vi PREFACE BY TRANSLATOR INTO ENGLISH
ing his models in water and circulating colored kerosene oil through
them, the models being built with glass sides to permit observation.
A great many illustrations and drawings of furnaces, with
more or less detail, have been printed from time to time. Atten-
tion was occasionally called to certain differences, generally to an
increase in the size of certain parts above those of some well-known
furnace. The reasons for changes not being stated, it was possible
to make many inferences.
While the title of this work, "The Flow of Gases in Furnaces/7
explains its purpose, it is an abbreviation of the title of the
French edition, which may be rendered into English as "An
Essay upon a Theory concerning Hot Gases in Furnaces based
upon the Laws of Hydraulics/7 The work treats of the develop-
ment of the flow laws of heated gases and the application of those
laws to the rational design of furnaces. Primarily, a furnace,
considered as an elementary structure, is merely a hollow structure
of refractory material, within which heat may be released. A
great many furnaces show that their designers had very elementary
ideas concerning the application and utilization of heat. Damour
has given the following definition of industrial heating, which
sums up the question:
" Industrial heating has for its objective the realization of a
temperature more or less high, with economy, within an enclosure of
known dimensions, making use of a selected combustible (or form
of heat energy), for effecting a certain operation or chemical reaction.
"High temperature, economy, various combustibles, fixed
dimensions of the furnace or its heating chamber, a certain
industrial operation—such are the five variables of the problem.
Industrial heating operations present an infinite variety of results
to be accomplished. The engineer must be able to see all sides
of the problem; he must understand the various furnaces required,
their proper operation, the correction of their defects, and above
all the rational solution of each particular case. Each phase of
the question calls for many different forms of knowledge, with
each of which the engineer must be equally familiar; but it is
essential that he carefully distinguish between them, lest he
become confused or fall into those errors which frequently retard
the progress of the science of furnaces."
In a preceding paragraph Damour states: "All forms of energy
may be converted into heat, either directly by a single apparatus