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India, it extends from the Phillippine Islands as far south as Java, and runs as far to the north as Barren Island, in the Bay of Bengal. In all of this tract there are ample evidences of the intimate relation of earthquakes and volcanoes. This relation and affinity being allowed, it only remains for me to make a few general remarks. From chemical researches, it is well known that various changes are going on in the surface of the earth, there being a constant state of waste and repair, chemical composition and decomposition, it cannot therefore be supposed that the interior of the globe is one inert and dormant mass. It is well known that at the periods preceding the eruption of volcanoes, earthquakes were frequent, and that various vapours, gases, and other substances, the result of chemical decomposition escaped suddenly at those periods, and must have been detained below, under a high state of compression, and that these eruptions were attended by a period of subsequent rest. May we not therefore reason justly from these visible effects that the same changes are going on at greater depths and in larger cavities in the interior of the earth by which explosive compounds, whether gaseous, or solid, may be produced, vapours condensed, and changes take place similar to those of volcanic action, although at so great a depth, as to be beyond the reach of observation, which however may be capable of exerting an excessive mechanical power, equal to that required to produce extensive earthquakes. There is a valuable remark in Ure's work, that primitive formations which are oxydized at the surface of the earth exist at a moderate depth devoid of oxygen in the state of simple combustibles, he states " that the crust of the earth consists mainly of six substances, Silica, Alumina, Iron, Lime, Magnesia, and Potash, which when reduced by the chemist to a state of simplicity, become the combustible elements Silicon, Aluminum, Calceum, Magnesium, Polassium, Iron, a mixture of which at common temperatures on coming into contact with water or moist air, would cause fire and explosion-and if the quantities were great, earthquakes and volcanic eruptions would ensue.”
Lyall, towards the conclusion of his first volume reasons “ that the renovating and destroying causes in the earth are constantly at work, the repair of land being as constant as its decay, the deepening of seas keeping pace with the formation of shoals-he says that if in the course of a century, the Ganges and other great rivers have carried down to the sea, a mass of matter equal to many lofty mountains, we also find that a District in Chili one hundred
miles in area, has been uplifted to the average height of a foot or more, and that the cubic contents of the mass that added in a few hours to the land may counterbalance the loss effected by the aqueous action of many rivers in a century." He seems to consider that the dimensions of the planet remain uniform; the internal accession from below by mineral springs and volcanic vents, being counteracted by actions of a different kind, the amount of subsidence and elevation being so proportioned that the distance of the surface from the centre remains unchanged. In his conclusive remarks regarding earthquakes " he says that the constant repair of dry land and the subserviency of our Planet to the support of the terrestrial as well as the aquatic species, are secured by the elevating and depressing power of earthquakes, this cause he says, so often the source death, and terror to the inhabitants of the globe, which visits in succession every zone, and fills the earth with monuments of ruin and disorder is nevertheless a conservative principle in the highest degree, and above all others essential to the stability of the system.” This reasoning of the learned geologist will certainly be more consolatory to the world at larye than to those persons whose household property has been disarranged by the late convulsions in Bengal. They doubtless will not be inclined to attribute a conservative agency to that earthquake in particular, they are however the only persons, who from local knowledge can be best capable of supporting an opinion as to the amount of subsidence or elevation whether or not any gaseous vapours escaped from the soil in this instance, and if there are any volcanic products in the districts in which the vibrations of the earthquake were felt. It seems to be generally supposed, that the continent of India is deficient in evidence of volcanic agency, which surely must be owing in some degree to the want of geologi. cal scrutiny ; the only work which I have casually had it in my power to peruse, is a survey of the Hyderabad country by Doctor Voysey, in which I observe ample proofs of volcanic agency, although the author does not seem to attribute these to the real cause; the nature of many volcanic substances not having been so well understood in the period at which he wrote, as it is now. tions that there are many hills in the neighbourhood of Hyderabad consisting of trap, which has an appearance of having been once in a fluid state and that many of the granetic hills are covered with this substance. In one particular instance, the hill of Koulas, there
was a trap vein which had the appearance of having been ejected from below in a fluid state. The elevated table land of Beder consisting of iron clay rests on a substratum of basaltic trap. In the bed of the Godavery there are two hot springs, rising up through beds of trap, one of which is surrounded with blocks of porous, black Limestone--now as to the origin of trap formations, Maccul. lock states their mineral composition in all fundamental points resembles that of trap formations ; during the period however in which he wrote, the dispute regarding the aqueous and volcanic origin of trap was carried on with great acrimony; on consulting therefore later authorities, it is said, that trap formations, like common volcanic products have a tendency to recur in the same spot, also that they contain cavities exactly similar to those observed in the scoriac of volcanoes. The identity of the chemical composition of Basalt and Lava is mentioned, the constant occurrence of trap rocks in volcanic districts ; that chalk under a bed of trap has been found converted into granular marble, there are other evidencies, but the above are sufficient to prove the intimate relation between trap formations and visible volcanic products.
