on t?ie Principle of Cementitious Architecture. 337 



ceding pier ; it supported five hundred weight and a half, and 

 broke in two pieces. 



The ninth pier, built of rough lumps of pozzolano, in imita- 

 tion of Roman walling, nine parts pozzolano and one and a 

 half part stone-lime, was not sufficiently dry to be experi- 

 mented upon. 



Continuation of Experiment, No. II. Mai/ I2th. — Two 

 wrought iron wedges were driven with sledge hammers at 

 two points equidistant from the centre of a transverse line 

 bisecting one side of the pier, for the purpose of splitting this 



pier. It resisted very long ; and when separated, it was found 

 that many bricks had not taken the mortar. 



The mortar was not completely dry; it would require another 

 summer to give it all the toughness and tenacity it can acquire. 



The same wedges were afterwards driven with the same 

 hammers, and greater effort, longitudinally. It resisted and 

 repelled the wedge several times; but when separated, the 

 mortar and bricks appeared to have resisted alike. 



A third attempt was made by driving the wedges vertically ; 

 when a new separation took place, exhibiting the same ap- 

 pearance as in the first separation. 



This experiment was made in the presence of Lord South- 

 ampton, Mr. Brunei, Lieutenant-Gen. Sir Alexander Bryce, 

 and many others. 



Fourth Experiment, May 20, 1825. — The adhesion of the 

 materials being in some measure ascertained by the foregoing 

 experiments, it appeared desirable to learn how far the appli- 

 cation of weight vertically would affect them, when the fol- 

 lowing trials were made at Mr. Bramah's at Pimlico, by sub- 

 jecting portions of the first-mentioned piers to the hydrostatic 

 press. 



First trial, pier A. Roman cement. Section one hundred 

 and ninety-six inches superficial. Cracked with 48,960 lbs., 

 the compression being continued until it was entirely destroy- 

 ed with 92,1 GO lbs., or il tons 320 lbs. 



N. S. Vol. 11. No. G,5. Mai/ 1832. 2 X Second 



