Page:Popular Science Monthly Volume 45.djvu/393

Rh other directions and the subject of drying lumber slept for some years.

A patent was granted to Hannah and Osgood, November 27, 1866, 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 operation 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 dealers, must be interested in the subject. To air-dry hard-wood lumber by simple, natural means involves the loss of interest on immense 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 unscientific and hence unskillful drying by artificial means often involves 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 subjected to the same treatment. The only theory acted upon was that the lumber, being green or wet, must be dried in the shortest possible time. To effect this result it was only thought necessary 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 temperature 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