dogs and equipage, until at length, after they had been several times upon the point of being swallowed up, the piece of ice was again united to the mass. There is a tradition among the Tchouktchis, that the strait which separates them from the opposite shore, towards the north, was not covered with ice, and that the inhabitants formerly traversed it in baydars, a sort of boat. They relate that a period, not very remote, (for all the inhabitants remember it still,) some Tchouktchis, to the number of seven or eight, accompanied with a woman, crossed the ice to go toward these mountains to fish for morses, and that a long time after, the woman returned to the country by the way of the Kurile Isles, and brought the news that her companions had been all massacred. This woman was sold into another part of the country, and after having passed from hand to hand, was carried to Prince of Wales's Land, from whence she found means of returning to her own country. From this account, it is to be supposed, that the country which Wrangel had in view to visit, is nothing else than an island. The people who inhabit the islands nearest Siberia, make use of reindeer, which renders it probable that they are only a colony of Tchouktchis, more especially as their languages are much allied. The Tchouktchis are in general large and well made; they have regular features, their nose is not flat, but their cheeks are very prominent. Our travellers also saw other islands which they named New Siberia. The route which they took to get to them may be seen upon the chart of the famous pedestrian traveller Cochrane, where it is traced with great fidelity. They made very extensive excursions in all directions, but saw no land. In their land-journeys they rode upon horses or reindeer, but they preferred the former. With regard to sledge-travelling with reindeer, it is very convenient upon ice. They made use of a sort of large sledge called narta, drawn by twelve or thirteen dogs; these animals were always of great use to them, in defending them from the white and black bears, and wolves, as well as by their astonishing sagacity. Their instinct always led them to find the best road, and when the travellers thought themselves strayed, the dogs brought them back to the way. The sagacity of these animals was such, that after having made a number of turns, they took the shortest way to return. The travellers passed several weeks upon the ice, sometimes upon enormous pieces covered with grey snow, sometimes upon thinner layers, which frequently separate from the mass, so as to be carried along by the current, and tossed about by the waves. In these critical moments, the dogs rendered them innumerable services; in the places where the ice was thick, they ran with rapidity upon the snow, barked, bit one another, and appeared intractable; but as soon as the route became dangerous, they became gentle, circumspect and docile; they often walked upon pieces of ice, which were not more than half an inch thick with the greatest precaution, and seemed to advance only according to the order of the person carried in the sledge. MM. Wran

gel and Matuchkin remained once for seventy days upon the ice, at a distance of several hundred versts from the shore. They were attended by several nartas laden with provisions; they buried these provisions under the snow and ice, and continued their journey, carrying with them what was absolutely necessary; and when their provisions were exhausted, they returned for what they had left. They did not fail to make astronomical observations whereever they could, but the fogs often prevented them. These fogs were so thick, that our travellers, drawn in their sledge, sometimes could not see the dogs which drew them. Frequently snowstorms overwhelmed the tents which served for their abode, and it was with much difficulty, when the storm abated, that they got themselves extricated. During the months of November, December, and January, when the intensity of the cold became insupportable, our travellers took refuge in felt cabins or tents, where the water froze upon the floor, and the ice rose to the height of upwards of two feet. A mass of ice, about five inches thick, served them for a window. In this icy region, the earth produced only heath and a sort of plant peculiar to the country; in summer, the sun did not leave the horizon for two months, and in winter, it did not appear for the same period of time. The maximum heat, in the middle of summer, is about fifteen degrees of Reaumur's thermometer; it freezes at night or when the sun is upon the decline. The dazzling whiteness of the snow produced diseases of the eyes; the natives wear a sort of mask formed of the bark of trees, in which very narrow slits are made for the eyes. The Russian officers wore a piece of crape folded four times; at the beginning they neglected to avail themselves of this contrivance, and were rendered nearly blind; they learned, however, to cure this malady, by introducing tobacco oil into the eyes, a remedy which, although effectual, has the disadvantage of exciting acute pain. Their ordinary food consisted of fish, and reindeer, and bear's flesh; this last had the property of strengthening them, but it also produced violent agitation in the blood, and prevented them from sleeping. The natives are poor, do not practise any trade, and have no other occupation than that of fishing and hunting; yet there are Russian merchants who go to these countries for trade.-Revue Encyc. Oct. 1824.

5.-Captain Lyon's Voyage.

Captain Lyon has been forced back to England by stress of weather, and the badness of his vessel. He found Sir Thomas Roe's Welcome much narrower than laid down in the charts, and full of shoals, but saw no ice in it. Southampton Island is broader than it was thought to be, or perhaps consists of several islands. Corrections have been made in the positions of some of the capes in Hudson's Straits. Captain Lyon's Narrative, in small octavo, with plates, comes out shortly: it will, we doubt not, like his former work, prove interesting.-Edinb. Philos. Journ.

SELECTED FOR THE MUSEUM.

On the Illuminating Power of Coal-Gas. By ADAM ANDERSON, Esq. A. M. F.R.S. E. Rector of the Academy, Perth.

THERE is no subject, perhaps, capable of being investigated in a rigid and scientific manner, with respect to which there seems to be so great a diversity of opinion, as that relating to the comparative illuminating power of oil and coal-gas. Though the gaseous products concerning which we have so many discordant statements, are publicly and daily exhibited in almost every quarter of the empire, and though the properties of both have attracted from men of science more than a due share of attention, it is not a little singular, that, amidst the multiplicity of facts which have been laid before the public, none has yet been adduced of a nature sufficiently decisive to fix, beyond dispute, the relative values of the rival gases. In such circumstances, I cannot imagine that any thing which I may communicate on the subject will set the matter at rest; but as I have some practical knowledge, not only of the manipulations by which the gases are produced and purified, but also of their chemical constitution and mechanical properties, it would be an affectation of modesty were I not to claim some degree of authority for the facts which I am about to state.

