On top of the night mountain
More than two thousand years ago Hero of Alexandria produced the first apparatus to which the name of steam-engine could rightly be given. Its principle was practically the same as that of the revolving jet used to sprinkle lawns during dry weather, steam being used in the place of water. From the top of a closed cauldron rose two vertical pipes, which at their upper ends had short, right-angle bends. Between them was hung a hollow globe, pivoted on two short tubes projecting from its sides into the upright tubes. Two little L-shaped pipes projected from opposite sides of the globe, at the ends of a diameter, in a plane perpendicular to the axis. On fire being applied to the cauldron, steam was generated.
In order to include steam, electricity, optics, hydraulics, thermics, light, and a variety of detached mechanisms which cannot be classified under any one of these heads, within the compass of about 450 pages, I have to be content with a comparatively brief treatment of each subject. This brevity has in turn compelled me to deal with principles rather than with detailed descriptions of individual devices—though in several cases recognized types are examined. The reader will look in vain for accounts of the Yerkes telescope, of the latest thing in motor cars, and of the largest locomotive. But he will be put in the way of understanding the essential nature of all telescopes, motors, and steam-engines so far as they are at present developed, which I think may be of greater ultimate profit to the uninitiated.
While careful to avoid puzzling the reader by the use of mysterious phraseology I consider that the parts of a machine should be given their technical names wherever possible. To prevent misconception, many of the diagrams accompanying the letterpress have words as well as letters written on them. This course also obviates the wearisome reference from text to diagram necessitated by the use of solitary letters or figures.
I may add, with regard to the diagrams of this book, that they are purposely somewhat unconventional, not being drawn to scale nor conforming to the canons of professional draughtsmanship. Where advisable, a part of a machine has been exaggerated to show its details. As a rule solid black has been preferred to fine shading in sectional drawings, and all unnecessary lines are omitted. I would here acknowledge my indebtedness to my draughtsman, Mr. Frank Hodgson, for his care and industry in preparing the two hundred or more diagrams for which he was responsible.
Excerpt from: How it Works by Archibald Williams