KILN-DRYING HARD WOOD. 377 



other directions and the subject of drying lumber slept for 

 some years. 



A patent was granted to Hannah and Osgood, November 27, 

 186G, for " an improvement in the method of drying lumber/' and 

 other patents followed in rapid succession, a full history of which 

 is shown by the records of the Patent Office. But it does not 

 appear that any really successful kiln was built until the year 

 1875, when one was erected at Stillwater, Minn., and a little later 

 one in Chicago, if the records are correct, for Pond and Soper, 

 though Turner Brothers had one built about the same time. The 

 dates as to when the first steam drier was put in successful opera- 

 tion are a little foggy, claims being made both for Stillwater, 

 Minn., and St. Albans, Vt. 



The question of the artificial drying of hard- wood lumber has 

 assumed such importance that all, both manufacturers and deal- 

 ers, must be interested in the subject. To air-dry hard-wood lum- 

 ber by simple, natural means involves the loss of interest on im- 

 mense sums of money invested in the lumber while it is awaiting 

 the slow and not always satisfactory or sure process of Nature ; 

 while, on the other hand, it is a well-admitted fact that unscien- 

 tific and hence unskillful drying by artificial means often in- 

 volves a loss greater than the other. 



The earliest attempts at the artificial drying of lumber made 

 no difference in the matter of varieties of wood or quality of stock. 

 All kinds and qualities were run in promiscuously, and all sub- 

 jected to the same treatment. The only theory acted upon was 

 that the lumber, being green or wet, must be dried in the short- 

 est possible time. To effect this result it was only thought neces- 

 sary to create as great a heat as possible within the limits of safety, 

 and to raise it to the maximum degree in the very shortest time, 

 the limit being often raised to a reckless height, not infrequently 

 reaching the point of actual partial carbonization to an extent 

 that killed the life of the lumber so treated. Often the kiln would 

 be hastily opened for the removal of dry stock, while it was under 

 full headway, with the heat up to the highest point, and green and 

 often frozen lumber hurried in to receive at the very outset a 

 blast of heat as near the point of combustion as it was possible to 

 raise it with any degree of safety. 



This, of course, has reference more particularly to the days 

 of dry hot air and furnace heat, though the same was true of 

 the earliest attempts at steam heating. Nothing was known or 

 thought of the effect of thus subjecting lumber to a high temper- 

 ature at the very first stage of the drying process, and nothing 

 was known of the effect of high temperature upon different 

 varieties of wood or the same variety under different conditions, 

 whether entirely green, or partially or wholly air-dried. One 



