GEOLOGICAL SECTION 17 
Tue GroLocy oF THE Forest or Dean, May 22nd, 1890. 
Mr. Wethered gave this lecture a few days before the Society’s 
visit to the district. ‘The name Dean implies a clearing or open 
space in a forest, and may be ascribed to the Saxon tongue. The 
formation at the base of the Malvern Hills consists of Laurentian 
Rocks, May Hill is Cambrian, but the Forest of Dean consists of 
Silurian Rocks discovered by Sir R. Murchison, and named after 
the Welsh tribe that inhabited the district. On the Herefordshire 
Beacon there is a Camp of Caractacus who so long defied the 
Roman power. In the Silurian Rocks we find a great quantity of 
Trilobites with their numerous eyes. 
At the time of the formation of the Old Red or Devonian 
Sandstone, the Forest of Dean was the estuary of a large river. 
Near Drybrook and Coleford, in the Forest, there are beds of Old 
Red Conglomerate. Above this there are many coloured beds of 
<and and shale. Limestone occurs in one part, in the shale of 
which the remains of dragon flies are found. The Lecturer then 
put forward his own idea of the formation of a Coal bed. The 
plants grew thickly together and one upon another. In this struggle 
for existence the weakest had to yield and their victorious neighbours 
spread over them, in their turn to succumb to others stronger than 
themselves. So they went on layer upon layer of vegetable matter 
«hich as the pressure increased became coal. 
VIsIr TO THE GAS WORKS. 
On May 27th Mr. Hichens gave a lecture on Coal Gas to the 
members who had been selected to visit the Gas Works the next 
day. The lecture was illustrated by a series of experiments and 
diagrams. 
When we arrived at the Gas Works the following afternoon 
we were received by the Manager, Mr. Coombes, who most kindly 
conducted us over the works and explained every detail. The 
Cheltenham Gas Works are often known as the “ Model Gas 
Works,” from the perfection with which the process is carried out. 
The first and perhaps the most interesting thing to be seen was 
the “ Drawing the Retorts ” z.e. the operation of taking out the coke 
and of putting fresh coal in. The Retorts are arched ovens from 
six to nine feet in length made of fire clay. The mouth of the 
Retort is opened, and the coke raked out. Then the fresh coal is 
rammed in, large quantities of gas escaping after each shovelful is 
