Drying-machines. There are several kinds of these in use. For the drying of long webs of calico and other fabrics, a machine, consisting of a series of metal cylinders revolving in an iron frame, and heated internally with steam, is employed. Sometimes the rollers are arranged in vertical, sometimes in horizontal lines, and the cloth passes over them in a continuous web.
Centrifugal drying-machines or hydro-extractors consist of a circular wire-basket mounted on a shaft and set in a close metal jacket. The fabrics or stuffs to be dried are placed in the basket, which revolves at a speed varying from 700 to 2000 revolutions per minute. The water flies off by the centrifugal action, and escapes from the inclosing cylinder by a discharge pipe. This form of drying-machine, which has several modifications, is very largely used and for a great variety of purposes.
A recent method of drying wool and other textile material is by the Blackman air-propeller. The wool is spread over a perforated surface which is in connection with a revolving propeller, with peculiarly shaped blades, placed at the top of a vertical trunk or shaft. This apparatus dries the wool by drawing heated air through it and expelling the air at the top through a turret in the roof of the building in which it is placed.
Yarns are frequently dried by passing them slowly through a hot chamber, by means of continuous chains, upon which rollers carrying the hanks are placed.
The drying-apparatus in connection with a paper-making machine consists of a series of drums with wooden spars on their circumference. These are mounted horizontally on an iron frame, and move at a slow speed as the web of paper passes over them. There are fanners within the drums which drive heated air against the inner surface of the paper.