588 THE POPULAR SCIENCE MONTHLY. 



ing, and is usually considered by millwrights as next to hornbeam, 

 both in strength, toughness, and general suitability for that purpose. 

 It requires, however, to be kept very dry, for in damp situations it 

 quickly wears out, but, when beech is immersed in water constantly, 

 its endurance is considerable. The strength of beech is nearly the 

 same as that of oak ; it is also tougher, but its stiffness is inferior to 

 that of oak, even to the extent of 25 per cent. 



Elm, although a cross-grained, rough wood, and mostly used for 

 rough purposes, is yet held in great estimation for its toughness and 

 non-liability to split by the driving of bolts. It is much used in the 

 construction of blocks for pulley-tackle, for heavy naval gun-carriages, 

 and for the naves of carriage-wheels. It is a wood which is little af- 

 fected by constant immersion in water, but decays rapidly when alter- 

 nately wet and dry, and consequently is not very durable for purposes 

 involving exposure to a wet climate. Its chief defect in ordinary use 

 is its great liability to warp, and twist, and get out of form ; and, as 

 regards strength, toughness, and rigidity, it is inferior to oak, as well 

 as in almost every other respect. 



The fir and pine woods are members of a large family, and are of 

 great variety, and differ much in most of their properties. These 

 classes of timber, in addition to being employed for building purposes, 

 are likewise the chief materials that are used in great works, where the 

 question of strength combined with cost becomes the most prominent 

 consideration. The most durable varieties are the larch, the pitch- 

 pine, and the firs, from Memel and Norway, and are valued mostly on 

 account of the large quantity of resin, pitch, and turpentine, which 

 they contain. The Canadian pine, variously termed white or yellow, 

 is not a strong wood, but is much used by engineers for making pat- 

 terns or models, on account of its smoothness of surface, its non-liability 

 to warp, its comparative freedom from knots, and the facility with 

 which it can be cut. The white or yellow pine is not nearly so strong 

 or so stiff as oak, yet sometimes it is almost equal to it in its tenacity 

 and toughness. In such a large family as that of the resinous firs and 

 pines, there is almost an equal variation in their strength, toughness, 

 and rigidity. 



Hornbeam is a wood which is comparatively little used, except by 

 engineers, for the teeth or cogs of wheels, and for mallets, for which 

 purposes it is perhaps superior to all other woods, and this is mostly 

 due to its great toughness and remarkably stringy coherence of fibre. 

 Its cohesive strength and other properties depend much upon its age, 

 as a plank, and still more on the age of the tree from which the plank 

 was taken. When in the most favorable condition, it is fully equal to 

 the average of oak (even when considered merely as a wood), but 

 when cut from older trees, and when over-seasoned, it is frequently 

 found worthless, and has soon to be renewed. When of proper age 

 and quality, it has no equal for its own special purposes. 



