Q. I noticed in your paper of December 8,1881, a method of fitting up a boiler with two ranges, so as to be heated from either or both at once, and herewith send you a drawing of another and better manner of doing the same, thereby securing a more perfect circulation, as I question if the water-backs would have a sufficient supply through the ordinary coupling when both ranges were in use at the same time. They would likely be unpleasant on account of noise, if not dangerous.

When only one range is used the cold-water pipe is brought into the water-back through the end nearest the boiler, and the hot-water pipe is carried out from the opposite end, and around behind the range between it and the brick-work, keeping at about the same level till near the boiler, where it rises and enters the side-connection.

A. The objection to this method is, as much water cannot be warmed by passing it first through one back and then through the other as would be the case if each back circulated separately to the boiler. This will be plain when we consider the water cannot take as much heat from the upper back as from the lower one, as the difference of temperature will be less between the water in the upper back and the fire than it. will be in the lower one.

Figure 102.