THE

STEAM ENGINE.

3

THE STEAM ENGINE, A SUBJECT OF POPULAR INTEREST. -THE OBJECT
OF THIS WORK.-DISPUTES RESPECTING THE INVENTION. HERO.-DE
GARAY. DE CAUS.-BRANCA.-MARQUIS OF WORCESTER.- PHYSICAL
PRINCIPLES. -ELASTIC AND INELASTIC FLUIDS.THEIR PROPERTIES.
-APPLICATION OF THESE PRINCIPLES TO THE ENGINES OF HERO, DE
CAUS, AND LORD WORCESTER. SIR SAMUEL MORLAND. PAPIN.-
ATMOSPHERIC PRESSURE. THE WEIGHT OF AIR. -LESS AT GREATER
HEIGHTS. -BAROMETER. -PRESSURE OF AIR. ELASTIC FORCE OF
AIR AND GASES. -FORCE PRODUCED BY A VACUUM. COMMON PUMP.
- PAPIN'S METHODS OF PRODUCING
OF THE CONDENSATION

RAREFACTION BY ᎻᎬᎪᎢ .

VACUUM.

SAVERY.

HIS DISCOVERY

A

OF STEAM.

(1.) THAT the history of the invention of a piece of mechanism, and the description of its structure, operation, and

uses, should be capable of being rendered the subject matter of a volume, destined not alone for the instruction of engineers or machinists, but for the information and amusement of the public in general, is a statement which at no very remote period would have been deemed extravagant and incredible.

Advanced as we are in the art of rendering knowledge popular, and cultivated as the public taste is in the appreciation of the expedients by which science ministers to the uses of life, there is still perhaps but one machine of which such a proposition can be truly predicated: it is needless to say that that machine is the STEAM ENGINE. There are many circumstances attending this extraordinary piece of mechanism which impart to it an interest so universally felt. Whether we regard the details of its structure and operation, the physical principles which it calls into play, and the beautiful contrivances by which these physical principles are rendered available; or, passing over these means, we direct our attention to the ends which they attain, we are equally filled with astonishment and admiration. The history of the steam engine offers to our notice a series of contrivances which, for exquisite and refined ingenuity, stand without any parallel in the annals of mechanical science. These admirable inventions, unlike other results of scientific inquiry, have also this peculiarity, that, to understand their excellence and to perceive their beauty, no previous or subsidiary knowledge is necessary, save what may be imparted with facility and clearness in the progress of the explanation and development of the machine itself. A simple and clear exposition, divested of needless technicalities and aided by well-selected diagrams, is all that is necessary to render the construction and operation of the steam engine, in all its forms, intelligible to persons of plain understanding and moderate information.

But if the contrivances by which this vast power is brought to bear on the arts and manufactures, be rendered attractive by their great mechanical beauty, how much more imposing will the subject become when the effects which the steam engine has produced upon the well-being of the human race are considered. It has penetrated the crust of the earth, and drawn from beneath it boundless treasures