V.--Hints for establishing a new system of supplying tanks with water, adapted particularly for the Carnatic, to enable the cultivation of rice and agriculture in general, to be carried to an indefini'e extent without being dependent on the fall of rain in any particular district for a supply of water.
By Lieutenant H. Harriott, 36th Regt. M. N. I. The subject of the following paper is one well calculated to excite a degree of interest in the public mind at any time, but is more particularly deserving of attention at the present period at the close of a season of almost unexampled scarcity and distress occasioned by the failure of the periodical rains.
Throughout the Carnatic there are large and rapid rivers which during some period of the year are filled from bank to bank, and during the remainder are mere beds of sand.
Hitherto the useless waters have pursued their rapid course to the ocean without benefiting the country through which they pass, except in some cases, where the even surface of the plain has been favourable to directing the stream into artificial channels and by that means irrigating a considerable portion of land, but this plan is naturally contracted in its operations and it depends on the ingenui. ty of man to retain those vast floods of water, which now flow by unused and unheeded. It is evident that Providence has ordained that these rivers should answer other purposes than merely being drainers of the land.
Every person travelling through this country must have observed large tracts of fertile and valuable soil yielding no returns but allowed to run waste. The question naturally occurs from whence does this arise, to which the answer invariably received' is, a want of water; and it in consequence, becomes an object of the first importance, alike to the government, and to the people, to ascertain by what means the requisite supply of this essential element can be oltained.
The following detail though in itself imperfect, may it is hoped, be the means of attracting attention to this interesting subject.
The few opportunities that have been afforded me of acquiring information on the subject, prevents me from placing the ideas that have suggested themselves to me in so advantageous a light as a more competent person would be capable of doing. I have generally observed that near most rivers and in many cases connected with them, are deep, and extensive ravines. It appears to me that at a small expense, small in comparison with the enormous lavished in keeping in repair the numerous tanks throughout the country, these ravines might be formed into basins, capable of containing an immense body of water, the said basins having a canal (the neck as it were attaching the head to the body,) between them and the river, with floodgates to be shut or opened at pleasure, should the nature of the ground be adapted for the purpose, and in most situations such will be found to be the case, the sides of the basin may be elevated considerably above the level of the river. To fill the basin, under such circumstances, a steam engine would be requisite for raising the water from the river and conducting it into its allotted channel. If a forcing pump can raise a volume of fluid to the height of 32 feet by mere manual labour, it will only require an engine of limited powers to throw up water to the extent of 20 feet, allowing 20 feet below the surface the full depth will give a fair average of the quantity required, of course the extent of ground to be brought into cultivation will depend on the supply of water that the reservoir is capable of containing, allowing for evaporation, the
number of cubic feet of water by actual measurement can be ascertained, and a proportionate quantity of ground planted or laid out with the certainty of realizing one or more crops which at present can never be the case whilst dependant on the precarious state of the weather. How often in this country, it may be asked, has the toil of the peasant and the seed been thrown away from the want of a small quantity of seasonable rain to bring the crop to maturity ; so partial indeed is the rain, that whilst one part of the country is comparatively deluged, another within so short a distance as 50 miles is almost dry. This is not the case however with regard to rivers, which flowing through a vast extent of country and in most cases feeling the influence of both monsoons, are certain at some period of the year of containing an abundant supply of water, and should apprehension prevail of a failure of that supply by the river going rapidly down, it will only be necessary to increase the power of the engine to derive additional advantage from it, while it lasts.
When the quantity of water in the reservoir which is above the level of the plain has been expended, the same engine may be employed in raising the remainder-a strict attention to the theory of hydraulics will greatly economise the power to be put in motion. Surely, if the enormous sums expended on tanks under the present system (such for instance as that of Carongooly) can repay with profit to the renter, and advantage to the government, their aggregate outlay, even when four or five successive seasons fail in production, and from what I have been able to ascertain, it appears that only in very favorable years the tank is completely filled, and the whole of the paddy land brought into cultivation, the new system will certainly produce an immense net revenue or interest on the outlay of capital after the payment of the labourer, and the contingent expenses of working the engine. At first from the novelty and difficulty of procuring Engineers the expense
of cultivation will be greater than when clever and scientifie natives are brought forward, and I am sure there are many to be found both capable and willing after a little instruction to superintend the management of the engines : in proof of this opinion I would adduce the instance of how closely all mechanical improvements from England are copied by the Indian artisan.
The floodgates of the reservoir might be constructed of iron, wrought in the works at Porto-Novo, and fuel for working the engines