270 «© British Association for the Advancement of Science. 
by sweeping into broad water what may extend so far. Now the 
excess of silt, on the seven hundred and thirty refluxes of tide that 
occur in a year, amounts to thirty five millions eighty seven thousand 
four hundred and fifty cubic yards, capable of spreading a layer, if 
equally disseminated, of twenty one inches thick over the first tide 
area; one third however is disturbed, and carried over the second 
tide area; or there is an uniform increase of the banks, and decrease 
of water in the channels of the estuary of the Mersey, amounting to 
seven inches perannum. ‘This deposition of matter is however very 
unequal, some parts of the coast and of the banks receiving great ac- 
cumulation, while others are often taken away. At the quarantine 
ground, the bed of the river shoaled up twenty two feet in eight 
years, and then eleven feet in two years, over a space of half a mile 
long by one quarter of a mile wide, and yet this was swept away in 
eighteen months. Captain Denham had been examining the port 
of Liverpool for fourteen years, and he infers from his observations, 
that a time will arrive when no access to this port could exist, unless 
man set bounds by his ingenuity, to the operation of tidal action. 
He made a number of local observations, which showed the diligence 
he had exercised in both planning and executing whatever he con- 
eeived might benefit this most important port; and he finished by an 
explanation of his principle of a constant sea level, which he had 
ascertained to be at three hours before, or three hours after high 
water, and by exhibiting the instrument which he had employed in 
drawing up water from different depths. 
Fossil Plants.—The President called on the Rev. Mr. Yates, 
who exhibited to the section some interesting remains of fossil veg- 
etables found in the new red sandstone of Worcestershire. He men- 
tioned the discovery of similar remains in the same formation in 
other parts of England, as at Coventry, where trunks of trees, of a 
considerable size had been found; and stated that in the Royal In- 
stitution of Liverpool is preserved a fossil trunk found in excavating 
Prince’s Dock. ‘The specimens laid before the section were from 
two quarries between Worcester and Ludlow, one in the parish of 
Stanford, and the other in Ombersley ; the former being where the 
new red sandstone joins the Silurian rocks. In this quarry the stone 
is rather greenish, like coal sandstone, and not unlike the Keuper 
of the Germans; but it may be traced ina line about ten miles, into 
sandstone of the usual red color. In the second quarry branches of 
trees have been discovered, and trunks partly converted into coal: 
each trank seems imbedded ina cylindrical mass of ferruginous 
