very red loose rock, showing
that it is not its geological position, but its _structure_, that
makes it a good durable stone.

It is a remarkable fact that most of the pebbles included in the red
rocks are quartzites, or indurated silicious sandstones; and, as
showing that their solidity and hardness are due only to a further
continuance of the deposit of silica in the interstices, it has been
proved that the purple quartzites are purple only by reason of the
original coloration of the grains which have been enclosed between the
original grains and the secondary silica. Yellow sandstone is colored
also by iron, and I have frequently seen the red sandstone shading of
to the yellow without any division whatever. The various shades and
tints of sandstone are necessarily due to the coloration of the
individual grains.

Most of you will, no doubt, have observed the sort of marbling or
grain upon the stone of our old buildings, such as the Town-Hall,
which I believe was obtained from quarries occupying the site of the
St. James's Cemetery. This is due to what is called current bedding;
that is to say, the grains have been arranged along oblique lines and
curves instead of in parallel laminae. This stone, which is
geologically equivalent to the Storeton Stone, and of the same nature,
has stood very well. Some of the Storeton Stone, if free from clay
galls, although very soft when quarried, becomes hardened by exposure,
and will stand the weather much better than a harder and more
pretentious material.

The stone of Compton House is in a very good condition, although the
mason told me such was the hurry in rebuilding that they could not
stop to select the stone, and also that it is placed in all sorts of
positions with respect to its quarry bed. Perhaps the circumstances
that the stone is not in parallel laminae may have something to do with
its durability, notwithstanding this latter fact.

It would take a long Paper, and several evenings, to exhaust the
subject even of our local stones. I may mention, however, that the
quarries of Grinshill, between Shrewsbury and Hawkstone, yield a
beautiful white sandstone, of a finer grain than Storeton, but of a
similar quality.

Most of the public buildings of Shrewsbury are built of it, and I am
informed that it was to some extent used in the Exchange buildings.
The rocky substratum of a district can be well seen in its ancient
buildings, for in old times carriage was so importan