The Quarterly Journal of Science

vicinity of the city of Vienne, but also that the nearest indications of igneous action to be met with occur about Issoire, in the neighbouring department of the Puy-de-Dôme, a town situated in a straight line at a distance from Vienne of about eighty English miles, or else near Puy-en-Velay, which is not less than sixty from the same locality.

It has, however, since been suggested to me, that I had overlooked a little group of volcanos situated round about Montbrison, the capital of the department of the Loire, a town which lies considerably nearer to Vienne than either of the places to which my attention had been directed, being in fact not more in a straight line than about thirty-five miles distant from the city of Vienne, and that it was possible, therefore, that the convulsions of nature to which Sidonius and Alcimus refer might find their explanation in certain eruptions of which this neighbourhood had still retained the impress.

I was, therefore, glad to avail myself of the opportunity of visiting, in company with my friend, Mr. Corfield, a Fellow of Pembroke College, Oxford, the above locality on our way to Switzerland this autumn, and I am now prepared to say that, without pretending to have surveyed the entire district, I saw enough to convince me, that no volcanic disturbance which had occurred within this area at so late a period as that alluded to could have escaped our notice, and that every indication of igneous action which presents itself throughout the country bears marks of a much greater antiquity.

Thus much at least I can venture to affirm, namely, that neither craters, streams of lava, scoriæ, nor even cellular trap, are to be met with anywhere within the limits of this district. On the contrary, the only igneous rocks which came under our observation consisted of a compact basalt, containing nests of olivine, a material which could only have been elaborated by the aid of great pressure, and under a different configuration of the surface from that now existing.

To descend to particulars-the granitic formation, which occupies a large portion of central France, may be seen extending to the west of Montbrison, but the valley of the Loire, in which this town is itself situated, consists of tertiary fresh-water beds, covered over in many places by thick deposits of alluvial matter.

On the right bank of the Loire, however, the granite is again seen, and stretches as far as the Rhone valley, in which Lyons is situated.

Farther to the south, however, occurs the Coal formation of St. Etienne, which consequently intervenes between the valley of the Loire, in which Montbrison stands, and the city of Vienne, situated on the banks of the Rhone, which also is built upon a granitic rock.

Now both to the north and south of Montbrison, is descried, elevated above the general level of the granitic formation, a number of isolated knolls rising abruptly to a height of 500 feet or upwards, and in general capped by the ruins either of a church, a convent, or a castle, for which these summits would have been especially well adapted, both as being conspicuous objects from a distance, and also from their steepness being secure from assault.

We visited several of these little detached hills, as for instance, St. Romain-le-Puy to the south, and Marcilly-le-Pavé and Montverdun to the north of Montbrison, and found each of them composed up to its summit of basalt, which also extended nearly down to the level of the surrounding country.

At St. Romain-le-Puy, and Marcilly-le-Pavé, the trap rock rested upon granite, but that of Montverdun was incumbent directly upon the tertiary formation, which, as before stated, is superposed upon the granitic rocks on the lower levels.

Moreover, to the east of the road leading from Montverdun to Montbrison is a ridge, the longer axis of which lies nearly from north to south, wholly made up of the same material.

About half an English mile from Montbrison itself, at a place called "Le Roche," occurs the most instructive section which came under our notice; for here about halfway up the hill the basalt may be distinctly seen intruding itself into, and thrust through the midst of the granite, which is in consequence uplifted, and manifests itself both above and below the igneous rock, in the quarry, where the latter for road purposes is extensively worked.

Indeed the granite occupies a much more elevated position than this on the hills to the west of the spot where the basalt is seen, for the latter is found only at a certain elevation, being bounded both above and below by the granite of the country.

Judging from these facts, which are thoroughly borne out by the negative evidence, stated in the former part of this communication, I should conclude, that a vast antiquity must be assigned to the basalts which occur about Montbrison, for one can only account for the isolated position in which they are found on the detached knolls scattered over the district, by supposing that they constituted a part of one great continuous sheet of volcanic materials, which once overspread the surface, and of which the intervening portions have been since removed by denudation.

Of course such a supposition removes their origin to an immeasurable distance in point of time from any physical convulsions of recent or historical date, and indeed from the whole modern class of volcanos which has been described in my former memoirs on this country. They remind one of the basaltic eminences met with in Saxony, which Werner referred to his imaginary floetz-trap formation, with reference to which we are also compelled to assume

that the detached knolls of basalt scattered over the country, and resting upon the sandstone rocks which there predominate, are remnants of some great overflow of molten materials which covered the country, when the now elevated peaks constituted its lowest level, and when in all probability the entire district lay submerged under the ocean. We are therefore only obliged to transfer to Vulcan the task which the renowned geologist of Freyburg attributed to Neptune, and to conceive that a flood of melted matter discharged from his subterranean workshop overspread the district, instead of the deluge of water which, according to Werner, had risen to the summit of the highest hills, and which had left behind it on its retreat those fleetz-trap rocks which he insisted upon referring to an aqueous origin.

It would appear then, that the conclusion at which I arrived in my previous memoir is in no respect invalidated by anything observed at or about Montbrison, and that we are still at a loss for any facts tending to show, that the lively picture drawn by Sidonius "of the earthquakes which demolished the walls of Vienne, of the mountains opening and sending forth torrents of inflamed materials, and of the wild beasts' driven from the woods by terror and hunger, retreating into and making great ravages within the towns," is to be regarded in any other light than as the offspring of a lively imagination, dwelling upon reports which had reached the author with respect to some fearful earthquake which may have occurred in the neighbourhood of Vienne.

III. THE MEANS OF TRANSIT IN INDIA.

1. Steam Navigation in British India. By G. A. Prinsep, Esq., Calcutta, 1830.

2. First Report of the Public Works Commissioners, Madras,

1852.

3. Statement showing the Number of Miles of new Roads or Navigable Canals opened for Traffic in each several Presidency of India, since the year 1848. Printed Parliamentary Paper, No. 92 of 1859.

4. Reports to the Secretary of State for India in Council on Railways in India for the years 1859 to 1865-66, inclusive. By Juland Danvers, Esq.

5. Statement of the Moral and Material Progress of India, 1864–65. Printed Parliamentary Paper No. 374 of 1866.

WHEN India first came into the possession of the East India Company there was scarcely, throughout the whole empire, one complete