128 P. E. Chase on Terrestrial Magnetism, &c. 
nomena of terrestrial magnetism which cannot be explained, 
either by the instantaneously received and instantaneously trans — 
mitted impressions which are made directly ‘upon the ether b 
attraction, heat, or rotation,—by the more sluggish oscillations 
of the air, which originate from the same sources,—or by 
combination of the two. aad 
very particle is exposed to the influence of these several lt 
pressions, the tidal waves of the solid earth having 4 range, 
according to Prof. Thomson’s calculations (Phil. Zvans., dil, 
@ corollary, 
ry eae Elasticity 
pet = F | Density — 
ae be something more than accidental. : a 
f we assume the atmospheric density as our unit, Piel and 
represent the aerial and ethereal elasticities by E’, E", respec 
ively, the proportion BE 
4:192,000:: |& , [& 
gives an approximate value for the density of the kinetic sethet 
D” =-00000000000108 = The magnetic and barometric 
tuations may perhaps furnish the necessary data for determintt 
the unknown ratio me 
po = oo auroral displays in frosty air, are rhaps owing to analo z0 
