34 Forestry Quarterly. 



which the moist air forming in the drying-kiln is constantly- 

 drawn out. Once more should the importance of the removal 

 of the moist air be emphasized here ; it must be drawn backward 

 toward the entrance-door in order to prevent the cones which are 

 getting more and more dry from becoming heated again with 

 moisture present. 



The exit-door of this drying-kiln consists of panes of glass .12 

 to .15 of an inch (3 to 4 mm) thick, properly framed; the kiln- 

 master can, therefore, see whether the cones have opened prop- 

 erly. According to the time of year, the quality of the cones, etc., 

 the opening of the cones occurs in periods of time of different 

 length which practice and observation soon learn to recognize. 



The order of operation is as follows : 



The kiln-master opens the exit sliding door, draws out the truck 

 nearest to him, at the same time pulling forward the others 

 nearest the door, goes to the entrance door, opens it and shoves 

 in a truck filled with fresh-drying-trays, which he couples to the 

 next truck in order to close the entrance-door again. 



The operation is a continuous one, going forward day and 

 night so long as there are cones. 



It is uneconomical, even harmful, to cool off the drying-rooms 

 oftener than is necessary to clean the stove grates, draughts, flues, 

 etc. Competent stove-factories design stoves requiring the least 

 possible interruption in heating for continuous efficiency. 



It is not at all difficult for present day science to control 

 the hot air accurately and to maintain it constantly at a tempera- 

 ture of 104° to 122° F. (40° to 50° C.) with occasional attention 

 to a reliable little regulating apparatus. One need only think of 

 the central heating system employed in modern liouses every- 

 where. 



In order to guard against all contingencies thermographs and 

 hygrographs, visible from the outside, are constructed in the 

 drying-kilns (also as a check upon the kiln-workman). 



The design of the drying-kiln, the introduction of warm air 

 ^maintained uniformly at 113° to 122° F. (45° to 50° C), its 

 regular distribution in the drying-kiln and the removal of the 

 damp air as it cools, is not at all new to the technique concerned 

 with such things ; similar operations are carried on in many 

 kinds of industries ; I call to mind, for instance, the drying ar- 

 rangements in modernly-equipped pasteboard factories. The 



