on the Priticiplc ofCementitiom Archiiccture. 189 



Much consideration has been bestowed upon the shape of 

 arches and arch-slones ; but if the observations be correct, at- 

 tention has been directed too largely to what is called the 

 equipoUence of arches, and too little to the intersection and 

 perfect union of the materials themselves. Were the whole 

 structure of a bridge completely united in its parts and any 

 adequate foundation obtained, it would hardly be possible that 

 it should fail even in the degree which Westminster or Black- 

 friars Bridges already have done. In Westminster Bridge the 

 arch-stones are larger and less numerous than the filling in 

 of the spandrels, though both are radiated. In Blackfriars 

 only the arch-stones are radiated, the filling in is in nearly 

 horizontal courses, and consequently not bonded with the 

 arch-stones. 



It may seem very difficult where labour is so dear as it is 

 in England, to work stones with the fair faces suggested ; but 

 there can be no doubt that this may be easily accomplished 

 by the employment of a steam-engine for the purpose of 

 tooling. 



Having made these observations on the cementitious and 

 bonded designs, a brief explanation may be necessary of the 

 situation of the bridge. This is perhaps sufficiently shown by 

 the plan, which represents a nearly square space on the Lon- 

 don side, and a lengthened parallelogram on the Southwark; 

 the houses to be removed being shown by a fainter shade of 

 ink than the old buildings, which are not interfered with, a 

 full detail of the buildings to be removed being a distinct mat- 

 ter from the construction of the bridge itself 



Proceeding to the aspect of the bridge *, the data given by 

 the Committee have limited in a certain degree the views of 

 the writer. As it is wished to make the expense of the structure 

 as small as may be consistent with the dignity of the work, 

 the balustrade so frequently employed in England is wholly 

 omitted. It is in fact no necessary part, and in itself an ob- 

 struction to the passenger ; yet as some decoration is desirable, 

 four metrae are introduced, one at each corner of the bridge, 

 on which may be inscribed the distances to various parts of 

 the kingdom as they respectively bear on each quarter ; and 



plugs and cramps, and dovetails and joggles cut in the stones themselves : 

 but all these apjjear inferior to a judicious interlacing of the materials 

 themselves. 



♦ The writer would not have chosen for this situation a bridge of five 

 arches, but preferred one of seven arches, which would have possessed 

 every advantage necessary as a water way, and be without the excessive 

 tpan of a fivc-arched bridge. 



an 



