for either of the Inst two, as they are well contrived to catch up the heat which is apt to accumulate at the eud of the saddle furnace, and thus ensure a quicker circulation and greater economy of fuel than other forms of the saddle.

The most powerful and hence best adapted for extensive ranges of houses are those known as Upright Tubular boilers. If, instead of an upright water jacket enclosing the fire, as in the

conical boiler, we provide a series of upright tubes, and allow the fire to play amongst and around them, the result will be a tremendous increase of power and a proportionate increase of the consumption of fuel. In great undertakings in the way