He pursued his observations with unabated ardour, and in the two next years,
with his friend Mr Clerk, made several excursions into Galloway, the island of
Arran, and the neighbourhood of Jedburgh. In all of these he discovered
the same conjunction, though not in so complete a manner, as among the Grampians. In 1788, he made some other valuable observations of the same kind.
The ridge of the Lammermoor hills in the south of Scotland consists of the
Silurian or graywacke formation (then named primary by Hutton, but afterwards found to belong to the transition series), which extends from St Abb's-head
south-westward to PortpatrJck, and into the north of Ireland. The sea-coast at
Eyemouth and St Abb's-head exhibits striking sections of these rocks, which
there appear contorted and dislocated in a remarkable manner. The junction
of the graywacke with the secondary strata was an object of instructive interest
to Hutton. In the same year he accompanied the Duke of Athol to the Isle of
Man, with the view of making a survey of that island. He found the main body
of the island to consist of what he termed primitive schistus (graywacke), much
inclined, and more intersected with quartzose veins than the corresponding rocks
in the south and south-east of Scotland. The direction of these strata corresponded
with that of the graywacke rocks in Galloway, running nearly from east to west.
This is all the general information he obtained from that excursion. It was
reserved for later geological researches to determine the true nature and relations
of the Silurian or graywacke series, by means of the fossils which they have been
found to contain. It was not till after Button's day that geologists became palaeontological.
Notwithstanding his assiduous attention to geology, Dr Hutton found leisure to speculate on subjects of a different nature. A voluminous work from his pen made its appearance soon after the Physical Dissertations: "An Investigation of the Principles of Knowledge, and the Progress of Reason, from Sense to Science and Philosophy," in three volumes quarto. In this treatise he formed a general system of physics and metaphysics. His opinions on the former subjects were very singular. He deprives matter of those qualities which are usually deemed most essential, solidity, impenetrability, and the vis inertias. He conceived it to be merely an assemblage of powers acting variously upon each other, and that external things are no more like the perceptions they give, than wine is similar to intoxication, or opium to the delirium it produces. It would be vain in us to attempt to analyse this singular work, which cannot fail to recall to the mind the opinions of the ingenious Dr Berkeley ; the two systems agree in many material points, but differ essentially in others.
In deference to the opinions of so great a man as Dr Hutton, we shall inform our readers of the view taken of the moral tendency of his work by his friend professor Play fair, who no doubt scrutinized very deeply its metaphysical speculations, as he in part, if not altogether, became a convert of the Huttonian system. "Indeed," says he, " Mr Hutton has taken great pains to deduce from his system, in a singular manner, the leading doctrines of morality and natural religion, having dedicated the third volume of his book almost wholly to that object. It is worthy to remark, that while he is thus employed his style assumes a better tone, and a much greater degree of perspicuity than it usually possesses. Many instances might be pointed out, where the warmth of its benevolent and moral feelings, bursts through the clouds that so often veil from us the clearest ideas of his understanding. One, in particular, deserves notice, in which he treats of the importance of the female character to society in a state of high civilization. A felicity of expression, and a flow of natural eloquence, inspired by so interesting a subject, make us regret that his pen did not more frequently do justice to his thoughts." Dr Hutton was seized with a severe and dangerous
