The hydrodynamic interpretation included in the present work has been added subsequently, and the latter portion of the original paper has been revised and rewritten on the more secure basis thus afforded.
Chapters V, and VI, constitute a resume of that which is known concerning the aeroplane treated both from a theoretical and experimental standpoint.
Chapters VII, and VIII, present, for the first time, a series of investigations made by the author (dating from 1894, 1898, and 1902, but not previously published) of the principles governing the economics of flight, and their application in the correct proportioning of the supporting member; these investigations are based on the peripteral theory of Chapter IV, aided by a hypothesis, being in the main an adaptation of Newtonian method.[1]
Chapter IX, includes, with a discussion on the elementary theory of propulsion, an original investigation on the theory of the screw propeller founded on the peripteral theory of Chapters IV.. VII., and VIII. This theory leads to results that are in remarkable accord with experience, and enables a useful series of rules to be laid down as a guide to design; applied to the marine propeller, the theory gives a form quite in harmony with modern practice. The chapter concludes with a dissertation on the subject of the expenditure of power in flight.
Chapter X., with which the present volume concludes, is of the character of an appendix, being an account of the more important of the experimental researches in aerodynamics published to date, and to which references have been made in the body of the work. This chapter also includes an account of some hitherto
- ↑ The essentially Newtonian character of all methods based on the principle of the direct communication of momentum, in hydrodynamics, is not so widely recognised as it ought to be. Thus the Rankine-Froude theory of propulsion is a simple and legitimate application of the Newtonian theory (see Chap. IX.). Newton was careful to specify the nature of the medium essential to the rigid application of his method (prop, xxxiv., Book II., Enunciation); subsequent writers have unfortunately not been so careful, and error has resulted.
