jBRISTOL NATURALISTS' SOCIETY. 
EXCURSION MEETING. 
From the Bristol Daily Post of September ist^ 1865, 
Tbe second excursion of this Society for the present 
season took place on Tuesday last, 29th inst., the locality 
chosen being Cheddar. Aboutforty of the members and their 
friends availed themselves of the opportunity of visiting that 
delightful and interesting place. The party was conveyed 
in two large breaks, furnisned by Mr. Wakeham, of King's 
Square, and the manner in which his horses performed their 
work gave great satisfaction. The route taken was over the 
Suspension- bridge, through Bourton, Backwell and Brockley, 
to Cleeve, where a brief halt was made, and thence through 
1 Congresbury and Dolbury, As many of the party walked 
up Church* Hill, the President, Mr. W. Sanders, F.R.S., 
called their attention to tbe strata of limestone on the right 
hand side of tbe road, in which were imbedded a large num- 
ber of flints. He stated that the occurrence of flints in chalk 
was probably familiar to almost every one, as also the fact 
that those flints were originally sponges and other low forms 
! of animal life which had become silicified by withdrawing 
the silex from its solution in the water of the sea, at whose 
bottom the carbonate of lime was deposited. It was not, he 
said, so common to find flints, such as these, which were 
formed in precisely the same way as the chalk-flints in 
mountain limestone; there were, however, other instances 
on the South flank of the Mendips. Mr. Sanders also 
pointed out the well-defined stratification on the hill upon 
which Dolbury Camp is situated, and said that though up to 
this point the "dip" (or inclination downwards mto the 
earth) of the beds had been towards the North, it would 
henceforward be in the opposite direction, towards the 
South. On the road towards Shipham, a field was noticed 
with a large quantity of Colchicum-autumnale, or Meidow 
Saffron, and near here also the botanists of the party met 
with a few other somewhat uncommon plants. At the top of 
the hill, whence a very magnificent view of the Bridtol 
Channel and the surrounding country was obtained, it was 
noticed that the crest of the Mendips had been reached, 
Iwhere tbe lowest strata came " up to clay," and as an evi- 
dence that the top of the great anticlinal had been passed, 
some Old Red Sandstone with a Southerly dip was pointed 
out. The general formation of the surrounding hills was 
briefly touched upon, the deposition of the Carboniferous 
limestone on the outer surface of the hills, and Kew Red 
Sandstone in the valleys, being explained. 
After arriving at Cheddar, the mem*iers dispersed to enjoy 
the beautiful scenery, and to follow out their special pursuits, 
A large number remained with the president, who kindly 
explained in full, and practically illustrated, the method of 
mscertaining the altitudes of various stations above the sea, 
by means of the Mountain Barometer. The principle of the 
process consisted in estimating precisely the pressure of the 
air at each station, as indicated by the height of the mer-r 
curial column, and, as the pressure varied inversely as the 
height, being Jess at greater elevations, the desired in- 
formation could be deduced when this was known. 
Though thus simple in principle, a trustworthy result 
required the observance of a great number of minute pre- 
cautions, as well as a repetition of the observations. 
When the visible length of the mercury column had been 
obtained with the greatest accuracy, it was necessary 
