156 Aimospheric Origin of the Aurora, §c. 
dian, yet the author has not confounded them, but has shown 
that the former differ from the latter in the absence of the dip. 
- But the analogy is not restricted to position. . It was soon de- 
tected in the concomitant phenomena. I have shown, by tabular 
views, that the thermometer usually begins to fall, and the baro- 
meter to rise, ‘several days before each, and rain’ or snow to de- 
scend within one, two; or three days after them. In the cases 
subsequently presented, in which the number of hours between 
the aurora and storm has been carefully noted, I have usually 
found that the time has been about thirty six hours, and that 
there is a curious exception inthe case of two auroras on two or 
three consecutive nights, in which ease, the rain or snow is less 
likely to descend, or is deferred till nearly the usual time after 
the last. The same is true of the polarized. clouds, and of halos; 
in bothr of which, vapor, which had unquestionably been precipi- 
is redissolved, or otherwise disposed of, during the time 
and under the influence of the ci prepuriyor y to or at- 
tendant on the second exhibition. 
This interference of one aurora with the results af ¢ its mnie 
cessor, opens @ curious field of investigation, discloses a new anal- 
ogy between this and meteors of a confessedly aqueous origin, 
— refers to a general law the observed exceptions to the descent 
of precipitated vapor ° which so generally takes place after an au- 
rora. In almost every instance-in which this has been deferred, 
there have been traces of auroral action on the succeeding night, 
though sometimes masked by the moon. The following rule has 
had few exceptions, viz. If the evening of the day after an au- 
rora is totally clear, rio storm follows on the second day ; and 
conversely, if no storm is to follow, this evening is totally or 
nearly clear. This general clearness is itself one of the: ustial 
attendants of auroral action ; and I have for many years observed, 
that the morning following an aurora is, in this respect, remarka= 
ble; as compared. with other mornings. In this fact, and in the © 
unusual clearness of the night of the meteor—with the exception 
_ of some peculiar, transient clouds—we have proof of the: influ- 
; ence of an aurora, or the circumstances which precede and attend 
aS in eioeting the vesolntiont or ee of visible rages or 
is eni es us to explain or sininhiedint the fact of the non- 
‘ance of the storm, of which the first of two consecutive 
ey 
¥m 
