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change in our habits than causing us to light our lamps and candles, and to move and drive about with more than ordinary caution.

" And why should we fear a November fog? Is it so deadly and so dangerous as people suppose ? On the contrary, is it not notorious that the London hospitals are clearer during November than at any other time of the year ? And is it not quite a mistake to suppose that these dense fogs are peculiar to London ? Are they not common to all large cities, though perhaps less frequent than in our metropolis ? We read of one that visited Amsterdam of so dense a character that people ran against each other, even though they had torches in their hands ;-two hundred and thirty persons were drowned by falling into the canals ;-their cries were heard, but people were afraid to advance to their relief. We also read of a great fog which occurred at Paris, one 12th of November, in which the obscurity was such that persons lost their way in the streets, as if they had been blind;-it was necessary to be near a very brilliant light to perceive a faint trace of it. Fourcroy, the celebrated chemist, described this fog as displaying itself in spiral groups like corkscrews, and that it had a remarkable taste. This Parisian fog certainly out-horrors our choicest London peculiars; ' for we never have any corkscrews, and the taste is nothing very particular.

“ To enjoy a London fog to perfection you should ascend St. Paul's cathedral some day when the sun's place in the heavens is but just discernible. After climbing up about three hundred feet through the dense fog of the churchyard, you will perhaps be surprised on stepping out upon the balcony to find yourself in the bright sunshine, with a fog below your feet rolling and subsiding like a huge sea. You are surprised at its small elevation, it scarcely reaches halfway up the cathedral dome. But is it not a beautiful, a remarkable sight?--the bright sun lights it up fantastically, and adorns it with a few faint-coloured tints, making it not unlike the effect produced by the webs of the gossamer spider covering a sunny field in autumn. On examining the structure of this fog, it is found to be by no means uniform ; a long depressed line marks the course of the Thames, illustrating the fact that a clear water-surface supplies the vapour of the fog less perfectly than damp ground. Here and there, like huge hummocks, the fog stands out denser than the surrounding parts, marking the vicinity of some great brewery, or a more than usually dense population, where houses are thick together, and smoke issues from every chimney. Yonder, where the fog stands so high, the subsoil is of clay, from which the moisture escapes with difficulty; in other parts, where the fog is low, the ground is of sand or gravel, through which the wet filters easily. The neighbourhood of the parks and the wider streets, and larger houses, are also indicated by the thinner texture of this vaporous ocean.

" London fog differs essentially from clouds and mists and dew properly so called. Clouds are formed in the sky at some height in the air; but fog is an earth-cloud formed at the surface of the earth, and seldom ascending many feet above it. Clouds and mists and dew are all wet and damp and uncomfortable ; but London fog is perfectly dry, and enfolds the city as in a garment. Dew is formed by the cooling down of the earth's surface below the temperature of the air sufficient to condense the moisture of the air upon it in liquid drops; whereas a fog is formed by a cold upper stratum of air coming in contact with a lower and warmer stratum, and partially condensing the vapour wherewith it is charged.

“But London fog consists of something more than vapour of water partially condensed. Every house contributes a number of little fiery volcanoes, which are busy all day long supplying to the air vapour of water, sulphur, carbon, as well as sulphurous, nitrous, and pyroligneous acids, and some other matters, all of which become to a great extent mixed with the vapour of the air. It must further be noticed that the various constituent parts of the fog, being formed at the surface of the earth, are in the same electrical state as the earth itself, and hence (the air being a non-conductor) they repel each other, and are repelled by the earth, and thus remain suspended. This also furnishes the reason why the fog is dry, and does not adhere to any surface. A

very moderate wind is sufficient to disperse a fog; but an increase of moisture at the surface without rain, or an increase of temperature without wind, generally makes the

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fog more dense, because the heat increases the evaporation of the moistened surface. Thus it often happens that London is free from fog during the middle of the night and the early hours of the morning, but as soon as the fires are lighted the fog begins to appear. It sometimes clears away about noon, and becomes more dense towards evening, as the gas and other lamps are lighted, but the chief reason probably is, that after sunset the natural fall of the atmosphere presses the fog nearer to the earth's surface, and consequently makes it more dense. The same cause also sends the fog down the chimneys which have no fire, producing in the apartments a strong odour of soot, or a smell as of something burning. By night this has often caused anxiety.

