on the Pri7iciple qfCevientitious Architecture. 187 



costly materials, must be contrived with the greatest skill, and 

 must be executed with the utmost nicety ; yet such a bridge 

 will from its very nature be ill adapted for great adventitious 

 and unequal weights; and a design upon that principle has not 

 been pursued, but one on the cohesive chosen. 



If we reflect upon the durability of edifices, and judge from 

 the remains of former times, we shall perceive that cohesive 

 buildings ai'e of three distinct formations : 



The first denominated the " Cyclopian," and considered to 

 be the most ancient of Grecian erections, has the stone or 

 marble so exquisitely wrought where the joints are made, or 

 otherwise so fitted as to form an almost homogeneous sub- 

 stance*. 



The second, the " Cementitious" consists of small materials 

 of almost every form and quality, so well united as in fact to 

 approach to a perfectly solid congruent body. 



The third, the " Bonded," may be seen in many works, ap- 

 parently of more recent date, having squared stone and marble. 

 These sometimes remain well united, and at other times are 

 so separated and injured by the action of the atmosphere and 

 vegetation, that in fact they cease to be, if ever they actually 

 were, adhesive to each other. 



Of these three methods of building, the Cyclopian is now 

 hardly practicable, on account of the vast labour it would re- 

 quire. The writer does not attempt to recommend its adop- 

 tion, but alludes to it, because whoever contemplates the pe- 

 culiarity of this mode of structure may better understand his 

 ideas. He therefore proceeds to advert to the system of 

 uniting substances of various forms and of small dimensions 

 by the intervention and assistance of cement, which appears 

 to him particularly desirable not only on account of superior 

 durability, but also on account of greater ease and rapidity of 

 execution at a comparatively small expense. The question 

 is whether we possess a perfect uniting body. 



The ancient buildings in this country as well as in others, 

 sufliciently manifest the indurating nature of lime f. Modern 

 discoveries have introduced various preparations of it and 

 combinations with it, which lead us to conclude that we are 

 tolerably well acquainted with its judicious employment. The 

 Dutch I'erras is un(]uestionably durable and excellent. Par- 

 ker's and Mulgrave's cements:}: possess eminently the setting 



• It is denied [by some] that cement is at all used. 



t This may in some measure l)e doubted, if Waterloo Bridge is to serve 

 as an example ; for in it the cement or mortar is so ill con)|)ounded, as to 

 suHi-r the lime to escape through the arches, where it forms incrustations 

 on the outside of the alone. :|. C)r Atkinson's. 



2 B 2 power . 



