ARTIFICIAL DRYING OF WHEAT. 159 



blowing air through it." This principle of forcing air 

 through masses of material to be preserved or dried is un- 

 doubtedly a very valuable one, and deserves the attention 

 of all agriculturists. The means by which its advantages 

 can be obtained are so simple and inexpensive, that they 

 cannot, or should not, stand in the way of realizing these 

 advantages. We have no doubt whatever, from what we 

 know of the astonishing power of currents of air, that it 

 would pay, in every sense of the word, to provide a central 

 opening to all stacks of every crop, and to force into not 

 through these tubes a large quantity of air by means of 

 a hand fan, or, still better, to work the fan by steam, and 

 force the air through pipes leading through a steam chest 

 or the upper part of a boiler, thus obtaining warmth and 

 dry air. The outside of the pipes being surrounded with 

 steam, the air forced through them in its way from the 

 fanners to the stack would be soon raised to a sufficiently 

 high temperature. But even where the plan of forcing air 

 into the central opening in the stacks was not adopted, 

 considerable advantage would still be gained from the open- 

 ing or central tube alone. All that would be necessary in 

 this case would be to have it, if solid, well perforated with 

 apertures, and a free opening at top and bottom. To get 

 the latter, the stack would require to be raised from the 

 ground ; this, however, is done in all cases of improved 

 stack construction. 



24. As evidence of the extraordinary desiccating or dry- 

 ing powers of currents of heated air passed through, or 

 in contact with, various materials, we may here give some 

 interesting results, for which we are indebted to Mr. 

 Davison of London, who has devoted more time than any 

 man living to this branch of engineering. The principle 

 on which Mr. Davison's apparatus is conducted is simply 

 forcing large bodies of air through a series of arched pipes 

 heated by an ordinary furnace, and passing thus, at a high 

 temperature, into the chamber containing the materials to 

 be dried. The air is forced through the pipes by means of 

 a fan. The process has been applied to the drying of al- 



