Mr. Bevan's Experiments, fyc. on the Strength of Timber. 343 



The mean difference of each catalogue from that of the 

 Astronomical Society is inserted at the bottom of the respec- 

 tive columns : and will be found as follows : 



Bessel, 1815 = - s -004' 



1825 = + -151 



Brinkley, 1824 = + -017 



Pond, " 1819 = + -023 



1825 = + -351 



Pond, 1818 = + 0"'64 



1825 = + 1 '64 



} 



Riffht Ascension. 



North Polar Distance. 



LII. Additional Experiments and Observations on the Strength 

 of Timber. By B. Bevan, Esq. 



To the Editor of the Philosophical Magazine and Journal. 



Sir, 

 HPO the Table published in your last Number, page 270, may 

 ■ be added the following, which have since been submitted 



lbs. 



Cohesion per square inch. 

 19-500 

 14-400 

 18-000 + 

 20-240 + 

 8-900 — 

 11-700- 



to experiment : 



Spec. Gr. 



Apple -71 



Elm -69 



Hazle '86 



Hornbeam . . . . . *82 



Larch *57 



Plane *64 



Nearly all the species of wood submitted to longitudinal 

 strain, for obtaining the force of cohesion per square inch, by 

 the direct process, were also subjected to transverse fracture, 

 by a load applied to the middle of a transverse bar when sup- 

 ported at each end. 



Let I = length ; b, breadth ; d, depth of the prism in inches ; 

 iv = the weight in pounds applied on the middle; 

 c = the cohesion per square inch in pounds. 

 If the resistance to compression were equal to that of ex- 

 tension 1- 5 lw _ 



bd* ~ ° 

 the mean result of my experiments give for dry and seasoned 

 wood 



2 lw 

 bcl* 





and when the wood is green, unseasoned, or wet, 



llw 



TdT~ ~ c 



These 



