HARDWOOD RE CORD 



33 



l.urn more slowly, furivish a good bed of live eoals and exceed the 

 former by from 25 to 30 per cent in production of heat with ordinary 

 appliances. 



. The amount of heat -nhieh escapes up the chimney with different 

 • onditions of draught varies greatly. Carbon often escapes uncon- 

 sumed in the fonu of smoke. Pine, although capable of yielding 

 more heat than oak, may in practice yield less, the smoke of oak 

 being almost entirely consumed, Trhile in pine a portion of the carbon 

 and hydrogen may escape in the smoke. In burning fat pine under 

 a boiler the flashy nature of the heat causes serious contraction and 

 expansion of the flues and other parts, which renders its use for such 

 purpose undesirable in spite of the total large amount of heat it is 

 capable of producing. 



Suppose it is desired to know the comparative heating values of 

 wood and coal. To solve such a problem accurately it is necessary to 

 have at hand definite information as to the kind and weight of wood 

 and the percentage of moisture contained; also the kind of coal with 

 which its efficiency as a fuel is to be compared. The weight of dry 

 wood is subject to great variation not only in different species but 

 also in different pieces of the same species. Any figure given must 

 be approximate averages only. 



Table of Weights of Kiln-Dried Wood. 



1. Very heavy: Wt. per eu. f t. Wt. per cord. 



Hickory, oak. black locust, blue beech, 



hackberry and white ash 42-48 lbs. 3200-4000 lbs. 



2. Heavy : 



' Elm. cherry, birch, maple, beech, wal- 

 nut, best of longleaf pine and tam- 

 arack 36-42 lbs. 2800 3200 lbs. 



3. Medium : 



Southern pine, tamarack, Douglas fir, 

 western hemlock, red gum, red maple, 

 sycamore, sassafras 30-3G lbs. 2400-2800 lbs. 



4. Light: 



Norway pine, western yellow pine, red 



cedar, cypress, redwood, basswood... 24-30 lbs. 2000-2400 lbs. 



a. Very light : 



White pine, spruce, fir. white cedar, 



Cottonwood 18-24 lbs. lDOO-2000 lbs. 



The preceding table gives weights of dry wood only. Before apply- 

 ing them the water content must be added to comply with the actual 

 conditions. It must also be remembered that there are many factors 

 affecting the solid contents of a cord, such as the length, diameter, 

 smoothness, straightness, and method of piling of the sticks, so that 

 the 128 cubic feet by outside measurement rarely contain more than 

 90 cubic feet of wood, and sometimes as low as 50. 



The amount of heat a pound of average dry wood will furnish 

 under good conditions is not less than 8,000 thermal units. A poand 

 of good bituminous coal will furnish about 14,000 units, making the 

 drj- wood about 57 per cent as efficient as the coal. If the wood 

 contains 25 per cent moisture the comparative efficiency of the wood 

 would be the ratio of 7,723 (8,000 — 277, as previously stated) to 

 14,000, or about 55 per cent. For any other moisture content the 

 calculation can be readily made as stated above. 



With comparative values on the basis of equal weights, and knowing 

 the average weight of a cord, it is very easy to calculate the com- 

 parative efficiency of a cord of wood and a ton of coal. Thus, if the 

 weight of a cord of wood at 25 per cent moisture is 2,500 pounds, 

 nearly a cord and a half will be required to equal a ton of coal. In- 

 stead of using the figures given in the table, it would be much better 

 to measure and weigh several average cords of the actual material to 

 be tested. The amount of moisture can be determined by comparing 

 weights of samples of the wood before and after thorough drying in 

 a kiln. 



It might prove interesting to compare these results with those ob- 

 tained by actual boiler tests. On logging engines a ton of good 

 grade bituminous coal is considered equivalent to a cord and a half 

 of air dry oak or two cords of softwood. Two and a half cords of 

 pine knots (about 125 cubic feet) are considered to furnish about 

 the same amount of steam as one ton of southern soft coal. For gen- 

 eral calculations for stationary engines one ton of coal is considered 

 equivalent to two cords of wood, or one pound of coal to two and a 

 quarter pounds of wood. Wood requires about one-third more grate 

 surface and two-thirds more cubical space than coal for generating 

 an equal amount of steam. It will be seen that these figures give 

 comparatively lower values for wood as fuel, which is probably due 

 to the fact that it is not the actual heat producing power of the 



fuels that is compared but the efficiency of the apparatus for utilizing 

 this heat. 



