157 



LECTURE XIV. 



ON ARCHITECTURE AND CARPENTRY. 



X HE subjects, which we have lately examined, are to be considered as pre- 

 liminary to the particular departments of practical mechanics. The first di- 

 vision of these is to consist of such as are employed in resisting forces of various 

 kinds, but they may almost all be referred, without inconvenience, to the ge- 

 neral heads of architecture and carpentry, of which the principal business is, to 

 resist the force of gravitation. Architecture, in its most extensive sense, mav 

 be understood as comprehending carpentry, but the term is more usually ap- 

 plied to the employment of those materials, which are only required to resist 

 the effects of a force tending principally to produce compression, while the 

 materials used by carpenters are frequently subjected to the operation of a 

 force which tends to extend or to bend them: the works of architects beins 

 commonly executed in stone or brick, and those of carpenters in wood, besides 

 the occasional use of iron and other metals,- in both cases. 



The simplest problem in mechanical architecture appears to be, to deter- 

 mine the most eligible form for a column. The length and weight being sup- 

 posed to be given, it is of importance to investigate the form which affords 

 the greatest possible strength ; but it is somewhat difficult tQ^. ascertain the 

 precise nature and direction of all the forces which are to be resisted. If we 

 considered the column as a beam fixed in the ground, and impelled by a 

 transverse force, it ought to be much tapered, and reduced almost to a point 

 at its extremity; but it is seldom that any force of this kind can be power- 

 ful enough to do more than overcome tlie weight alone of the column, 

 and it is only necessary to regard the load which presses vertically on it; 

 and whether we consider the force as tending to bend or to crush it, the 

 forms commonly employed will appeat to be sufficiently eligible. ]\Ir. La- 



