122 Forest Club Annual 



with the result that the runaway crashes into the cars ahead. 

 This usually means either a car through the kiln door or a truck 

 off track. In either case half a dozen men are required to right 

 the accident 



Each chamber holds 16 cars, but it is customary to remove 

 only half of the cars at a time. The reason for this is that there 

 is a limited space for storage below the kiln. 



After being dried, the lumber is unloaded below the kiln 

 mainly by means of a mechanical unloader operated by a small 

 engine. This works just opposite from the stacker, raising tier 

 after tier up onto a table where it is marked for the different 

 purposes by the marker. As the material moves along the table 

 on the three endless chains, it is taken off by the chain gang and 

 placed on separate trucks. 



The temperature of the kilns, which should be quite con- 

 stant, varies greatly. The automatic recording thermometer 

 showed at times a daily variation of 80 F. As a rule the average 

 temperature is about 200 F. This great change in temperature 

 is due largely to the poor system of firing the boilers from which 

 the steam is secured. 



Practically all the merchantable western species are kiln- 

 dried in greater or lesser amounts. Since much material is needed 

 for boxes, Sitka spruce (Picea sitchensis) heads the list, with 

 the other species in regular order Douglas fir (Pseudotsuya ta.ri- 

 folia Britt.), western hemlock (Tsuga heterophylla), western red 

 cedar (Thuya plicata) and cottonwood (Populus frcuiontii). 

 There is much doubt as to the correctness of the species name 

 "fremontii" for the cottonwood. This tree is not used to a very 

 great extent ; only an occasional log reaches the mill and simply 

 those boards that are clear and free from knots enter the kiln. 



Material of various sizes is run through the kiln. Of clear 

 spruce there is 3x4 and 4x4 inch stock and inch boards from 4 

 to 24 inches wide ; boxwood, spruce and hemlock are usually 

 I 1 /-* inches thick and from 6 to 12 inches wide. Boxwood in- 

 cludes all the common stocks of spruce and hemlock which will 

 not pass for clear. Clear hemlock inch boards average from 4 to 

 (S inches in width. Only clear fir and a limited amount of clear 

 cedar inch boards from 4 to 8 inches wide are kiln-dried, unless 

 a special order of thicker stock is required. The thicker stock 

 is not stacked by means of the mechanical stacker but by hand. 



Upon inspecting the material that has passed through the kiln 

 a number of defects are usually observed. The principal one, 

 especially in Douglas fir, is that of warping. As the lumber 

 dries it shrinks and the tiers become loosened, consequently 



