Report on the Progress and State of Applied Mechanics. 207 



April 7, 1858. — Me. Bexce, Vice-President, in the Chair. 



A Report was read from the Committee " On Applied Mechanics," 

 consisting of Mr. James Robert Napier, Mr. Walter Neilson, and 

 Professor W. J. Macquorn Rankine. 



Report on the Progress and State of Applied Mechanics. By James 

 Robert Napier, Iron Shipbuilder; Walter Neilso^st, Mechanical 

 Engineer; and W. J. Macqitorn Rankine, LL.D., Civil Engineer. 



1. The subject of Applied Mechanics, including, as it does, every 

 application of the laws of Ibrce and motion to works of human art, is so 

 extensive and multiform, that a mere enumeration of all its branches 

 and subdivisions, and of the various objects to which they relate, would, 

 if complete and fully detailed in every respect, occupy more time than 

 can be devoted to a Report like the present. All that your Reporters 

 can pretend to accomplish, is to give to the best of their ability a general 

 view of the recent progress and present state of this vast division of 

 human knowledge and practice, with such illustrations and examples as 

 their own experience and study may most readily suggest to their 

 minds. 



2. The objects to which Applied Mechanics relate may, in the first 

 place, be divided into two great classes: Structures and Machines; — 

 Structures, whose parts are intended to remain fixed relatively to each 

 other, and whose requisites are — Stability, which preserves the relative 

 positions of the parts of a structure, and Strength, which preserves their 

 figures, connection, and continuity; and Machines, whose parts are 

 intended to move, and to perform work, and whose requisites are, not 

 only strength in each separate moving piece, and stability in the frame 

 (which is itself a structure); but Efficiency, which consists in the 

 adaptation of the moving power to the work to be performed. 



3. Certain objects, such as carriages and ships, may be considered to 

 belong to both classes — being regarLled as structures with respect to the 

 connection of their parts, and as machines with respect to their means 

 of propulsion. 



4. Each separate part of a machine, being required to preserve its 

 figure and continuity under the forces to which it is exposed, is itself a 

 structure, and subject to the principles which regulate strength and 

 stability. 



.'5. Thus, Applied Mechanics, regarded as a science, may be divided 

 into Tectoitics and Enebqetics, corresponding respectively to the two 



