meter, bright on both sides, working by the action of warm water below and the cooling effect of the air above.

17. Radiometer.-A four-armed, metallic radiometer with deep cups, bright on both sides.

18. Radiometer.-A four-armed radiometer, the vanes consisting of mica cups, bright on both sides.

19. Radiometer.-A four-armed radiometer having clear mica vanes, the direction of motion being determined by the angle formed by the mica vanes with the inner surface of the glass bulb.

GEOLOGICAL SOCIETY.

[Continued from vol. iv. p. 312.]

November 21, 1877.-John Evans, Esq., F.R.S., D.C.L., VicePresident, in the Chair.

The following communications were read:

1. 66 On the Glacial deposits of West Cheshire, together with lists of the fauna found in the Drift of Cheshire and adjoining Counties." By W. Shone, Esq., F.G.S.

The conclusions arrived at by the author in this paper were as follows. Like Prof. Huil, he distinguished a triple division of the deposits under consideration. 1. The Lower Boulder-clay, or, as he preferred to call it, Lower Glacial Drift, resting immediately upon the eroded surface of the Keuper, consists for the most part of compact clay, containing numerous and large striated erratics, together with a fauna of Scandinavian type, the Gasteropoda being generally filled with fine silt containing Microzoa. The author believed that the shells found in this deposit were principally distributed by groundice, which took them up and floated them off the shore. 2. The Middle Sands and Gravels, or Interglacial Drift of the author, consist chiefly of sands and gravels containing few (if any) glaciated stones. The fauna of this division is Celtic, with a few Scandinavian species derived from the Lower Boulder-clay; the shells were distributed principally by currents; and the Gasteropoda were seldom, if ever, filled with sand containing Microzoa. 3. The Upper Boulderclay, or Upper Glacial Drift, is composed for the most part of clay not so compact as the Lower Boulder-clay, and containing fewer and smaller glaciated stones, which are more abundant near the base. The fauna is Scandinavian at the base of the beds. The shells were distributed principally by ground-ice, and those of southern type derived from the Middle Sands and Gravels. The Gasteropoda are chiefly filled with silt containing Microzoa. The paper was accompanied by lists and tables of fossils, a large collection of which was exhibited in illustration of the paper.

[The Chair was then taken by Warington Smyth, Esq., M.A., F.R.S., F.G.S.]

2. "The Moffat Series." By C. Lapworth, Esq., F.G.S.

The fossils found in the highly convoluted Lower Silurian rocks of the southern uplands of Scotland are usually restricted to certain

narrow bands of black carbonaceous and Graptolitic shales, which, from their especial abundance in the neighbourhood of the town of Moffat, Dumfriesshire, are known to geologists as the Moffat Shales or Moffat Series.

The most perfect section of the black shales visible within the Moffat area is exhibited in the cliffs of the gorge of Dobb's Linn, at the head of Moffatdale. It was shown by the author that they are here disposed in a broken and partially inverted anticlinal, which throws off on both sides the basal beds of the surrounding non-fossiliferous grey wackes. They are distinctly arranged in three successive groups or divisions. Each of these divisions is distinguished by special lithological characteristics, and possesses a distinct fauna. To the lower and middle divisions a few fossils are common; but between the middle and upper divisions the palæontological break is complete. These divisions, again, are naturally subdivided into several zones, each characterized by special species or groups of species.

A larger exposure of the same deposits occurs at Craigmichan, a few miles to the south-west, where the beds of the lower division are shown to a much greater depth than at Dobb's Linn. In these two localities the general succession of the Graptolitic shales is as follows:

:

With the aid afforded by these sections, the thorough investigation of the ten subparallel black shale-bands of the Moffat area is rendered a matter of ease and certainty. Of these, the four bands lying to the south-west of Saint Mary's Loch are the most continuous. They were described in detail by the author; and it was shown that in each the only strata apparent are indisputably those of the type sections of Dobb's Linn and Craigmichan, with which they agree zone for zone in sequence and in all their characters, mineralogical and zoological. Here, also, the beds are arranged in greatly elongated anticlinal forms, the axes of which are, as a rule, inverted. In any single transverse section, the succession of the beds on the opposite sides of the median line of the band is identical; and the highest zone of the black shales everywhere passes up conformably into the basal bed of the surrounding greywackes. The varying width of the band is dependent simply upon the varying elevation of the crown of the anticlinal. Where the band is of least diameter, only the highest beds of the Birkhill shales rise from below the grey wackes. As the band expands, the underlying zones

emerge one by one in its centre, till finally, in the widest exposures, we recognize the deepest strata of the Glenkiln shales.

It was shown, by plans, sections, and descriptions of every exposure of consequence within the Moffat district, that precisely similar results are arrived at with respect to the remaining black shalebands. To the south of Moffatdale, the Moffat beds agree essentially with those of Dobb's Linn; but to the north the whole formation diminishes in collective thickness, and the highest division gradually loses its fossiliferous black shales.

These facts place it beyond question that all the carbonaceous and Graptolitiferous shales of the Moffat area are portions of one and the same originally continuous deposit the Moffat Series, which is now the oldest visible rock-group in the district, being everywhere inferior to the prevailing greywackes, through which it invariably rises from below in greatly elongated anticlinal forms.

