PRUNING SHRUBBEBIES. 419 



"The two pieces were squared down each to two inches. 

 They were hroken on props fifty inches asunder. Their 

 specific gravity, elasticity, and ultimate and comparative 

 strength, were as below : — 



„ „ „ Deflected 1.50tli of its Broken with Comparative 



Spec. grav. length with BroKenwitn strength. 



No. 1. 903 660 lbs. 999 lbs. 1561 



No. 2. 856 414 lbs, 677 lbs. 1058 



"No. 1, it appears, is therefore ahout of medium strength, 

 my mean number being for English Oak 1470. No. 3 is very 

 weak, my weakest specimen being 1205 (see Essay on Strength 

 of Timber). We tried, besides, two very choice specimens of 

 English Oak which had been very long in store, and the 

 numbers were. 



Spec. grav. Deflected l-50th with Broken with Comp. Btr. 



748 896 lbs. 1447 lbs. 2261 



756 680 lbs. 1304 lbs. 2037 



" These again, compared with your weakest piece, show that 

 your No. 1 is about the common run of English Oak." 



Another experiment upon strength gave exactly the same 

 result. These are incontrovertible proofs that, cceteris paribusi 

 the fastest-grown Oak is the best ; and it may be added that all 

 evidence goes to show that what is true of the Oak is true of 

 other trees. 



Few remarks are called for as regards the pruning of shrub- 

 beries. The knife is only wanted there to thin the branches 

 so as to prevent them from dying from want of light and air, or 

 to shorten them so as to prevent the shrubbery becoming naked 

 at the bottom. Winter is the season in which the operation is 

 best performed ; September and October are the worst months, 

 because the buds of pruned shrubs are apt to br§ak after the 

 last of those months, and the young shoots have not time to 

 ripen. Even midsummer pruning will in damp autumns 

 produce the same disadvantageous result. Nevertheless there 

 are those who advocate autumn pruning for all Evergreens. It 

 is alleged that when Evergreens are cut back in the autumn, 

 the roots, which are not affected by the pruning, continue to 

 absorb during the whole winter, and to render all the mutilated 

 branches turgid with sap against the return of spring; the 



£ E 2 



