404 A. Hali—Astronomical Proof of 
on the very Gulf shore, we find deposits of the Port Hudson 
age (180 feet at the Five Islands on Vermillion Bay) shows, 
nevertheless, that a wieipindous amount of erosion was accom- 
plished during the time that the Mississippi occupied in scoop- 
ing out its channel, to a depth which, even below the northern 
ond of Louisiana, cannot be estimated at less than 500 
fee 
‘ae regards the modern epoch, I will merely remark that, 
while in ale axis of the ancient embayment the Mississippi 
river, through the singular instrumentality of mudlumps up- 
eaval, is rapidly pushing out the land into the Gulf waters, 
the latter are nevertheless gaining ground on almost the eae 
coast of Mississippi and Alabama; and the same is true of a 
eet of Vermillion Bay. Yet on the whole, the scent of 
ouisiana, as well] as that of Texas and Florida, is more than 
holding its own; and the shallowness of the water, even where 
rareama: arn does take place, will necessarily restrict the latter 
within narrow limits hereafter. 
Art. L.—On the Astromonical Proof of a Resisting Medium m 
; by AsapH HALL. 
THE return of Encke’s Comet during the oy cai shin and 
its very favorable position for observation will att the 
pe ee of astronomers to this, one of the most reared 
bodies of our solar system. Besides the interest belonging to 
1786—1795 wea time= 12087112 days 
1795—1805 =—1207°879..“ 
1805—1819 a = =1207 454. * 
In order oo for this diminution Encke adapter - 
= a resisting medium in He appears to 
> been led to this hy, pothesis in the first place on account or its 
_ inherent probability, and in this view he was sustained by 
