ee 
O44 INDUSTRIAL PLANTS 
stiffness through considerable length together with lightness 
are most important. 
Vehicles, in their running parts, require great toughness 
together with elasticity in order to meet the very severe 
and frequent shocks and wrenchings to which they are sub- 
jected; while on the body lightness and stiffness are especially 
desirable. 
Fic. 228, I1.—Willow. A, pistillate flower-cluster. B, staminate fiower. 
enlarged. C, same, cut vertically. D, pistillate flower, enlarged. 
E, pistil, cut vertically. F, seed, entire. G, same, cut vertically. 
(Baillon.) 
Harness though made mostly of other material may con- 
sist largely or wholly of wood, as with certain saddles, stirrups, 
hames, and yokes; and then, as being subject to much the 
same strains as parts of vehicles, needs scarcely less stiffness, 
lightness, and elasticity than they. 
Road materials, including wooden pavements and railway 
ties, require blocks or logs of exceptional strength and dura- 
