refiners, sugar-refiners, tar dealers and boilers, thatched houses in towns, and turpentine-makers. It is a notable fact that the city of London, which is perhaps the most densely inhabited spot the world has ever seen, has long been exempt from conflagrations involving a considerable number of houses. "The devouring element," it is true, has made many meals from time to time of huge warehouses and public buildings; but since the great fire of 1666 it has ceased to gorge upon whole quarters of the town. We have never had, since that memorable occasion, to record the destruction of a thousand houses at a time, a matter of frequent occurrence in the United States and Canada--indeed in all parts of Continental Europe. The fires which have proved fatal to large plots of buildings in the metropolis, have in every instance taken place without the sound of Bow bells. A comparison between the number of fires which occurred between the years 1838 and 1843, in 20,000 houses situated on either side of the Thames, shows at once the superior safety of its northern bank, the annual average of fires on the latter being only 20 against 36 on the southern side. For this exemption we have to thank the great disaster, if we might so term what has turned out a blessing. At one fell swoop it cleared the city, and swept away for ever the dangerous congregation of wooden buildings and narrow streets which were always affording material for the flame. The means to be adopted to prevent the flames spreading, resolve themselves into taking care not to open doors or windows, which create a draught. The same rule should be observed by those outside; no door or glass should be smashed in before the means are at hand to put out the fire. _Directions for aiding persons to escape from premises on fire._ 1. Be careful to acquaint yourself with the best means of exit from the house both at the top and bottom. 2. On the first alarm reflect before you act. If in bed at the time wrap yourself in a blanket, or bedside carpet; open no more doors or windows than are absolutely necessary, and shut every door after you. 3. There is always from eight to twelve inches of pure air close to the ground: if you can not therefore walk upright through the smoke, drop on your hands and knees, and thus progress. A wetted silk handkerchief, a piece of flannel, or a worsted stocking drawn over the face, permits breathing, and, to a great extent, excludes the smoke. 4. If you can neither make your way upwards nor downwards, get into a front room: if there is a family, see that they are all collected here, and keep the door closed as much as possible, for remember that smoke always follows a draught, and fire always rushes after smoke.