The gas which was the subject of the experiments I have to describe, was manufactured, in the ordinary way, at the Perth CoalGas-Work,-an establishment that was planned and executed under my directions, and respecting which, it may be proper to mention, that the whole of the arrangements for the production of the gas, (the separation of the tar, and the other purifying processes,) are essentially different from those of any other gas-work in the kingdom. In this brief notice, it is not my design to enter upon details, but merely to request your permission to lay before the public, through the medium of the Edinburgh Philosophical Journal, a few general results that may contribute something, at least, to the stock of information which is already in their possession. For this purpose, it will be sufficient to state, that the whole number of retorts at present in constant operation at the Perth Gas-Work is only three; while the number of lamps of various kinds, to which these retorts are found to afford an abundant supply of gas, is 650, including, however, nearly 100 which are only lighted on Sundays in churches. The lamps are of the following descriptions:

1 Jet

52

From this statement it appears, that a single retort at the Perth Gas Manufactory, is capable of affording an ample supply of gas to about 200 lamps, the greater number of which are Argands, and many of them batwings, burning upwards of twelve hours daily. This result, so very different from the number of burners supplied by a single retort in other places,* I ascribe to two causes: In the first place, to a more thorough decomposition of the coal, arising from the peculiar manner in which the retorts are set; and, in the second place, to a more effectual separation of the tar and other noxious products than has hitherto been effected by the modes of purification usually employed.

With regard to the gas itself, I shall avail myself of your indulgence to give the result of a considerable number of experiments, which I performed with a great deal of care, in order to determine its illuminating power, in reference to that of a Kensington candle of the description termed "short sixes." The first column shows the kind of burner; the 2d the number of cubic inches of gas consumed per hour; the 3d the number of candles to which the light was equal, as determined by the method of shadows; and the 4th the number of inches per hour which corresponded to the light of one candle.

The mean of these results is, that 323 cubic inches of the Perth coal-gas afford a light equal to that of a candle for an hour. Now, according to Mr. Milne's inquiries at different oil-gas manufactories, taken in connexion with his own experiments, it appears, that a burner consuming 1 cubic foot of oil-gas per hour, yields a light equal to that of 8 candles; or, which is the saine thing, 216 cubic inches of oil-gas afford, during the same time, a light equal to one candle. From these data, it follows, that the volume of oil-gas, is to that of the Perth coal-gas, giving an equal degree of light, as 216 to 323, or in the ratio of 1 to 11.

This conclusion, though agreeing in substance with the results. obtained by Mr. Leslie and Dr. Fyfe, must not be extended, however, to every species of coal-gas; as it cannot be doubted that the quality of carburetted hydrogen, obtained from pit-coal, must be

One retort supplies gas to about 100 burners in Edinburgh; to 45 in London; to 31 in Berwick, &c.

VOL. VI. No. 33.-Museum.

2 N

ple contrivances, be made to impel it at ten or twelve miles an hour. If we apply to the body to be moved on a rail-way a force just equal to the resistance due to the friction, it will not move; it will be exactly in a state of equilibrium. But the smallest increase of force will put it in motion. If this small increase of force be a constantly acting force, like that due to steam, its motion will be continually accelerated, and would, ultimately, become greater than any assignable limit. Here we see the advantage of steam power; animal power could never be so applied as to produce this effect; because, as the velocity of the vehicle increases, the draught of animal power is diminished, becoming small indeed when it reaches. the velocity of ten or twelve miles an hour. When the vehicle has attained any proposed velocity, whether that velocity be generated in the first instance by the continued action of the impelling force, or by any other means, it is merely necessary, in order that it should retain that velocity, that there should be an impelling force just sufficient to overcome the friction and the resistance to the air. Hence, on a rail-way, the expenditure of force due to a velocity of ten or twelve miles an hour, is very little more than that due to a velocity of two miles an hour. This is the grand mechanical advantage which a rail-road possesses over a canal. But it is on the application of steam, and on a consequent capacity of maintaining a constant action, however great the velocity of the vehicle, that this advantage depends. Without steam a rail-way would be of no use; it would possess no superiority over a canal. Animal power could not have been applied with any advantageous effect, because its draught diminishes so rapidly with an increase of velocity.

Another point in which a rail-road is very superior to a canal consists in this-that being subject to none of the difficulties which occur in the construction of canals, it can always be made in a direct line, and will commonly be the shortest distance between two given stations. Between Liverpool and Manchester, for instance, the distance by the three lines of water conveyance is upwards of 50 miles; by a rail-road it will only be 33 miles: thus one-third of the entire distance is saved, a circumstance which will be found to be nearly true of all the principal lines of road and canal in the kingdom. The conveyance on canals too is frequently obstructed in summer from an imperfect supply of water, and in winter from being frozen up. Again, goods transported on a rail-way are free from all the risks and damages incident to water conveyance. This is no imaginary evil. On the canals between Liverpool and Manchester, goods are exposed to the most violent storms and adverse winds, during a passage of 18 miles in the tide-way of the Mersey. For days together, when the wind blows strong from the north and south, these vessels cannot move against it. Packages of goods intended for exportation are frequently very materially damaged, but they are polished up previous to shipment, and pass inspection. On being opened in a foreign market, the secret is discovered, and an