Mr. Bevan on the Cohesion of Cements. 53 



day, that it appeared there by a circuitous channel of informa- 

 tion, actually derived from Signor Nobili's communication to 

 himself. The first information I had of Nobili's method of 

 making the experiment, which was in its simplest form almost 

 the same with my own, and explained in terms nearly identical, 

 was not till the Annales de Chimie for December reached my 

 hands, which was on the 30th of April, when the foregoing 

 paper was in the press. 



Finally, as far as is yet known, no one except Signori No- 

 bili and Antinori and myself have yet obtained the spark from 

 the natural or permanent magnet. 



Greenhill, Edinburgh, May 7th, 1832. 



XIII. Remarks on Mr. White's Experiments on the Cohesion 

 of Cements; 'with a tabular Fieiso of their Results, reduced to 

 a common Scale. By B. Bevan, Esq. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



''■"'HE papers on Cements, communicated by Mr. White, and 

 ■*■ published in the Phil. Mag. and Annals, N, S., vol. xi. 

 pp. 264 and 333, are of considerable importance, on account of 

 the numerous facts they contain. They enable the architect 

 and builder to know where, and in what manner to apply the 

 different kinds of cement, and the degree of stress which may 

 be safely laid upon them. 



A careful perusal of the numerous results will point out 

 several common errors, in respect to the cohesive properties of 

 Roman cement and pozzolano, under different modifications, 

 and under various degrees of exposure to moisture. 



And as you probably may be of opinion that an abstract 

 of the results given in these papers, reduced to one common 

 scale in a tabular form, may be acceptable to some of your 

 readers, and save much time to individuals, I take the liberty 

 of sending one. 



Cohesive 

 Strength per 

 ^ square Inch.^ 

 lbs. mean. 

 Cement in bars, age 6 days, 1 dry 4'74'"J 



2 variable 360 V 356 



3 wet 234.) 



age 47 days, 1 dry 516"^ 



2 var 564 V450 



3 wet 27oJ 



