Heroes of science

by P. Martin Duncan

Edward Webb was, like his pupil, self-taught, and very slightly acquainted with languages and general literature, but possessed of great ingenuity and skill in mechanics, mensuration, logarithms, algebra and fluxions. His practice as a surveyor included many things now conceded to the engineer, such as the determination of the forces of water, and planning machinery. His instruments were commonly invented, often made and divided by himself; peculiar pentagraphs, theodolites, scales, and even compasses and field books, of new construction enriched the office at Stow, and stimulated the young men who were fortunate enough to be placed in it, to thought and exertion. “I admired,” says the subject of this memoir, “the talent of my master, his placid and ever unruffled temper, and his willingness to let me get on, for I required no teaching.”

Speedily entrusted with the management of all the ordinary business of a surveyor, Mr. Smith traversed, in continual activity, the oolitic lands of Oxfordshire and Gloucestershire, the lias clays and red marls of Warwickshire; visited (1788) the Salperton tunnel on the Thames and Severn Canal, and (1790) examined the soils and circumstances connected with a boring for coal in the New Forest, opposite the Shoe alehouse at Plaitford. All the varieties of soil, in so many surveys in different districts, were particularly noticed, and compared with the general aspect and character of the country, and the agricultural and commercial appropriations. The arrangement of the lias limestone beds in Warwickshire contrasted with the neighbouring red marls at Inkborough, the boring for coal in some dark lias clays on the road to Warwick, the absence of arenaceous beds from the limestones of Churchill—these were some of the points treasured in a mind capable of combining them at a future time.

In 1793 we find him engaged in executing surveys and complete systems of levelling, for the line of a proposed canal. In the course of the operations which he performed in the summer and autumn, a speculation which had come into his mind regarding a general law affecting the strata of the district, was submitted to proof and confirmed. He had supposed that the strata lying above the coal were not laid horizontally, but inclined; that they were all inclined in one direction, viz., the eastward, so as to successively terminate at the surface, and thus to “resemble, on a large scale, the ordinary appearance of superposed slices of bread and butter.” This supposition was now proved to be correct by the levelling processes executed in two parallel valleys, for in each of the levelled lines the strata of “red ground,” “lias,” and “freestone” (afterwards called “oolite”), came down in an eastern direction and sunk below the level, and yielded place to the next in succession.

But at the same time it was known to Mr. Smith that the position of the strata of coal in Somersetshire was not generally conformed to that of the “red earth” “lias,” and other beds above; the same thing was proved to him by an inspection of the colliery at Bucklechurch, in Gloucestershire; he knew besides that the great faults which divide all the coal strata underground, were in general found not to divide any of the superincumbent rocks which formed the surface.

Geologists who, at the present time, notwithstanding the devoted attention which has been paid to the phenomena of local displacement, find a difficulty in understanding the causes, may imagine the perplexity in the mind of a discoverer. Mr. Smith felt this perplexity severely, but not long. The Canal Bill, on which he was engaged, received the sanction of Parliament in 1794; and one of the first steps taken by the judicious committee of management was to depute two members of their body to accompany Mr. Smith, “their engineer,” on a tour of inquiry and observation regarding the construction, management, and trade of other navigations in England and Wales.

The tour extended altogether nine hundred miles, and occupied between one and two months; by one route the party reached Newcastle, and by another returned, through Shropshire and Wales to Bath. Mr. Palmer and Mr. Perkins were gentlemen well acquainted with coal-working, and they willingly stayed to inspect every new invention applied to canals and collieries; but Mr. Smith’s treasured object of consideration on the road, that which occupied all his thoughts in the intervals of professional inquiries, was the aspect and structure of the country passed through, in order to determine if his preconceived generalizations of a settled order of succession, continuity of range at the surface, and general declination eastward, were true on a large scale.

It is needless now to say that his general views were justified; he found the strata from the vicinity of Bath and Bristol prolonged into the north of England, in the same general order of succession with the general eastward dip. There is, however, one part of the conclusions adopted in this rapid survey from a postchaise, which merits particular attention. He passed through York on the high road to Newcastle, and saw at a distance of from five to fifteen miles to the east the hills of chalk and oolite. He was satisfied of their nature by their contours and relative position, and by their position on the surface in relation to the lias and “red ground” occasionally seen on the road. This is, in fact, the only authority he could rely upon for drawing, in 1800, the continuations of the chalk of Wiltshire, and the oolite of Somersetshire, through the eastern parts of Yorkshire, but he drew them with a considerable approximation to accuracy.

Engaged for six years in setting out and superintending the works on the Somersetshire Coal Canal, Mr. Smith found but few opportunities of making known to scientific persons, the peculiar generalizations which had taken possession of his mind. But in the execution of these works he was putting his thoughts into practice, informing the contractors what would be the nature of the ground to be cut through, what parts of the canal would require unusual care to be kept water-tight, what was the most advantageous system of work. Another singular advantage attended this engagement. The notions which up to this time he had obtained regarding the distribution of organic remains were comparatively vague. He found peculiar plants in the “clift” above the coal, particular shells in the lias and oolites, but none in the red ground, and he had combined these simple facts so far as to see that “each stratum had been successively the bed of the sea, and contained in it the mineralized monuments of the races of organic beings then in existence.” But it was the necessity of possessing an accurate knowledge of the different sorts of rock, sand, and clay, which were to be cut through on the line of the canal, which led him to examine minutely and scrupulously into the distribution of the “fossils” which he had been in the habit of collecting. The result was a proposition which he proved to be locally true, and of practical value, and which has now a world-wide application, “that each stratum contained organized fossils peculiar to itself, and might, in cases otherwise doubtful, be recognized and discriminated from others like it, but in a different part of the series, by examination of them.” In other words, he discovered that strata are to be recognized by their fossils. He now remarked also the contrast between the rounded state and mixed condition of the fossils which lay in gravel deposits and the sharply preserved specimens lying in natural associations in the strata, and thus acquired a notion of the distinction between what were afterwards named diluvial and stratified deposits.

The possessor of all these generalizations, now (1795) twenty-six years of age, was still shrouded in the obscure village of High Littleton, but in this year he removed to Bath, and took up his abode in the central house of a short range of buildings called the Cottage Crescent, which occupied a picturesque and elevated site south of that city. “From this point,” says he, “the eye roved anxiously over the interesting expanse which extended before me to the Sugar-loaf mountain in Monmouthshire, and embraced all in the vicinities of Bath and Bristol. Then did a thousand thoughts occur to me, respecting the geology of that and adjacent districts continually under my eye, which have never been reduced to writing.” He continued to direct all the operations on the Somerset Coal Canal, and very copious note-books attest the constancy and exactitude of his attention to that occupation. To this cause, indeed, may be ascribed the extreme rarity of any essays, or even memoranda, from which the progress of his geological studies can be gathered.

That in January, 1796, he had begun to commit his thoughts to paper, in a lucid arrangement for publication, the written proofs remain. In 1797 he drew a larger general plan for such a work; but not till 1799, after his engagement ceased with the Coal Canal Company, did he make public his intention to compose a general work on the stratification of Britain, or enter on the prosecution of an actual survey of the geological structure of the whole of England and Wales.