In the rigid restriction of distinct groups of fossils to a few feet of the succession, the rocks of the Moffat series resemble the thinbedded Silurians of Scandinavia and North-eastern America. From analogy it may be suspected that they similarly represent an enormous period of time. The correctness of this inference is demonstrated by the evidence afforded by the known geological range of their organic remains. The Graptolithina of the Lower or Glenkiln division are those of the highest Llandeilo Flags of Wales, the corresponding Middle Dicranograptus-schists of Sweden, and the Norman's-Kiln shales that underlie the Trenton (Bala) Limestone of New York. The Hartfell species occur in the Bala beds of Conway, &c., the bigher Dicranograptus-schists of Sweden, and the Utica and Lorraine shales that overlie the Trenton Limestone. Those of the Birkhill shales agree almost species for species with the fossils of the Coniston Mudstone of Cumberland, the Kiesel-Schiefer of Thuringia, and the Lobiferous beds of Sweden, which lie at the summit of the Lower Silurians of their respective countries. Hence it may be considered certain that the Glenkiln shales are of highest Llandeilo age, that the Hartfell shales stand in the place of the Bala or Caradoc of Siluria, and that the Birkhill shales correspond to the Lower Llandovery.

The insignificant thickness of these three formations in the Moffat district is in strict agreement with the well-known north-westerly attenuation of the Lower Silurian rocks in Wales, England, and in Western Europe generally.

It was pointed out that these results, when carried to their legitimate conclusion, harmonize all the apparently conflicting facts hitherto collected among the Lower Silurians of the south of Scotland. We have a complete explanation of such difficulties as the remarkable lithological uniformity of the predominating strata, the absence of associated igneous rocks, the peculiar localization of the fossils, their identity along certain lines, and their rapid and peculiar impoverishment along others. We reduce, at a single stroke, the apparently gigantic thickness of the South Scottish Silurians to reasonable limits, and at the same time bring them into perfect harmony with those of Western Europe and America.

[75]

ON THE COMPOSITION AND THE INDUSTRIAL USE OF THE GASES ISSUING FROM METALLURGIC HEARTHS. BY L. CAILLETET.

THE remarkable investigations of H. Sainte-Claire Deville on dissociation, in opening to science a new path of research, have likewise promised to interpret a great number of metallurgical phenomena which had till then remained unexplained.

By collecting the gases which circulate in the hottest part of the furnaces in which iron is worked, I have been able, by means of apparatus similar to M. Deville's, to prove that the composition of those gases, suddenly cooled, is totally different from the results given by the analyses of Ebelmen. That skilful metallurgist, unacquainted with the phenomena of dissociation, collected the gases by slowly aspirating them by means of a long tube-which necessarily brought about the combination of their dissociated elements.

In Ebelmen's analyses the reaction seems almost always complete, while the cooling undergone by the gases shows that smoke and carburetted gases can subsist in presence of oxygen at the temperature of welding iron.

The gases collected at the top of the grating of an annealing-oven, at a point where the temperature is such that the eye cannot support the brightness of the bricks raised to a most intense whiteness, contain::

Independently of the carbonic oxide, there is found in the oxidizing atmosphere of the oven a large excess of finely divided carbon, which deposits itself on the tube, hot and cold, which serves for the aspiration.

In metallurgic works the gases issuing from welding-fires are generally conducted beneath generators, which thus produce without expense the supply necessary for the working of engines. The gases, therefore, rapidly cool against the walls of the boiler; thus, after traversing a length of 15 metres, their temperature is below 500°. They are then formed of

It may be concluded from this analysis that the quantity of oxygen has diminished by nearly one half, in reacting, not upon the carbonic oxide, of which the proportion has changed but little, but upon the finely divided carbon, which exists in large quantity,

as I have shown, in the atmosphere of the hearth. The cooling and extinction of the gases stops all reaction; and when the latter are thrown off by the chimney they still contain, as we see, large quantities of combustible materials.

The investigations which I have made for the purpose of taking up a portion of these gases, left hitherto unused, have demonstrated that it is easy to rekindle them by passing them over a fire, at the same time retarding their motion. It was with this view that, in my forges at Saint-Marc (Côte d'Or), I had a furnace of large dimensions set up to receive the gases as they issued from the generator. On arriving in this furnace, the section of which is more than 3 square metres, the gases lose a large portion of their velocity, at the same time that they are kindled in passing over a small grating on which coal-cinders, or some combustible of small value, are burned.

The high temperature developed in these conditions is utilized in my works for the annealing of sheet-iron. It is, in fact, known that rolling renders the iron brittle, and that it becomes covered with adherent oxide in the annealing-ovens. By heating the sheets thus altered for twelve hours in cast-iron boxes well closed, arranged in the gas-oven just mentioned, the sheets are found, after complete cooling, to have become perfectly malleable; and the oxide has disappeared, leaving the surfaces clean and bright. This reduction is easily explained if we remember the beautiful researches of MM. H. Sainte-Claire Deville and Troost on the passage of hydrogen through red-hot metals. I have likewise had the honour to communicate to the Academy* various experiments which prove that, on plunging a flattened iron tube into a fire, hydrogen passes through its sides, and, accumulating within it, causes it to resume its original form. The gases which have penetrated into the cast-iron box under the influence of the red-hot sides are therefore essentially reducing, and produce in a very short time complete deoxidation of the metallic surfaces.

In brief, we may conclude from my experiments :

1. That the gases issuing from metallurgic fires still contain, even after passing under steam-generators, an important quantity of combustible principles, and that, with the aid of the processes above described, it is easy to kindle them afresh and burn them almost completely.

2. That the passage of reducing gases through the red-hot metallic walls is capable of receiving applications in metallurgy which doubtless will not be limited to the particular case of which I have given an account.-Comptes Rendus de l'Académie des Sciences, Nov. 19, 1877, tome lxxxv. pp. 955–957.

ON A PILE IN WHICH THE ATTACKABLE ELECTRODE IS OF COKE. BY P. JABLOCHKOFF.

The coke burned in steam-engines produces work which, trans* Comptes Rendus, t. lviii. pp. 327, 1057.