One of the best methods of artificial seasoning is that known as the Desiccating Process, introduced by Davison, which consists in exposing the timber to a current of air in a kind of oven. The air is impelled by a fan with a velocity of 100 feet per second; the fan, air-passages, and oven, or chamber, being so proportioned that a quantity of air equal to one-third of the volume of the space is blown through it per minute. An opening in the roof allows the moisture to pass away. Samples of the wood are weighed from time to time until it is found that the required proportion of weight has been lost.

* ' Transport des Bois,' p. 225.

† ' Repertory of Patent Inventions,' vol. vi., p. 228.

The best temperature for the hot air varies with the kind and dimensions of timber. Thus for

The time for drying varies with the thickness; thus -

These periods are fixed on the supposition that the process is carried on during twelve hours per day only instead of twenty-four.*

Another method for which a patent was taken out by M. Guibert is said to give better and more certain results than those obtained from the use of dry and hot air.

It consists of filling the drying oven with smoke produced by the distillation of such matters as sawdust, waste tan, smiths' coal, etc. By means of a ventilator, ingeniously arranged, a rotatory movement round the logs laid to season is given to the smoke, so as to obtain an average uniform temperature in every part. By this plan, as the distillation of the combustibles is always attended with a considerable discharge of steam, all cracks and splits appear to be prevented.†

* ' Civil Engineer Journal,' vol. xii., p. 310. ‡ De Lapparent's ' Essay on the Prevention of Decay in Timber.'