Although a real Londoner looks upon a dense December fog as a common occurrence, and lights up his premises with as little ceremony as he would do at the close of the day, yet, to one unused to such a scene, there is something startling in the appearance of a vast city wrapt in a kind of darkness which seems neither to belong to the day nor the night, at the mid-noon hour, while the gas is burning in the windows of long miles of streets. The greatest marvel, after all, is that so few accidents happen in this dim, unnatural light, in the midst of which business seems to go on as usual, and would do, we believe, were the whole of London buried in midnight darkness at noonday, which would only be looked upon as a further deepening of the overhanging gloom. The number of lighted torches which are carried and waved at the corners and crossings of the streets add greatly to the wild and picturesque effect of the scene, as they flash redly upon the countenances of the passengers, and, in the distance, have the effect of a city enveloped in a dense mass of smoke, through which the smouldering flames endeavour in vain to penetrate. During a heavy fog many accidents occur on the river, through barges running foul of each other, or vessels coming athwart the bridges; for there is no seeing the opening arch from the rock-like buttress, as the whole river looks like one huge bed of dense stagnant smoke, through which no human eye can penetrate. If you lean over the balustrades of the bridge, you cannot see the vessel which may at that moment be passing beneath, so heavy is the cloudy curtain which covers the water. At such times the steam-boats cease running, and rest quietly at their moorings, for the man at the wheel would be unable to see half the length of his vessel. Sometimes a steamer coming up the river takes a fancy to a shorter cut, by trying to clear Blackwall Reach, and come overland through the marshes below Greenwich, or by running her head into the Isle of Dogs, where she lies aground until the next tide. Many lives have been lost through foot-passengers mistaking the steps at the foot of some of the bridges for the opening of the bridge itself, and, ere they were aware of it, rolling head-foremost into the river. Strong iron-railings have been erected during the last few years, and have put an end to such dreadful accidents: at the foot of Blackfriars-bridge, many, we have heard, thus lost their lives. At this time the pavement is greasy, and, though you keep lifting up your legs, you are hardly positive whether or not you are making any progress. You seem to go as much backward as forward; and some old Cockneys do aver that the surest way of reaching Temple-bar from Charing-cross would be to start off with your face turned towards King Charles's statue, to walk away manfully without once turning your head, and that, by the end of three hours, you would be pretty sure of reaching the point aimed at, should you not be run over.