“ The London fog has a peculiar tidal motion, tending, however, rather down than up the river, towards the marshes, where it performs a peculiar service to our markets in supplying them with much finer wild fowl than are produced in districts not visited by fogs. These birds feed only during twilight, and as the fog extends the twilight over nearly the whole day, they are constantly feeding. Thus when the birds are caught in clear weather after a fog they are found to be in very fine condition.

“The appearance of fogs in different cities is frequently simultaneous. At the time a great fog prevailed in London, Dublin was visited by one of equal density. Fogs have been known also to precede a strong westerly wind at Manchester, London, and Paris, and by nearly the same short interval of time at each station.

“ The poet Crabbe gives a very true description of a fog at the sea-coast.

“When all you see through densest Fog is seen,
When you can hear the fishers near at hand
Distinctly speak, yet see not where they stand;
Or sometimes them and not their boat discern,
Or half conceal'd some figure at the stern ;
Boys who, on shore, to sea the pebble cast,
Will hear it strike against the viewless mast;
While the stern boatman growls his fierce disdain,
At whom he knows not, whom he threats in vain.'

CHRONICLE OF THE SEASONS.

LEAFLESS TREES.

To the lover of nature, the trees in casting off their summer garments of rich leaves only reveal to him fresh objects of beauty and delightful study in the marvellous construction of their noble skeletons, in the exquisite tracery produced by the intermingling of myriad branches and

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delicate twigs, in the lavish variety of character stamped upon each separate species of tree, and upon each individual

of that species. "I do not propose,” says Ruskin in his “Modern Painters," “to examine

the characteristics of each tree; it will be enough to observe the laws common to all. First, then, neither the stem nor the boughs of an oak, elm, ash, hazel, willow, birch, beech, poplar, chesnut, pine, mulberry, olive, ilex, carob, or whatever the tree may be, taper, except where they fork. Wherever a stem sends off a branch, or a branch a lesser bough, or a lesser bough a bud, the stem or the branch is, on the instant, less in diameter by the exact quantity of the

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branch or the bough they have sent off

, and they remain of the same diameter, or if there be any change, rather increase than diminish, until they send off another branch or bough. This law is imperative, and without exception; no bough or stem, or twig, ever tapering or becoming narrower towards its extremity by a hair's breadth, save where it parts with some portion of its substance at a fork or bud, so that if all the twigs and sprays at the top and sides of the tree which are, and have been, could be united without loss of

space, they would form a round log of at least the diameter of the trunk from which they spring.

“But as the trunks of most trees send off twigs and sprays of light underfoliage, of which every individual fibre takes precisely its own thickness of wood from the parent stem, and as many of these drop off, leaving nothing but a small excrescence to record their existence, there is frequently a slight and delicate appearance of tapering caused in the trunk itself; while the same operation takes place much more extensively in the branches; it being natural to almost all trees to send out from their

young

limbs more wood than they can support; which, as the stem increases, gets contracted at the points of insertion, so as to check the flow of the sap, and then dies and drops off, leaving all along the bough, first on one side, then on another, a series of small excrescences sufficient to account for a degree of tapering, which is yet so very slight, that if we select a portion of a branch with no real fork, or living bough to divide it, or diminish it, the tapering is scarcely to be detected by the eye; and if we select a portion without such evidences of past ramification, there will be found none whatsoever.

“But nature takes great care and pains to conceal this uniformity in her boughs. They are perpetually parting with little sprays here and there, which steal away their substance cautiously, and where the eye does not perceive the theft until a little way above it feels the loss; and in the upper parts of the tree, the ramifications take place so constantly and delicately, that the effort upon the eye is precisely the same as if the boughs actually tapered, except here and there where some avaricious one, greedy of substance, runs on for two or three yards without parting with anything, and becomes ungraceful in so doing."

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