Page:Popular Science Monthly Volume 38.djvu/473

Rh in America was put in operation June 18, 1875, at Rising Fawn Furnace, in Dade County, Ga. The particular construction there used was that invented in England by Thomas Whitwell. Its general idea involved a cylindrical air-tight chamber of boiler iron lined with fire-brick; this chamber was traversed by a number of vertical parallel walls or diaphragms, also of fire-brick. The operation of this stove was as follows, viz.: The whole interior was heated to a very high temperature by means of the waste gas of the furnace which passed through the stove in the spaces between the fire-brick diaphragms. As soon as the stove was sufficiently heated the gas was turned off, and the blast was forced through the stove; and, as it traversed the spaces between the fire-brick walls on its way to the furnace, it absorbed heat from them and consequently reduced their temperature. This alternate heating and cooling of the stove, by the passage for a certain time, first of ignited gas, and then by the air to be heated, could be so regulated by suitable valves that a temperature of blast could be attained much higher than was possible in an iron-pipe stove. In order to insure regularity of working and uniformity of heat, it is usual to have at least three (some furnaces have four, and in Europe five have been used) such stoves to each furnace.

Besides the Whitwell stove, there are at present a number of others of the second type in use, whose details differ somewhat, but they all have an air-tight chamber lined with fire-brick, as a common constructive feature; this chamber is filled with partitions, blocks, tubes, and perforated or loose brick, in a great variety of ways, for each of which is claimed peculiar merit by its inventor; but it is quite evident that the design of some of these stoves was inspired by the desire to avoid the consequences of infringing existing patents on tweedle-dum by constructing tweedle-dee.

A good idea of the internal arrangement of a