FOKESTRY. 641 



Strength of packing boxes of various woods, W. K. IIatt ( r. S. Dcpt. Agr., 

 Forest Scrr. Cirr. .'/7, /)/>. N. /i</x. -O.— The merits of Michigan wliite pine, New 

 England wliite pine, loblolly pine, western spruce, western hemlock, cottonwood, 

 and red gum as box material were tested. 



The lumber used was of average (lUiUity. containing al)()Ut 14 per cent mois- 

 ture with only sound, live knots, and without sap stains. Three sizes of boxes 

 were made up — large, holding up to about 6(X) lbs. of dry goods; medium, corre- 

 sponding to those used for hardware, soap, or canned goods, up to 2.10 lbs., and 

 sni:ill. holding up to 1(K) lbs. Four styles of boxes were also used, (1) i)lain 

 without battens, (2) four square battens on each end, (3) four bevel battens 

 on each end, and (4) two battens on each end. In testing, the load was applied 

 along the diagonal of the box, an action similar to that which occurs W'hen the 

 box is dropped on one of its corners. In case of small boxes the load was also 

 applied along the entire length of the edge of the box. 



The results of the tests show that of the woods tested " cottonwood was the 

 strongest for medium and large boxes and red gum for boxes of small size. 

 l'\)r all sizes cottonwood and red gum occupied the first two positions in regai'd 

 to strength. The weakest Avood differed for each kind of box. For the large 

 size it was western spruce, for the medium size INIichigan white pine, and for 

 the small size North Carolina pine." When, however, the .strength of the 

 boxes Iter unit of weight was considered the cottonwood as before stood first, 

 white pine standing second for boxes of large size. For small size, however, 

 cottonwood, r(Hl giun, western spruce, and western hemlock showed greater 

 strength than white i)ine. 



The experiments also showed that thin end boards could not be substituted 

 for end boards of standard thickness without reducing the strength of the box. 

 \Vith small boxes of New England pine the strength of lock-cornered boxes 

 exceeded that of dovetailed boxes, while the latter were stronger than nailed 

 boxes. Other tests showed that the majority of nails at the end of the side, 

 top, and bottom boards should be driven into the end boards rather than into 

 the battens. 



Kiln-drying hard-wood lumber, F. Dunlap (T. S. Dept. Afjr.. Forest Serv. 

 Cire. .'fS. pp. 19. fills. '/). — The author describes the systems of kiln-drying hard- 

 wood lumber generally in vogue in this country, discussing at considerable 

 length the theory of drying, and points out a number of unsolved problems in 

 this industry. The report is based on work with white oak, red oak, ujajtle, 

 birch, basswood, chestnut, ash, red gum. mahogany, cherry, and walimt. 



It was found that the time consumed in kiln-drying these woods varies greatly 

 among different opei'ators. White oak, for instance, is generally dried from 1 to 

 2 weeks, yet some operators doulde this period, and others reduce it to from 3 

 to .5 days. The length of time thiit each species should be dried varies widely 

 with a luimber of conditions. Thus " (juarter-sawed oak iisually reipiires 

 half again as long as plain oak. m.-iiiogany requires about the same time as ])lain 

 o.ak. ash dries in a little less time, and maple, according to the purjwse for 

 which it is intended, may be dried in one-fifth the time needed for oak. or 

 may lu'ed a slightly longer treatment. For birch the time re(|uired is from 

 one-half to two-thirds and for poplar and basswood from one-fifth to one-third 

 as long as that required for oak." 



The cost of kiln-drying among different operators was found to be from 

 75 cts. to $5 per thousand feet. 



It api)ears from the investigations that dry kilns are constructetl and operated 

 at the present time largely without careful system. Many of the [tresent 

 defects in kiln-drying resulting in warping, twisting, checking, case-hardening, 



23577— No. 7—07 i 