The best all-round fuel wood in this country is hickory, and in the 

 eastern markets it is especially in demand for burning in open fires. 

 The retail .price of seasoned hickory of good quality is $11 per cord 

 iu New Haven, Conn. The price there for mixed hardwoods cut into 

 stove lengths and delivered is from $8 to $9 per cord. These prices 

 are out of proportion to the heating value of wood as compared to 

 coal, but wood is desirable for fires of short duration in the late 

 spring and early fall when the mornings and evenings may be too 

 chilly for comfort, before the regular heating apparatus has been 

 started. There is no real substitute for wood in fire places and 

 grates. 



Chestnut, butternut, and to some extent tamarack and spruce are 

 in ill favor for open fires owing to their crackling and emission of 

 sparks. Many woods are diflScult to split and therefore hard to sea- 

 son, reducing their desirability for fuel. When old elms are removed 

 from the parks and city streets in the East there is little demand for 

 the material for fuel because it is so tough to split; the sawmill 

 owners object to it because of the danger to their machinery from 

 hidden pieces of iron and other foreign substances. In parts of the 

 South pine knots and old snags of trees rich in rosin are in great 

 demand for kindling purposes and not infrequently are relied on to 

 furnish light as well. Birch contains a peculiar substance known as 

 betulin which adds to its heating power. 



In the southern part of Arizona, where there is little utilization of 

 timber except for fuel, a strong prejudice exists against the use of 

 certain woods for this purpose. Arizona while oak is held to be a 

 very inferior fuel wood as compared to the local black oak. Some 

 tests made by the IT. S. Forest Service showed that for average sam- 

 ples the heating value in the black oak is only about ten per cent 

 greater than that in the white oak. The greatest difference in heat- 

 ing value in the two oaks occurs in the bark, that of black oak being 

 about twenty-eight per cent higher than that of the white. The ash 

 from an average butt cut sample was about twice as much in the white 

 as in the black. 



In Douglas fir and western yellow pine the bark has a higher heat- 

 ing value than the other parts of the tree. In the Northwest Douglas 

 fir bark is often a principal source of fuel in firing donkey engines. 

 The bark of the shagbark hickories has a high fuel value, burning 

 with intense heat but with much crackling. In many woods, particu- 

 larly the cedars, the bark has a comparatively low fuel value and 

 leaves a large proportion of ash. 



Root wood is usually considered of little use for fuel. It is inter- 

 esting to note, however, that the roots of mesquite are capable of pro- 

 ducing more heat than the average butt cut, and it is a common cie- 

 tom to dig them up for fire wood. "Very often mesquite roots are so 

 much more developed than the rest of the tree that the name ' ' under- 

 ground forests" has been applied to stands of the timber in semi-arid 

 regions. 



It is unusual to find woods which have their value for fuel affected 

 by the odor they give off. In the Southwest there are a few; for ex- 

 ample, the horse bean and the palo verde, which emit very penetrat- 

 ing, disagreeable fumes when burned, thus reducing materially their 

 desirability for fuel even in a region where wood is scarce. 



S. J. K. 



How Ties Should Be Laid 



If two railroad ties are made from the same log, which side should 

 be placed on the ground, the tangential or outer side of the growth 

 rings, or the radial or heart side? The latter appears to be the 

 common practice, but there is good reason for believing that the life 

 of a tie can be increased by laying it differently. 



The presence of season checks in wood allows water to penetrate 

 it and facilitates the entrance of rot-producing fungi. Wood shrinks 

 in a tangential directiou twice as much as it does radially, and as a 

 result splits from the outside of a log inward. If the tie is placed 

 with the heart side down these splits remain exposed to the rains and 

 invite disease, while if reversed the water would drain off readily and 

 the season checks would partially close up. 



