REPORT ON
the town of Victoria, which may be likened to the bottom of a crater with a lake, prevents the dissipation of this gas, while the geological
or marshy origin of fevers will not here hold, for that "the hills are here not more woody than in other healthy places; some, indeed, where the epidemic of 1808 and 1810, as well as the endemic, were most destructive, are quite naked of trees, as Diudigal, Madura, and the rocks west of Seringa patam."
"Now, if it should be found, that this fever exists constantly and invariably among certain description of hills, when others of a different composition are as constantly free from the same, would it not become reasonable to suppose that the nature or composition of the rock itself must furnish the cause of the calamity?
"The hills where it is found to prevail, appear, at first view, to be quite harmless, as they are granite, which is the most common rock-kind on this globe. They con- tain, however, besides quartz, felspar, and mica, a great proportion of ferruginous hornblende, which, by its disintegration or separation from the rock, becomes highly magnetic, and in which, I suppose, the cause resides which produces this fever, This iron hornblende occurs in such besides a great train of other disorders. quantity, that all rivulets, public roads, indeed, all hollows along these hills are filled with its sand; from which, also, all the iron in this part of the country is manu- factured. This granite is remarkable for its disintegration, as it not only separates during the hot season in large masses of many tons, but crumbles as easily into its composing particles, and is found as sand in great abundance, not only near every rock, but near every stone, from whence it is carried by the torrents during the rains to the lower parts of the country, and thus forms the particular mark by which these hills may be distinguished from all others. It is generally not attracted by the magnet when united to the mass, even when it occurs as in hornblende state, or greenstone, in the greatest abundance, but after it has been separated it is attracted as much as any iron filing. This may be owing to the incipient state of oxydation, or, more likely, to the development of magnetism by the high tem- perature to which it has been exposed in the hot season, which also may have weakened the cohesion of the rock, and caused its disintegration in the mass.
"Hills of this description form the principal ranges of the Ghauts, as far at least as the Godavery; they predominate also among the smaller, and in single hills and rocks in the low country, so that they might be taken at the exclusive rock form ation of this country. However, fortunately, this is not quite the case. They are easily recognised at a distance by their very rugged and abruptly pointed appearance, and the great steepness at their tops. The ranges of this formation are also very interrupted, and generally consist of rows of single hills, although to the southward, I have found them also connected at bases, and in triple and quadruple ranges.”
Dr. Heyne then gives an excellent topographic description of the hills "which have rendered themselves known to Europeans for the malignity of the fever," and after that of such as are as "constantly free of the hill fever." This is the right kind of topography, but for obvious reasons we cannot here enter into it. The bills where the fever is "totally unknown," Dr. Heyne describes as "primitive trap, He then adds, that the which consists of quartz, felspar, and real hornblende." epidemic fever of 1808 stopped short at a range of hills of this latter composition, in the Coimbatore district-a remarkable fact.
"These two ranges of trap proceed with very little or no admixture of iron stone through the whole Baramahal, from Namcul to Darampoory aud Vellore; the rocks are sometimes compact hornblende and greenstone, or basalt, all belong- ing to the same formation; but here and there hills appear among them of iron granite, which stand in connexion with other ranges of that description in that province, both east and west of that valley, which have the hill fever as virulent as in other parts of the country, where whole ranges of these hills occur.
"A most remarkable instance illustrative of the above facts, and of my deduc- tions from them, I found at Tripatoor, which lies in the above valley, close to a I asked there a respectable large table-land, the rock of which is sandstone. native whether any such disorders as fevers were frequent in the country, but received in answer, 'No, thank God, not within ten miles of this place; at Το Javadymalle, a hill fort, where no man can live two days without getting it."
HONG KONG,
formation favours the retention of a morbific poison on the surface, to be occasionally called into deadly activity. There is no extent of marsh on the island capable of generating miasm; but the heavy rains are annually washing large portions of the mountain through deep ravines into the bay, and thus continually exposing a fresh rotten surface to the sun's rays, and preserving a focus of disease which will finally become endemic.
Vast quantities of the silt from the hills are being deposited along the shores of the harbour. Owing to this circumstance, and to the rapid receding of the tides from this coast, the bay is becoming shoaler every day. The average depth is only four to five fathoms, except in the stream, where there is six to seven fathoms. In no great interval of time, the harbour of Hong Kong will be too shoal in many places for large vessels.
Climate. It is difficult to convey by thermometrical registers an accurate idea of the climate of any place. The range of the thermo- meter will not indicate the pressure of the atmosphere; the barometer, in or near the tropics, is of little utility as an index; the hygrometer imperfectly shows the quantity of rain which is in solution; while the
this place a peon was dispatched with the simple order of bringing two or three stones from the rock of the hill, and some sand as might be found on the road. The man returned, and brought pieces of a rock composed of red felspar, quartz, and plenty of ferruginous hornblende; and the sand of the road consisted entirely of magnetic sand and particles of felspar.
"I must name now the Pulicat hills, among which, as far as they extend to the southward (Chittoor), the hill fever is totally unknown; I was particular in my inquiries on this subject, in the beginning of this year, when among them. They consist entirely of flinty slate, and are bare in some places as they are woody in others, and as lofty and as low as the granite hills.
"I come now to a country and hills where I have lived myself for some years, the Cuddapah district. It is divided from Gurrumcondah on the south, and from iron granite and the hill fever, by a range of flinty slate, The same bends there to the northward, where the ranges thicken as they advance, and leave narrow valleys as far as Cummuur, and further up the river Kishna. The whole or most of these hills belong to the clay-slate formation, some are calcareous, all however are free of the hill fever. Other fevers may occasionally be seen, such as simple intermittents and bilious remittents, but they do not, like the hill fever, run into a typhus, and the cautious may easily guard against and get rid of them.
"This is the largest extent of inland country which I know to be free of the hill fever, viz., from Cuddapah to Kishna near Chintapilly, a place that has been at all times dreaded for its fevers. There, the iron granite hills prevail again. To the westward of Cuddapah, the healthiness of the country extends to the Ganjecot- tah hills, which belong to the flatz trap formation, consisting of sandstone, lime- stone, jasper and hornstone pebbles cemented together, and which are perfectly free of magnetic ironstone.
"Bababudden is another range of hills which is remarkably free of hill fevers, although it lies between places of notoriety for such, as Seringapatam to the S. W., and Chittledroog to the N. W., and Naggury to the W., an unwholesome country amongst the Ghauts. It belongs to the clay-slate formation, and active magnets are found in large depositions on them. It rains on them for six months in the year continually, when plauts keep fresh and alive in the open air for many days after they have been taken out of the ground, or broken off the stem. observation, viz., that the hill fever on this coast exists exclusively among the hills of the granite formation, or where iron-stone is found in large quantities, will be confirmed, the more it is brought to the test."
In fact, my
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