Publisher's Synopsis
From the Author's PREFACE.
Since the appearance of Culmann's work, which marked an epoch in the history of graphical statics, the graphical method has attained pretty general dissemination in engineering circles; its advantages over the analytical have been recognized more and more, and its further development kept constantly in view. It is universally applied in the designing of stationary structures, - such as bridges, - for determining the requirements of the individual parts. In machine design, also, the graphical method gives valuable aid in finding the moments to which the machine parts are subjected, and in determining dimensions. Accordingly courses in graphical statics have been introduced in all technical schools. The graphical method has also been adapted with advantage to certain departments of dynamics, as in Radinger's "Dampfmaschinen mit hoher Kolbengeschwindigkeit," and Proll's "Versucht einer graphischen Dynamik." *
Iii all these determinations, however, friction and the special hurtful resistances to motion have not been taken into account. Heretofore all attempts to ascertain these hurtful resistances in machines, and to determine the efficiency which is dependent upon them, and is of such great importance in practice, have been confined to the analytical method, which is often awkward and at times utterly inapplicable. No method is as yet known to me by which the Motional resistances and efficiency of any desired mechanism can be graphically determined. In my lectures on machinery in the polytechnic schools of this place I have endeavored to show the relations existing between the forces in mechanism in a simpler form than that offered by the analytical method. Out of that endeavor has grown the following treatise, which in reality amounts to nothing more than a wider application of the long known but little used angle of friction.
My object in the present treatise was' principally to facilitate study for the students of the technical schools, upon whose time and industry increasing demands are made from day to day; perhaps the work may also be of interest and value to those more advanced.
* Radinger's Steam-engines with High Piston Speed, and Proll's An Attempt at Graphical Dynamics.....
