He later enclosed some fragments of whinstone in a black-lead crucible and subjected it to intense heat in the reverberating furnace of an iron foundry. (He was in consultation with Mr. Wedgwood on the scale of heat, and with Dr. Hope and Dr. Kennedy, chemists.) After boiling, and then cooling rapidly, the contents of the crucible proved a black glass. Hall repeated the experiment, and cooled more slowly. The result was an intermediate substance, neither glass nor whinstone—a sort of slag. Again he heated the crucible in the furnace, and removed quickly to an open fire, which was maintained some hours and then permitted to die out. The result in this case was a perfect whinstone. Similar results were obtained with regular basalts and different specimens of igneous rock.
Hall next experimented with lava from Vesuvius, Etna, Iceland, and elsewhere, and found that it behaved like whinstone. Dr. Kennedy by careful chemical analysis confirmed Hall's judgment of the similarity of these two igneous products.
Still later Hall introduced chalk and powdered limestone into porcelain tubes, gun barrels, and tubes bored in solid iron, which he sealed and brought to very high temperatures. He obtained, by fusion, a crystalline carbonate resembling marble. Under the high pressure in the tube the carbonic acid was retained. By these and other experiments this doubting disciple confirmed Hutton's theory, and became one of the great founders of experimental geology.
It remained for William Smith (1769-1839), surveyor and engineer, to develop that species of chronology that Hutton had ascribed to organic remains in the solid strata, to arrange these strata in the order of time, and thus to become the founder of historic geology. For this task his early education might at first glance seem inadequate. His only schooling was received in an elementary institution in Oxfordshire. He managed, however, to acquire some knowledge of geometry, and at eighteen entered, as assistant, a surveyor's office. He never attained any literary facility, and was always more successful in conveying his observations by maps, drawings, and conversation than by books.
However, he early began his collection of minerals and observed the relation of the soil and the vegetation to the underlying rocks. Engaged at the age of twenty-four in taking levelings for a canal, he noticed that the strata were not exactly horizontal, but dipped to the east "like slices of bread and butter," a phenomenon he considered of scientific significance. In connection with his calling he had an opportunity of traveling to the north of England and so extended the range of his observation, always exceptionally alert. For six years he was engaged, as engineer, in the construction of the Somerset Coal Canal, where he enlarged and turned to practical account his knowledge of strata.
Collectors of fossils (as Lamarck afterwards called organic remains) were surprised to find Smith able to tell in what formation their different specimens had been found, and still more when he enunciated the view that "whatever strata were to be found in any part of England the same remains would be found in it and no other." Moreover, the same order of superposition was constant among the strata, as Werner, of whom Smith knew nothing, had indeed taught. Smith was able to dictate a Tabular View of British Strata from coal to chalk with the characteristic fossils, establishing an order that was found to obtain on the Continent of Europe as well as in Britain.
He constructed geological maps of Somerset and fourteen other English counties, to which the attention of the Board of Agriculture was called. They showed the surface outcrops of strata, and were intended to be of assistance in mining, roadmaking, canal construction, draining, and water supply. It was at the time of William Smith's scientific discoveries that the public interest in canal transportation was at its height in England, and his study of the strata was a direct outcome of his professional activity. He called himself a mineral surveyor, and he traveled many thousand miles yearly in connection with his calling and his interest in the study of geology. In 1815 he completed an extensive geological map of England, on which all subsequent geological maps have been modeled. It took into account the collieries, mines, canals, marshes, fens, and the varieties of soil in relation to the substrata.
Later (1816-1819) Smith published four volumes, Strata Identified by Organized Fossils, which put on record some of his extensive observations. His mind was practical and little given to speculation. It does not lie in our province here to trace his influence on Cuvier and other scientists, but to add his name as a surveyor and engineer to the representatives of mineralogy, chemistry, physics, mathematics, philosophy, and various industries and vocations, which contributed to the early development of modern geology.
REFERENCES
Sir A. Geikie, Founders of Geology.