HARDWOOD RECORD 



Resolved, By 

 ment & Vehicle 

 ber Association. 



committee, 

 utacturers' 

 Hardwood 



representing Jointly the National Imple- 

 Association, the National Hardwood Lum- 

 Manufacturers' Association of the United 

 od Jlauufacturers' Assoiiation, and the 



plus reasonable profit for the hardwood materials necessary for govern- 

 ment vehicle contracts, or to submit the matter to proper price-fixing 

 powers of the government. 



The foregoing resolutions unanimously adopted and signed this 26th 

 day of June, 191S, by the following committee : 



[Signed] 

 H. M. Kinney, 

 F. H. Gluesing, 

 W. B. Swift, 

 Representing the National Implement & Vehicle Manufacturers' Asso- 



J. W. McClure, 

 F. W. Mowbray, 



HoGH McLean, 

 Representing the Hardwood Industry. 



Foreign Woods for Airplane Propellers 



Woods Used and Those That Gin Be Used, and Methods of Identification 



Samuel J. Record 



Airplane propellers are divided into two main types, according 

 to their use for training planes or combat planes. The former are 

 smaller, are used with motors of not over 110 horsepower, have rela- 

 tively low speed and accordingly are not so exacting in the woods 

 used. In the combat type with motors of 400 horsepower, speeds 

 up to 150 miles per hour or more, and the very severe field service, 

 the greatest discrimination is made in the choice of material used 

 and few species are now acceptable. Perhaps when more is learned 

 about some of the tropical woods now little exploited the list can 

 be very materially increased. 



The woods now used for training propellers are quartered white 

 •oak, Philippine mahogany, cherry, birch, black walnut, and some- 

 times yellow poplar. For the combat types the species are true 

 mahogany from tropical America, African mahogany, quartered 

 white oak and black walnut. 



There are a great many woods which appear on the market as 

 mahogany, but the term ' ' true mahogany ' ' is reserved for species 

 of Swietenia. There are at least two species growing in tropical 

 America, namely, Swietenia mahagoni and S. maofopliylla. It is 

 likely that other species will be recognized when the botanists make 

 a closer study of them. Most of the mahogany now being used for 

 propellers is probably from the large-leaved species, S. macrophylla, 

 which usually has a softer and lighter wood than the other. 



The range of mahogany extends from the southern tip of Florida 

 through the West Indies, along the northern coast of South America 

 (Guiana, Venezuela and Colombia), throughout Central America 

 and into southern Mexico to a line running south from Tampico. 

 Owing to the great diversity of conditions under which the tree 

 grows it is not surprising that there are equally great variations in 

 the quality of the wood. The differences are as pronounced as 

 between the extremes of the southern pines. The writer recently 

 made some specific gravity determinations of mahogany used for 

 propellers, which show a range from .380 to .737, based on oven-dry 

 measurements. Of five average samples the range was from .426 

 to .460. There is an equally great range in color, some being very 

 light, either yellowish or pinkish, some salmon-colored, some deep 

 maroon. Some is straight-grained, some cross-grained, some ribbon- 

 grained. The harder and heavier specimens are often streaked with 

 small white lines on account of the pores being filled with lime. The 

 cabinet qualities vary also, some of the softer grades being woolly 

 and likely to tear out, and at the other extreme a hard, brittle 

 material. 



These difEerences in quality and physical characters are not deter 

 mined by the particular country from which the material is obtained, 

 although in a general way there are certain geographical distinc- 

 tions. Nor are the difEerences due entirely to the species. Eather 

 it is the quality of the site and soil and climate and this may change 

 decidedly within a very short range. "Wood from slow-growing 

 trees on high, dry ground is mostly hard and strong, while that 

 from rapid-growing trees in moist lowlands is mostly soft and 

 spongy. The latter grade is often termed "baywood" or "bay 

 mahogany" and is most common along the coast of southern Mexico. 



The material coming from the West Indies is mostly heavy, hard 

 and cross-grained, while that from Colombia and Venezuela is 

 inclined to be crooked, knotty, dotty or otherwise defective, so that 

 the main supply of mahogany for propellers is coming from Central 

 America and southern Mexico. 



No one knows how much mahogany timber is standing in these 

 countries, since no systematic attempt has been made to find out. 

 Much of the most accessible and choice timber has been cut, but 

 farther back from the coast and the navigable streams there are 

 still enormous quantities to be had, partly in good stands and partly 

 scattered over large areas. Such rough estimates as are available 

 indicate the following total stand by countries: Southern Mexico, 

 15 billion board feet; British Honduras, less than 100 million feet; 

 Guatemala, less than 750 million feet; Honduras, about one and 

 three-quarter billion feet; Nicaragua, about one and one-half billion 

 feet; Costa Rica, about 250 million feet; Panama, less than 100 

 million feet, making a total of nearly 19^4 billion feet, of which 

 three-fourths is in southern Mexico, a region poorly exploited. 



Not all of the timber imported from tropical America as mahogany 

 is genuine. Some of the grades of Spanish cedar are as heavy as 

 the medium and light grades of mahogany and are sold for it. The 

 Spanish cedar {Cedrela spp.) is not akin to the woods we know as 

 cedar, but is so called because of its fragrant odor. Sometimes 

 this odor is very pronounced, as in the ease of the best cigar-box 

 wood, but in the grades which most closely resemble mahogany it 

 may be so mild as to escape notice. The writer has examined a 

 large number of pieces of the supposedly odorless varieties and has 

 yet to find a fresh specimen without some characteristic fragrance. 

 In fact, this is the only character which he knows of, vnth our 

 present limited knowledge of these woods, which can be always 

 used to separate certain types of cedar from certain kinds of 

 mahogany. The two woods are closely related, and it seems likely 

 that the best grades of cedar would serve the same purposes as 

 mahogany of the same weight. The Colombian mahogany (Carini- 

 ana pyriformis) belongs to a different family and offers no special 

 difficulties in the matter of identification. 



Africa supplies a number of woods known to the trade as 

 mahogany, but the real African mahogany is supposed to come 

 from a tree very closely related to the American genus and known 

 botanically as KJwya senegalensis. But here, as with our mahogany, 

 there is some question as to species. The tree grows over a vast 

 stretch of tropical Africa from the Atlantic to the Indian Ocean. 

 The principal sources of supply are the countries bordering the 

 Gulf of Guinea, though it is very common along the Gambia river 

 and the region of Cape Verde. Hence the English name of Gambia 

 mahogany. Commercial plantations of the tree have been made by 

 the French in Senegal. It is also being propagated in Trinidad 

 and will probably prove a valuable tree for various parts of trop- 

 ical America. 



The true African mahogany supplies a wood of excellent quality, 

 and tlie material coming into our markets shows less variation than 

 (Continued on page 3 'a) 



