to carry fire from the bottom to the top, valiantly consuming themselves in the operation.  Furthermore, they are frequently charged with shavings and splinters of wood, which, becoming dry as tinder, will respond at once to a spark from a crack in the chimney, an overheated stove or furnace-pipe, or a match in the hands of an inquisitive mouse.  They are, likewise, so arranged that no water can be poured inside them till they fall apart and the house collapses, for they reach to the roof, whose sole duty is to keep out water, whether it comes from the clouds or from a hose-pipe, but which, for economical reasons, is made sufficiently open to allow the air to pass through it freely, thus insuring a good draught when the fire begins to burn.  To complete the system and prevent the possibility of finding where the fire began, the spaces between the joists of the upper floors communicate with the vertical flues, and these highways and byways for rats and mice, for fire and smoke, for odors from the kitchen, noises from the nursery and dust from the furnace and coal-bin, are also strewn with builders’ rubbish, which carries flame like stubble on a harvest-field.

[Illustration:  MINED AND COUNTERMINED.]

“Brick houses, as usually built, are not much better, but that is not the fault of the bricks—­they are tougher than good intentions; they have been burned once and fire agrees with them.  In fact, there is no building material so thoroughly reliable, through thick and thin, in prosperity and in adversity, as good, honest, well-burned bricks.  But the ordinary brick house is double—­a house within a house—­a wooden frame in a brick shell.  Like logs in a coal-pit, the inner house is well protected from outside attacks, but the flames, once kindled within, will run about as freely as in a wooden building, and laugh at cold water, which, however abundantly it is poured out, can never reach the heart of the fire till its destructive work is accomplished.  Thrown upon the outer walls, it runs down the bricks or clapboards; poured over the roof, it is carried promptly to the ground, as it ought to be; shot in through the windows, it runs down the plastering, washes off the paper, soaks the carpets, ruins the merchandise and spoils everything that water can spoil, while the fire itself roars behind the wainscot, climbs to the rafters and rages among the old papers, cobwebs and heirlooms in the attic till the roof falls in, the floors go down with a crash and an upward shower of sparks, and only the tottering walls, with their eyeless window sockets, or the ragged, blackened chimney’s, remain.”

“One road leads to fire and the other to combustion; that’s plain enough,” said Jack; “but where do the merits come in?  I thought we were to learn the relative merits of bricks and wood.”

“Wood has one conspicuous merit, a virtue that covers a multitude of sins—­it is cheap; but let me first arrange the fire-escapes.”