ALTHOUGH far from perfect, it will be acknowledged that these tabular expressions are for the most part very good approximations, and that for practical purposes, the quantity of moisture present in the atmosphere may be deduced from the indications of the wet bulb Thermometer, by my formula with tolerable accu

racy.

THE monthly evaporation from a small surface, has been regularly noted since my observations commenced, but I have strived in vain to derive therefrom any correct Table of the rates of evaporation for different temperatures-the evaporometal was out of doors, so that the wind was always perplexing by its influence what might otherwise have been an uniform and calculable operation. By disposing the four years series of numbers, however, in a graphic form it may be shewn, that the rate of evaporation follows the compound rates of the temperature and the dryness—and in a very general manner for a small surface of 3 square inches, the depth evaporated during 24 hours, may be thus stated in inches :

My Tables will not allow me to extend this very rough estimate to other temperatures, and it must be remembered, that every increase of the surface, and more particularly of the depth of water, will diminish the evaporation. A surface of two square feet with one foot of depth, gave for 6 months not quite two-thirds of the evaporation noted in the register for the same period.

IN concluding my present remarks, I offer no apology for their length, since I hope that I have confined myself to subjects which it would have betrayed laziness and want of zeal on my part to have passed unnoticed. It would indeed have been as blameable, after collecting the facts and observations, to have omitted an attempt at their generalization, as it would have been to have cumbered the pages of a Scientific Journal, with the whole series of daily notices, instead of taking the trouble to abstract the monthly and annual means. The attention of Scientific men in India has lately been called by their brethren of the west, to Meteorological subjects, and in expressing my own readiness to promote the objects of their enquiries, I will venture to

hope that they have provided, or will provide us with standard instruments of comparison at some principal station on the Indian continent, for without these, most of our observations must continue to be susceptible of leading to inaccurate conclusions concerning the heat and other atmospheric phenomena of the globe.

traverses.

10,-4 from bottom-105+3+315—105×3=.315.

11,

25-traveress

16,-15 from bottom-digneous aqueous.

17,-The algebraic signs of multiplication in the formula should be all those of addition.

19,

4-resetting

resulting.

21, In the table-19h. 10m. 27s. 6-19h. 01m. 27s. 6. 22,-5 from bottom-tarbe -to be.

SCIENCE.

FROM THE PROCEEDINGS OF the Benares LITERARYSOCIETY.

ART. I.-Geological Section of a part of the City of Benares.

THE recent excavation of a Tunnel at Benares, for the purpose of draining the waters of the Mutsyoduree and Mundakinee tulaos into the Ganges, afforded an opportunity of examining the Geological strata of a portion of the bank upon which this ancient city stands. The site chosen for the undertaking, was a narrow neck of land which divides the Mutsyoduree tulao from the river. At this place, the smallest breadth is not more than 500 feet; however circumstances made it preferable to adopt an oblique direction so as to avoid the stone ghat of Trilochun, although the distance was thereby augmented to 600 feet.

THE excavation was commenced at the foot of the high bank of the river, by sinking a shaft to the requisite depth according to plans and levels previously taken. From this shaft, the perforation was conducted laterally through a stratum of firm clay, which did not require to be propped or supported while the masonry was in progress. By way, however, of laying a secure foundation for the stone work at the orifice, the shaft was carried deeper, until the firm clay was pierced, and the work was impeded by a moist sand underneath, which yielded a plentiful spring of water. It appears that the wells in the neighbourhood chiefly draw their supplies from this stratum.

It became necessary now to lay open a channel to the low water level of the Ganges, in order that the water of the quick sand might run off without incommoding the work.

THE section afforded by this new cut, shewed that the quick sand, (which however became hard and dry on exposure for a month or two), was nine feet in thickness, lying nearly horizontal; and that under it was a firm clay containing the calcareous concretions known by the name of kunkur. In this latter clay the foundations of the lower or subfluvial embouchure were constructed; it is therefore known to exceed 20 feet in depth.

