of the Ganges; in the year 1846, its course in Persia, Turkey, and Arabia was most singular and capricious*, and in this country in 1849 its extension took place simultaneously from several centres and in various directions. It is next to be observed that the epidemic, though not compelled to move in any definite direction, has shown a decided tendency to follow certain tracks, or tracks having certain conditions, namely, the ramifying and tortuous lines of large rivers, and the low or flat districts in their neighbourhood, the lines of the sea-coast, and, less decidedly or less frequently, also, the great roads or lines of communication over land; while it has appeared to be arrested or checked in its course by mountains, and sometimes by seas, although at other times a sea or ocean has seemed to afford facilities for its extension. In its westward progress it spread in 1817 and 1818, especially along the valley of the Ganges†; and in 1821 and ... * It is described in the following words in the report of the Board of Health from dispatches received from foreign ministers and consuls :— "By the month of July it reached Teheran. ... From Teheran it proceeded by a north-west course to Tabreez. 1 From Tabreez it turned off in a south-east direction towards Ispahan, which it reached in September. . . . Then proceeding westward, it reached Bagdad at the latter end of the month. . . . From Bagdad, instead of pursuing its westward course, it again turned directly back in a south-east direction, taking the road through Cashan to Sheerez. . . . In October it entered Asiatic Turkey, breaking out at Mossul, and reaching as far westward as Diarbekr. At the same time penetrating into Syria, it spread to Damascus, in a few days reached Aleppo, and in the following month (December) it extended its ravages over the whole of the Upper Tigris, and the Lower Euphrates; thence advancing into Arabia, it reached Mecca early in January, 1847.” A similar account, but with some slight differences in the dates, is given by M. Verollot, physician to the French Embassy at the Sublime Porte, in the Echo de l'Orient, and is quoted by Dr. Dickson, in the New York Journal of Medicine, January, 1849. + Its progress is thus described by Mr. Jameson:-" From the rise of the disorder on the banks of the Ganges and Burrumpocter to its arrival at the mouths of the Nerbudda and Taptee, it" (the marked disposition of the disease to follow the course of rivers) "excited the surprise of the medical 1922, along the shores of the Persian Gulf and the rivers Tigris and Euphrates. The intervention of the sea had apparently delayed the progress of the epidemic from India to Arabia, and Persia; and now the mountainous regions of Circassia and Georgia, and of Asia Minor, seemed to retard its transmission to Europe. Having found its way, however, to the shores of the Caspian Sea, it soon extended to the European port Astracan at its northern extremity. In its subsequent march through Europe, it spread chiefly along the tracks of the Volga*, the Don, the Dneiper, and the observer. Thus, from Sonergong, in the Dacca district, where the epidemic broke out in July, 1817, it crept along the banks of the Megna to Naraingunj and Dacca, attaching itself chiefly to the ferries and marketplaces in its vicinity. In like manner it afterwards step by step advanced up the Burrumpooter, affecting during its transit the villages situated on both its margins. From the mouth of the Hooghly to its termination in the Ganges, near Moorshedabad, the same peculiarity was observable. The shipping at the new anchorage, at Diamond Harbour, and along the whole channel as high as Hooghly, was particularly affected, and almost every village adjacent to its banks buried many of its inhabitants. In the Bhaugulpore district the propensity was so strong, that the virus scarcely ever spread into the interior, whilst it almost depopulated the low lands near the Ganges. Again, in the autumn of 1817, Moozufferpore, and the villages along the Gunduk River, in Tirhoot, and the station of Chupra, on a branch of the Ganges in Sarun, were alone visited; while at a subsequent period the disease was thence communicated along the Gogra to numerous cities in the northeast quarter of our territories. From Allahabad upwards, along the channel of the twin branches there forming a junction, until the virus was lost under the hills. it wavered so little from the line of those rivers, that hardly a town or village lying remote from their course was brought within its influence. Without going further over our old ground, let us briefly state that the same rule held yet more unexceptiouably in Rajpootana, through the province of Bundlekund, and all along the Nerbudda to the numerous branches of the Chumbul."