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season, unlike our Indian scorching hot winds, is cool and refreshing even in the hottest weather, and not being so highly charged with humidity as the northerly winds, the vapour it contains frequently passes over the mountain without becoming visible. Oftener, however, it is changed into a mist or cloud, which covers the top of the mountain, and is seen on the lee, or Cape Town side, rolling down in large fleecy volumes, till it reaches a wanner temperature, when it again becomes invisible. The elevation of this vaiiishing point varies with the hygrometric state of the atmosphere, and the line, thus formed, is so distinct that were degrees to be marked on the perpendicular cliffs which over-hang Cape Town, a gigantic, but correct hygrometer would be furnished. I may here express my regret, that I possess no notes of the hygrometric condition of the atmosphere of the Cape, sufficiently accurate to be recorded.

The different eddies and counter-currents of air produced by the influence of the mountain, and by the interruption it occasions to the general current of air, are also interesting phenomena. Among others, a remarkable one is often experienced by ships entering the Bay with a fair wind. On reaching a certain point they are frequently taken a-back, and find themselves in a strong breeze blowing right out of the Bay; and few who have lived at the Cape can have failed to observe occasionally, a northerly and a southerly wind blowing at the same moment in different parts of the Bay, a line of confused ripple clearly marking the limits to which the adverse winds, extend; and I may add another curious appearance I have repeatedly observed at Wynberg in winter, when northwesterly winds are bringing large clouds over the mountains; viz. a circular spot of blue sky in the direction of Constantia, about 10° to 15° in diameter, and about 20° from the zenith, on reaching which the clouds become invisible, but after passing it, they resume their former appearance. It may probably be accounted for by their meeting at that point a current of rarefied air, which having found its way through a neighbouring gap in the range of mountains, has not been cooled by passing over their summit. Those acquainted with these localities well understand that the gap alluded to, is that through which the road to Hout's Bay passes.

I may conclude these remarks, with a memorandum of the mean temperature of Cape Town, and three other localities in the interior,

extracted from a printed statement I fell in with at the Cape, but I can neither attest its accuracy, nor explain how the means, there given, have been obtained.

"The mean temperature of Cape Town, inferred from a Meteorological Journal kept there for several years, is 67|°—the mean temperature of the coldest month is perhaps 57°—hottest 79°—mean of three recent winters 58°—of three summer months 77°—least heat during summer 63°."

"The temperature of the district of Stellenbosch deduced from the observations of a single twelvemonth is 66j°—extremes 87° and 50°. The temperature of Zwartland appears to be 66£°—extremes 89° and 54°—the exposure of the thermometers is at neither place external; they are suspended in spacious well-aired halls."

"At Tulbagh, situated in a valley of the great chain of mountains which divides the western from the eastern provinces of the colony, the mean temperature of the year is 66f°—that of the coldest month 55^°—of the hottest S0\°—extremes 94° and 92°—mean of the three winter months 56|°, of three summer months 79"; least heat in summer 61°."

CAPE OBSERVATORY.

Mean of Observations made at 3° 15' P. M.

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217

Report upon the Manufacture of Steel in Southern India. By Captain Campbell, Assistant Surveyor General.

The mode of making the Indian Cast Steel, or Wootz, is up to the present time a paradox with the learned of Europe.

Dr. Buchanan in his " Tour in Mysore," published the first account of the process, which he describes as fusing two pieces of iron in a crucible, two pieces of wood, and two green leaves.

In the 26th No. of the Madras Journal of Science, is given a reprint of a paper by Mr. Heath, with reference to a letter addressed by the Royal Society to the Right Honorable the Governor of Madras, in which he repeats Buchanan's statement, and speculates upon the theoretical action of the gases evolved from these two green leaves; but that he was unacquainted with the true principle of the process is made evident by his notice of Dr. Pearson's and Mr. Stoddart's opinions, that the steel is a natural product.

As supported by the opinions of good authorities upon the subject, it does not appear that any one has been sufficiently presumptuous to think of doubting the fact. This I, however, have taken the liberty to do, in some remarks published in the 6th No. of Dr. McClelland's Calcutta Journal of Natural History.

As it appeared to me that the native process of smelting iron was very rude and imperfect, and admitted of considerable improvement, without making such alterations as would be impracticable for the familiar use of the natives of India, I have had furnaces constructed, exact models of those in general use, and have had their process repeated, so that I might have opportunities of minutely examining every step of the process.

A result of my investigations, is, that the iron sand of India has the property, by a peculiar modification of the blast, and proportion of the fuel, of affording a natural steel of good quality as an immediate product of the ore, or what is technically called, a "natural steel," and on examining the common iron made by the natives from this ore, I find that it always contains ^ of steel, and often one-half of its weight.

As the iron used at the localities mentioned by Buchanan is made, (to my knowledge,) from the iron sand, the above fact at once affords an explanation of the process so long paradoxical which is, that the

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