B

To return to the Tunnel: the upper clay had a thickness of 30 feet, and throughout its mass were interspersed those small round nodules of kunkur which are distinguished by the name of bujree. These rendered the clay wholly inapplicable for the purpose of making bricks, which had at first been intended; some were indeed made by a mixture of the clay with river sand, but when the bricks were wetted, the slaking of the lime within them, burst them into small fragments fit only for soorkhee.

Ir is difficult to imagine what may have been the origin of these insulated concretions of calcareous matter. On examination of them in their recent state, they were frequently found soft, and with a thin white coat resembling a minute shell-the matter within had a dark brown colour, but nothing was sufficiently decisive to warrant an animal origin being ascribed to them. They differ, however, from the large kunkury masses in which shells are not apparent, and in the present instance at least the locality of the two evidently belongs to distinct strata of alluvial clay. I had before imagined that the bujree which collects in readiness, and is used for roads, &c. was nothing more than worn or broken fragments of common kunkur; but besides the well known hardness of kunkur which resists the action of water much more obstinately than even sand stone itself, (as observed by Captain FRANKLIN, at the Rewah Falls), the present evidence of their separate forma tion affords sufficient ground for suspending judgment until further investigation shall have been made.*

NOTHING Worthy of remark occurred in the first 150 feet of excavation, excepting an old well filled up with rubbish from which a piece of corroded iron was extracted. Upon sinking the first shaft of ventilation, however, at the depth of 15 feet below the surface of the bank, a number of half-quarried stones were found, of a large size; they were not united together in any way, but seemed to have been collected on what had been formerly the level of the ground for the purpose of some extensive building. Stones of the same nature are seen to protrude from the bank on the river side for a considerable distance; but no knowledge of their origin or even existence could be gathered from the present inhabitants of the spot.

BELOW these stones a sandy light soil extended fifteen or sixteen feet, under which the bildárs came upon the clay of the Tunnel.

As the Tunnel rose gradually upwards in its course, a seam of pure sand was met with, dipping at a considerable angle. In the

On the road to Juanpoor, a large barren plain may be seen, in which the whole soil seems to be impregnated with granular kunkur, without any mixture of the larger species.

Geological Section I have imagined this to be connected with the division of strata observed in the first shaft. This seam of river sand may be looked upon as the commencement of recent depositions. A bed of sandy earth, 15 feet thick rested upon it in which was found embedded a loose square brick of large dimensions, similar to those discovered in the foundations of the old fort, and consequently of great antiquity.

THIS stratum presented no difficulty to the miners, for although very soft and sectile it was consistent, and did not crack on exposure to the air, as was the case with the clayey strata.

ON passing the sandy earth, a formidable vein of pure sand again occurred, which threatened at first to arrest our farther progress. It fortunately however proved to bebut 2 or 3 feet in thickness, and necessitated only additional precautions in propping and vaulting.

It may be seen by the Section, that the foundations of the tunnel at the part just mentioned, were about 45 feet under ground, and that it had not yet reached the middle of its destined course. I was not therefore a little surprised to find that the whole superstratum henceforward consisted of "b,huräo" or artificial soil, containing broken bricks, tiles, and fragments of earthen utensils; it is principally with a view of recording so unexpected a circumstance that I have compiled the present brief notice, which may hereafter be rendered much more satisfactory when opportunities are added of examining the depth and extent of this artificial deposit-so strong an evidence of the antiquity of the town.

Two explanations may be offered of the manner in which so vast a quantity of recent earth has been accumulated. First, that the river itself formerly flowed in the direction of the several jheels which the Tunnel was designed to drain. Second, and this is the more plausible conjecture, that the low swampy ground was merely subject to yearly inundations, forming at such times a shallow arm of the river, such as is frequently seen in the Ganges. The main stream was probably then more to the South than at present, for it has evidently encroached upon its Northern bank. In these shallow channels, where the current is generally slackened, a deposit of sandy matter would occasionally subside such as that in which the large brick was discovered. Meantime the debris of huts and walls, earth removed from places where brick buildings were raised, rubbish and filth brought from all parts of a large town and emptied, as is the practise now a days, into the Gurha, gradually produced the accumulation, raised the level of the ground above the high water mark, and gained so much additional space for building. The streaks of sand which occur throughout the mass, perhaps indicate the accesses of intermediate inundations.