at noon, -when the weight of the air is 

 represented by the difference of the two attractions. It seems prob- 

 able, therefore, inasmuch as the gravitation of a particle towards the 

 sun is .00067 as great as that towards the earth's centre, and as a 

 variation of 180° F. in temperature is accompanied by a variation of 

 .367 in volume, that there' should be, from this cause alone, an in- 



* Wo]fF's sun-spot formula is based on the masses, distances, and annual mo- 

 tions of Jupiter, Saturn, the Earth, and Venus. 



