ADDEND.] 



THE LARCH, 



323 



Results of Experiments, on the transverse Strength of Timber, 

 made at Mr. Atkinson's, Grove End, St. Johris Wood, on 

 Thursday, March 12th, 1818. 



The pieces were each an inch square, except No. 3., which 

 was only 8-10ths of an inch in breadth. The numbers in the 

 Table show the weights it would have borne if it had been an 

 inch square ; the pieces were supported at each end, and 

 were loaded by putting 5 lbs. at a time into a scale suspended 

 from the middle; — the distance between the supports 30 inches, 



Description of 

 Timber. 



No. 1. 



Memel 

 Timber. 



No. 2. 



Red 

 Larch. 



No. 3. 



Red 

 Larch, old 

 and very 



dry. 



No. 4. 



English 

 Oak. 



No. 5. 



En«itsh 

 Oak. 



No. G. 



Ri.ua 



Timber. 



Compar. stiffness — ~\ 

 or the weight that / 

 bent each piece f 

 half an inch J 



145 lbs. 



80 lbs. 



93 lbs. 



60 lbs. 



65 lbs. 



125 lbs. 



Compar. strength — } 

 or the weight that C 

 broke each piece ) 



212 lbs. 



253 lbs. 



295 lbs. 



222 lbs. 



231 lbs. 



212 lbs. 



Compar. extensibi-") 

 lity — or the space | 

 through which the S- 

 middle had bent at [ 

 the time of fracture J 



2'25inch. 



3 inches. 



2 '75 inch. 



2 *5 inches 



1 # 4 inch. 



1-3 inch. 



Weight of a cubic"] 

 foot of each kind J 

 of timber in the } 

 nearestwhole num- J 

 ber J 



34 lbs. 



40 lbs. 



31 lbs. 



41 lbs. 



46 lbs. 



90 lbs. 



Remarks. 



Broke 

 short. 



Splin- 

 tered. 



Broke 

 short. 



Broke 

 short. 



Splin- 

 tcre (1 



Braft* 



short. 



As the strength of small pieces depends much on the position 

 of the annual rings, the pieces were placed as nearly alike in this 

 respect as possible. When the pieces were in the position in 

 which they were broke, the dark lines or portions of the annual, 

 rings that appear in the section of a piece were vertical. — From 

 the results exhibited in the preceding Table, it appears jrerj 

 clearly, that Larch is best adapted to resist the force of a body in 

 motion;-*- but to leave no doubts in this respect the following 



experiments were made. 



y 2 



