RICVIKWS iJ81 



feet long and 3 feet in circumference (called bavins). The cost of 

 cutting and stacking firewood is given as 7 shillings per cord, and of 

 making faggots 4 shilling G pence. 



Some data are given on comparative values of different woods for 

 heating purposes, together with notes on their manner of burning. 

 No attempt is made to express these values numerically. It is stated 

 that "heating properties of wood depend mainly on the amount of 

 carbon that is contained in the woody fiber, as also the presence of 

 oil or resin. To a large extent, therefore, the density of tissue and 

 nature of its contents will determine the heating properties of our 

 home-grown woods. . . . Age, soundness, amount of moisture 

 contained, as also the presence of oil or resin, have all much to do in 

 determining the heating power in proportion to the specific gravity of 

 the particular wood." 



Home-grown woods are divided into three classes according to heat- 

 ing power (on another page into four classes). These are: (1) Of 

 greatest value : yew, hornbeam, thorn, oak, laburnum, hazel, laurel, 

 beech, resinous old pine; (2) of medium value: apple, pear, ash, 

 acacia (Robinia), birch, elm, maple, evergreen oak, sycamore; (3) of 

 little value : lime, alder, horse chestnut, willow, spruce, poplar, larch, 

 most of the pines. The average weight of a cord of mixed hardwoods 

 is given as 3,100 pounds green and 2,100 pounds dry, and it requires 

 fully 2^ tons of the best firewood (seasoned oak) to equal one ton of 

 coal, so that "except for fire-lighting, the use of wood as a fuel in this 

 country may, unless in the case of private estates, be looked at in the 

 way of a luxury, the heating properties of even the heaviest or most 

 resinous timber being far behind that of coal, while the expense of 

 preparation is proportionately great." 



A considerable part of the book is given to description of the 

 method of making charcoal and discussion of its use for fuel and for 

 making gunpowder. The army required great quantities for heating in 

 the trenches where smoke was undesirable. Fair quality charcoal is 

 made from the "black alder" or "dogwood." Rhamus frangula, a shrub 

 or small tree native to southern England, which is cultivated for 

 gunpowder charcoal in much the same way osiers are grown. Planta- 

 tions are started from seed or by layering, an J managed as coppice, 

 cutting every six or seven years. Returns are much higher than from 

 ordinary coppice timber. (Might it not be worth while to investigate 

 the possibilities of some of our American species of Rhamus for pro- 

 ducing high-grade charcoals?) The black alder wood contains 27 per 

 cent of charcoal (presumably by weight, though the author does not 



