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SYLVA FLORIFERA. [ADDEND. 



Experiments on the Resilience of Timber. 



The pieces were each an inch in depth, and laid upon supports 

 thirty inches apart. The weight fell between two vertical guides 

 (similar to a pile engine), upon the middle of the piece. 



No. of 

 Exper. 



Description of 

 Timber. 



Breadth 

 of the 

 Piece. 



Weight. 



Height from 



which the 



Weight fell. 



Effects. 



No. 7. 



Oak, same kindl 

 as No. 4. J 



1 inch. 



7 lbs. 



48 inches. 



Broke. 



No. 8. 



Larch, same kind \ 

 as No. 2. ) 

 The same 

 The same 

 The same 



The same 



The same, convex") 

 side upwards J 

 The same 



1 inch. 



7 lbs. 



48 do. 



54 do. 



60 do. 



^66 do. 



72 do. 



72 do. 

 42 do. 



No effect. 



No effect. 



Set to a slight curve. 



A little more curved. 



( Curved about an 



\ inch. 



C Curved the con- 



( trary way. 

 Broke. 





















14 lbs. 





No. 9. 



Larch, same kind ) 

 as No. 3. 3 

 The same 



0'8 inch. 



7 lbs. 



48 do. 

 54 do. 



No effect. 

 Broke. 







No. 10. 



Oak, same kind! 

 as No. 5. J 

 The same 



1 inch. 



7 lbs. 



48 do. 

 54 do. 



No effect. 

 Broke. 







No. 11. 



English Oak 

 The same 



1 inch. 



7 lbs. 



54 do. 

 60 do. 



No effect. 

 Broke. 







No. 1 1 was a dark-coloured and apparently very strong piece 

 of wood ; specific gravity 0.872 or 54^ lbs. per cubic foot. * On 

 the whole, then, it appears, that Larch is superior to oak in 

 stiffness, in strength, and in the power of resisting a body in 

 motion (called resilience) : and it is inferior to Memel or Riga 

 timber in stiffness only. 



I am, Sir, yours, &c. 



THOMAS TREDGOLD. 



Grove End, March 16, 1818. 



* These experiments were made in the presence of His Grace the Duke of 

 Atholl, Lord Prudhoe, Lord James Murray, John Deas Thomson, Esq., William 

 Adair, Esq., Mr. Geo. Bullock, and Mr. Atkinson, architect to the Ordnance. 



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