-Report on the Epidemic Cholera Morbus, &c., by James Jameson, Assistant Surgeon, &c. Calcutta, 1820, pp. 102, et seq. Thus, on the Volga it appeared at Astracan, on the 20th of July, 1830. lower Danube, advancing gradually from the towns at or near their mouths to those at higher points in their course, or on their tributaries; and in the north of Europe it followed the lines of the Vistula*, Oder, and Elbe, from towns on the higher parts of those rivers to the ports at their mouths, thus reaching the northern shore of the European continent. In Europe the influence of mountains in checking the progress of the epidemic was again manifested in the escape of the south western part of Germany, Switzerland, Italy, and Spain, for a long period after the parts of the continent traversed by the rivers above-named, as well as France and England, had suffered severely. And on the continent of America the preference of the epidemic for the course of large rivers was exemplified in the ravages committed by it along the river St. Lawrence, and the lakes beyond it, in the years 1832 and 1834, and along the Mississippi and its tributaries in the year 1840 †. Kostroma, on the 3rd of September, 1830. See Dr. Hawkins's History of Epidemic Cholera, p. 187; Moreau de Jonnès Rapport sur le Cholera Morbus, p. 290; Dr. Christie's Treatise on the Epidemic Cholera, p. 23; and the maps in those works. * On the Vistula it attacked Lublin, at the end of March. Warsaw, on the 10th of April. Dantzic, on the 29th of May. The epidemic of 1832 and that of 1834, alike ascended progressively the St. Lawrence River, and the lakes beyond, from Quebec. Of the asserted march of Cholera along great roads or lines of communication overland, there is much difficulty in citing satisfactory instances. There are, in fact, no clearlyestablished cases of the disease affecting many places successively along a single line of road of great extent, without appearing in other places on either side; while, from the way in which roads communicate one with another in most countries, it must, except under special circumstances, be most difficult to indicate the particular roads which the disease had followed. Moreover, in the cases where there has been the nearest approach to a succession of outbreaks along a line of road, the track of the epidemic has generally coincided likewise, either with the course of a river, or with a line of sea-coast. It is certain, however, that the disease can cross a large extent of country where there are no great rivers. Thus, in the spring of 1831, it crossed Arabia from Muscat to Mecca; and in India it seems to have made its way from the banks of the Ganges to Bombay independently of the course of the rivers, attacking large places in the interior of the (See Col. Tulloch's Report on the Sickness among Troops in British America, p. 32.) In the United States of America, the epidemic of 1849 advanced from New Orleans to the different towns situated on the Mississippi, and its tributaries, successively, as far as Chicago, on the Michigan Lake. Thus it appeared first at (See Dr. Wynne's Report to the General Board of Health, and Dr. Evans, on the Spread of Cholera, Chicago, 1849.) country between the two points named, such as Nagpoor and Jalnah, earlier than it appeared at the mouths of the only rivers by which it could have ascended to these places. from the east coast of the peninsula. The next point to be noticed in the general history of Cholera is, that in invading a new continent or new island, it almost invariably makes its appearance first in sea-ports, and not indifferently in any town on the coast, but usually at ports having considerable maritime traffic. Thus, in its course from India in the north-western direction, the following ports were the places in the respective countries at which it first appeared-Muscat, in Arabia; Bassora, in Turkey ; Astracan, in Europe; Leith, Sunderland, Hull, and London, in England; Dublin and Belfast, in Ireland; Quebec, New York, and New Orleans, in America. A further fact of importance is, the varying rate of its progress in different situations and at different times. The influence of mountains in arresting the course of the epidemic, and of flat districts, and the course of rivers, in favouring its extension, has already been mentioned. It remains to be noticed, that in different countries not presenting so great a difference in the character of the surface, the rate of extension has been very different. When first extending its ravages through India, its progress was comparatively slow: thus it occupied more than nine months (from March to the end of December) in passing from Ganjam, on the east coast of India, to Pallamcotta near Cape Comorin, a distance in a straight line of about 875 miles, travelling, therefore, at an average rate of about 21 miles a week; whereas, in Europe, in the year 1847, it advanced from Astracan to Moscow, a distance of about 700 miles, in less than two months, consequently at the rate of 87 or 88 miles in a week. In crossing the ocean, again, its rate of travelling has, in several instances, been very rapid. From Ceylon, which it reached in January, 1849, it passed to the Mauritius in November of the same year, traversing a distance of 2500 miles in ten months, the rate of transit, allowing the longest period, being 62 miles in a week. And in ten weeks after it had |