August 1, 1919.] 



THE INDIA RUBBER WORLD 



627 



test. The drum is a hexagon-sided machine and revolves slowly. 

 The box is packed with the actual contents, as in commercial 

 service, and placed in this drum. In the drum are arranged a 

 series of hazards, which cause the box to follow a regular cycle 

 of drops, falling upon sides, top, bottom, ends, edges, corners, 

 and flat-wise upon a projection similar to the corner of another 

 box. These drops simulate the usual hazards of transportation, 

 excepting the heavy static pressure received by a box in the lower 

 tiers of a pile, which is secured by means of the compression-on- 

 edge test previously described. 



As the box moves on from one drop to the next the observer 

 notes the beginning of the failure of the weakest point in its con- 

 struction and follows the development of that weakness until 

 the box entirely fails and lets its contents out. 



The weak feature of the box may be too few nails, nails of 

 too short a length, nails driven in a crack and thus having no 

 great holding power, or some other form of nail failure; and the 

 tests clearly show this weakness. The material in the sides, top. 



Testi.xg Lamp Containers in Six-Foot L>ki m. 

 or bottom may be torf thin, so that the shocks of the falls pull 

 the wood from the nails. The wood may split or break across 

 the grain. 



Any one of the numerous weaknesses of packing-box con- 

 struction may be developed in this test until finally the observer 

 is able to build up a box that is practically equally strong in every 

 feature. Boxes are then built, packed, and tested until the pres- 

 ence of this balance in design is clearly demonstrated. Such a 

 demonstration will show failures ultimately occurring in average 

 proportion in nails pulling from the wood, wood pulling from 

 the nails, splitting or breaking of ends, sides, tops or bottoms, 

 and through the weaknesses of the species themselves. 

 AIDS IN BOX DESIGNING. 



As a result of many box tests no general rules can be laid 

 down, for the reason that each box must be built with reference 

 not only to the external shocks it will have to endure, but also 

 to the nature of the article it is to contain. 



QUALITY AND CONDITION OF LUMBER. 



Boxes should be manufactured from lumber which is sound, 

 free from decay and dote, and well-seasoned. The average 

 moisture content of the wood should be from 12 to 18 per cent, 

 "based on the weight after oven-drying. 



The effect on the strength of the box caused by the moisture 



condition of the lumber and the change of moisture condition in 



storage is very marked, the strength relation showing a variation 



in the holding power of the nailing from 10 to 100 per cent. 



INTERCHANGEABILITY OF SPECIES COMMONLY USED 



FOR BOXES. 



The results of the drum tests have made it possible to divide 

 the kinds of wood generally used in packing boxes into the four 



groups shown in the following table. Thus, any wood in one 

 group substituted for any other wood in the same group and 

 built into a box of the same specifications would give practically 

 the same results in commercial service. 



Group 1. 

 White pine . 

 Norway pine 



Sp™« ".'.'.'.'. 

 Western yelh 



Balsam fir 

 Chestnut 

 Sugar pins 

 Basswood 

 Cypress .. 

 Willow .. 

 Noble fir 

 Magnolia 

 Buciceye . 

 White fir 

 Cedar ... 

 Redwood 

 Butternut 



Alpine fir 



Hemlock- 



and 



Carolina pine. 

 Douglas fir . . . 



Larch 



Group III. 

 White elm ... 

 Red gum 



.011 I .0085 

 .0096 .0072 

 .011 I .008 



Black 

 Tupelo 

 Maple, 



Hard maple 



Beech 



Oak 



Hackberry 



.0067 .0054 



.0049 

 .0051 

 .0051 

 .0053 

 .0052 

 .0052 

 .0053 



.0064 

 .0064 

 .0067 

 .0053 

 .0062 

 .0065 

 .0055 



Weights Given in Pounds Per Square Inch Surface Measurement for 



Usual Packing-Box Thickness. Species in Air-Dbied Condition 



12 TO 15 Per Cent Moisture Content. 



DETAILS OF CONSTRUCTION. 



THICKNESS OF LTIMBEE. 



Where woods in Groups I and II are H-inch thick or less, 

 woods in Groups III and IV can be 1/16-inch less in thickness; 

 where woods in Groups I and II are more than ^-inch thick, and 

 not more than 1-inch, woods in Groups III and IV can be '-^-inch 

 less in thickness. 



WIDTHS OF LUMBER. 



No piece less than 2H inches face width should be used in 

 any part except cleats. Any part of a box which is 6 inches or 

 less in width should be made in one piece. 

 JOINING. 



All parts which are of two pieces or more should be tongued 

 and grooved, except ends, which may be butt-jointed and fastened 

 with not less than three corrugated fasteners, two driven from 

 one side and one from the opposite side, or cleated. Cleats 

 should be not less than two inches wide and the same thick- 

 ness as the sides, tops and bottoms. 



NAILS. 



The holding power of cement-coated, plain and barbed nails 

 was obtained by testing a standard seven-penny nail driven to 

 a depth of one inch in dry wood and is given below. 

 Load in Pounds Per Nail. 



L<iar-!eaf Pine. Basswood. Beeck. 



Plain n 

 Barbed 



lils 



