We have often told our readers, as a lesson learned from careful experiment, that wood will take flame: not only without actual contact with flame but also by the long continued accumulation of a comparatively low temperature. We have seen wood when connected with a flue, take fire fifty feet from a furnace, and we have known a wooden frame enclosing a hot air flue, in which the thermometer did not rise over 75° at the time of the enclosure, take fire three years afterwards, though perfectly safe at the time of the enclosure. Many years ago, by some accident the right man got into the right place as Fire Marshal of Philadelphia, Mr. Blackburn. He had keen powers of observation, and in one of his annual reports he clearly showed that a large number of fires in that city originated from the steady accumulation of heat at low temperatures, and often at long distances from the source of heat. We have recurred to this so often that few persons probably, who have read the Gardener's Monthly in the past, have been burnt down by " defective flues." However, it is well once in a while to renew these old topics, and it may be useful to note what the American Manufacturer says: "At the Crescent Steel Works in this city a steam pipe 2 1/2 inches in diameter, carrying from 90 to 100 pounds pressure, was laid under ground about three years ago, encased in common pine boards about one inch thick.

A few days since occasion was had to dig up the pipe, and the whole length of the wooden drain was found to be charred and apparently burnt about three fourths of the thickness of the wood, the other fourth being partially rotted. The whole inside of the drain was turned to charcoal, with here and there spots of white ashes, showing that ignition had actually taken place. It seems probable that if the casing had not been excluded from the air by the earth covering it, it would have blazed and been entirely consumed. It is generally believed that a steam pipe cannot set fire to wood, but this case seems to prove the contrary, and it may explain the origin of many mysterious fires".