Febi-uary 25. 1917 



HARDWOOD RECORD 



19 



is sometimes Tery hard, polished steel ball of a size agreci upon. iNat- 

 uraUy, different woods have varying degrees of hardness. The greater 

 the hardness, the more force is required to drive the point to the 

 specified depth. 



Nearly forty years ago a list of 300 American woods, showing the 

 relative hardness of each, was prepared for the government. The 

 comparative hardness of the different specimens was shown by the 

 series of numbers from 1 to 300. No 1 was the hardest (lignum vitae) 

 and No. 300 the softest (gumbo limbo) and all others came between. 

 Every wood in this list below 42 is a broadleaf species. The hardest of 

 the needle-leaf trees — the softwoods — is pond pine, a rather inferior 

 •tree which is met with on the south Atlantic coast of the United States. 

 Its number is 42 in the list referred to. Forty-one broadleaf trees ex- 

 ceed in hardness the hardest of the needle-leaf trees. From 42 to 300 



s rr«tAxvv£i-t- 



WOODEN GLUTS FOR SPLITTING TIMBER 



in the list, the softwoods and hardwoods are weU mixed, when ranged 

 in regard to hardness. 



In a list of our twenty hardest woods, seventeen come from Florida 

 and three from west of the Eocky Mountains. This list may be of 

 interest and it is here given, though not one of the twenty, except lig- 

 num vitae, is ever heard of in shop and factory, and the lignum vitae 

 in use here does not grow in this country but is imported. 



The Twenty Hardest U. S. Woods 

 Rank in 



Hardness 



Lignum vitse 1 



Sonora ironwood 2 



Black ironwood 3 



Red ironwood 4 



Cinnamon bark 5 



Torchwood 6 



Princewood 7 



Mangrove '. .S 



Red stopper 9 



Rocky Mountain blue oak 10 



Rank in 

 Hardness 



Emory oak 11 



White stopper 12 



Pigeon plum 13 



Florida plum 14 



Satin leaf 15 



Wild sapodilla 16 



Douglas oak 17 



Satin wood 18 



Florida button wood 19 



Gurgcon stopper 20 



It is not improbable that some of these extremely hard woods might 

 make shuttles, but it does not appear that anyone has ever tried them 

 out. Most of them occur as trees of inferior form and size. 



It may be of interest to compare the twenty softest woods of the 

 United States with the twenty hardest named above. The softest fol- 

 low, ranging from No. 281 to No. 300. 



Twentt Softest U. S. Woods 



Rank in 

 Hardness 



Sitka spruce 281 



Yellow buckeye 282 



White spruce 2S3 



Western red cedar 2S4 



Pawpaw 285 



California big tree 286 



Southern white cedar 287 



Idaho white pine ' 288 



Eraser fir .... .289 



Rank In 

 Hardness 



Balm of gilead 291 



Lovely fir 292 



Black Cottonwood 293 



Alpine fir 294 



Largetooth aspen 293 



Golden fig 296 



-A^rborvitse 297 



Downy Cottonwood 298 



Grand flr 299 



Gumbo limbo 300 



Common basswood 290 



So far as figures are available, the foregoing are the softest woods 

 of this country; but we have data on only 300 species, leaving nearly 

 that many which have never been tested. Probably woods both harder 

 and softer than those here given will be found when aU American 



-species have been tried. The list of twenty softest woods contains sev- 

 eral of great importance, both needle-leaf and broadleaf, as weU as 

 some which are of little account. 



Hardness op Various Woods 

 Oaks are all hard, but the different species vary. Three unimpor- 

 tant ones are included among the country's twenty hardest. There 

 are fifty-two oaks in the United States and the following list names 

 ten, all of which are or have been important in the country's indus- 

 tries. Beginning with the hardest, southern live oak, they range: 



Rank in 

 Oaks Hardness 



Southern live oak 30 



Texas red oak (spotted oak) .... 44 

 Overcup oak (Forked-leaf oak). 72 



Bur oak 82 



Cow oak 83 



Rank in 

 Hardness 



Shingle oak 89 



Willow oak 102 



White oak 105 



Yellow oak 115 



Red oak (northern) 150 



Sycamore and yellow birch differ little in hardness. Pignut hickory 

 and dogwood are nearly the same. Red gum is about like paper birch. 

 Black walnut and white ekn differ little. Mahogany is harder than 

 hickory, not so hard as persimmon, but much harder than any of the 

 birches. 



Hardness Influences Use 



While wood is employed for many purposes where its hardness or 

 softness is not specially considered because the requirements are not 

 exacting, there are many other uses which are largely determined by 

 a wood's hardness or softness. For example, a wood too soft is not 

 suitable for railroad ties, because the rails cut into them, and the 

 wallowing of the tie in the bed of ballast wears the wood out before it 

 becomes useless through decay. Ties of that kind will last longer 

 if steel plates fit between the rail and the wood. 



Wood 's hardness is highly valued by floor makers. Actual tests have 

 shown that a maple floor outwears marble, where conditions are similar. 

 Floors of birch and beech are nearly as durable, while oak compares 



WOODEN ROLLER WAY FOR LOADING LUMBER AT DOCK 



favorably with the best, and longleaf pine 's hardness assures excellent 

 wearing qualities. The popularity of black gum and cotton gum for 

 factory and warehouse floors is due less to hardness than to the inter- 

 laced fibers which under heavy wear become a felted surface which is 

 little inclined to scratch or splinter. The same quality gives teak its 

 high value for ship decks; the broomed fibers convert the surface into 

 a wearing mat. Teak is not an exceptionally hard wood. 



The wooden rollers used in sawmills for off-bearing the lumber, and 

 on docks and landings for loading and unloading boats with timber and 

 lumber, are made of the hardest woods procurable, maple, birch, beech, 

 hickory, locust, mesquite, and persimmon. These woods are likewise 

 preferred for the large rollers used by house movers. Unless very 

 hard, the rollers are soon frayed or crushed. 



Before the days when it was customary for sleds to be shod with 

 steel, the rural maker selected his sled soles from the hardest woods 

 within reach, each region having one or more that were excellent. The 

 rollers above referred to had to sustain a crushing, grinding force ; but 

 the sled sole glided along and was worn out by incessant scraping, and 

 it was required to present a hard, smooth surface. Hickory, hornbeam, 

 dogwood, persimmon, sourwood, and white oak were preferred when ob- 

 tainable. The wearing qualities of hickory surpass any other wood 

 when it must resist rubbing in the direction of the grain, as in a sled 



