HARDWOOD RECORD 



27 



East Face of Pile 



air travels remains tlic same. 



Moisture Controls Speed of Air 



Where gravity alone is employed to move the air, its speed or 

 velocity of movement will depend upon the gradually increasing 

 weight of this air as it takes on moisture. Its travel will be in a 

 downward direction, following least resistance, and its speed will 

 depend upon the amount of moisture absorbed liy a unit of volume 

 in a unit of time. 



By using the term "drying jiower " it is intended to employ a 

 more convenient and more easily understood expression than ' ' mois- 

 ture deiicit. ' ' Drying power changes with the temperature of the 

 air and represents that amount of moisture which a given amount 

 of air may still absorb on top of that moisture which it already 

 contains before it shall reach 100 percent saturation, jirovided that 

 its temperature remains constant. 



Drying power, therefore, is the result of the .-lir temperature and 

 of the water vajjor contained in the air, and since the temperature 

 of the air decreases and its moisture content increases as the air 

 passes through a pile of lumber, consequently tlie drying power of 

 the air gradually decreases from point of its entry into the pile to 

 point of its exit. 



In open air, or yard drying, the drying power of the air changes 

 during the day with the position of the sun, which controls the 

 temperature of the entering air, with the changing humidity of 

 the air, and with the vaiying wind pressure and direction. 



In the warmer seasons of the year this drying power may become 

 so pronounced as to produce casehardening by too great an absorp- 

 tion of moisture from the lumber, and possibly damage, if the mois- 

 ture content of the lumber happens to be near the critical point, and 

 therefore the drying power of the air must be otfset by limiting the 

 volume which may pass over the lumber in a unit of time. 



{To bl- conthiiiril ill \in'rmhrr '^~ith isKiii) 



High Humidity 

 Dry Kiln 



CIRCULATION IS KING 



Of the three controUing factors 

 in Dry Kihi operation — heat, 

 humidity, and circulation— cir- 

 culation is king-. The circula- 

 tion is your transportation sys- 

 tem delivering the necessary 

 heat and humidity to your lum- 

 ber. If your circulation falls 

 down, or is inadequate and not 

 uniform your drying suffers 

 accordingly. 



The largest manufacturers of 

 drying equipment now offer 

 you their services in regard to 

 your lumber drying problems. 



"The Kiln with the Circulation 

 You Can Understand" 



for 



LUMBER — PANELS — VENEERS 

 COOPERAGE — LAST BLOCKS 



Largest Factory in the World Devoted to the Manufacture of Air 

 Moving Equipment 



B. F. STURTEVANT COMPANY 



HYDE PARK, BOSTON, MASSACHUSETTS 



Atlanta, Ga. ; Cincinnati, Ohio; Chicago, 111.; New 



York, N. Y.; Philadelphia, Pa.; Rochester, N. Y.; Seattle, 



Wash.; San Francisco, Calif. 



