Mr. Bevan on the Strength of Cohesion of Wood. 269 



to render them, in every instance, successful. But every ne- 

 cessary direction for the successful employment of the method 

 alluded to shall accompany the description of it when trans- 

 mitted to you ; which will be done as soon as I have sufficient 

 time to look over the notes and observations made while the 

 subject was the object of experimental inquiry. 



I am, sir, your obliged servant, 

 Hereford, Aug. 31, 1826. Thomas Howldy. 



XL. Experiments on the Strength of Cohesion of Wood. By 

 B. Bevan, Esq. 



To the Editor of the Philosophical Magazine and Journal. 

 Sir, 

 HPHE following table exhibits the results of some experi- 

 -*- ments I have made on the cohesive strength of various 

 species of wood. 



The specimens varied in length from 9 to 13 inches, and 

 were reduced in a lathe for a small part of the length, near 

 the middle, to near half an inch in diameter, leaving at each 

 end something more in general than four inches long and 

 about ll-10ths diameter, for the purpose of being fastened into 

 cast-iron boxes, made of sufficient strength to bear a strain of 

 several tons weight. The wood thus prepared was secured 

 at each end in one of these iron boxes, and suspended verti- 

 cally at the end of a lever of suitable strength to bear a force 

 of five or six thousand pounds ; the operating strain being pro- 

 duced by the gradual and slow motion of weights of 200 

 pounds each, resting occasionally at intervals, of 5, 10, 15, or 

 20 minutes, and sometimes for some hours. In the course of 

 my experiments I occasionally found part of the larger ends 

 drawn out in a cylindrical shape when the lateral adhesion 

 was less than the longitudinal cohesion : in these cases the 

 number of pounds expressive of the cohesion is short of 

 what is due to the specimen, and in the table these are distin- 

 guished by -f, on the other bearing. Sometimes the specimen 

 broke during the motion of the weight, and therefore wxmld 

 have separated under a less force, with more time : these are 

 marked — . 



Yours, &c. &c. 



B. Bevan. 



A Table 



