Page:Encyclopædia Britannica, Ninth Edition, v. 3.djvu/273

Fig. 5 represents a kneading-macliine, of a highly approved form, used in the great Scipion bakery of Paris, the inven- tion of M. Boland. Externally it is like the former, and it is also geared to move at two rates of rapidity. It has further an adjustment by which the force of the motion is increased while its rate is diminished. The main pecu liarity of M. Boland s joeirin m&chanique consists in the form of the revolving blades inside the trough. These blades are so arranged that they operate when in motion some- what like alternate screws, and so toss backward and for ward the dough when it is thin, and lift and draw it out when stiff, passing it to each side of the trough alternately. An entirely different form of kneader is seen in fig. 6. This also is of French origin, the invention of M. Deliry-Desboves of Soissons (Aisne). Its construction and operation are thus described : " The trough is a cast- iron basin, which turns on a vertical axis. The interior is provided with a kneader, shaped like a lyre, which first works up the dough and then divides it during the entire periodfrof operation. Two other implements are also used, of a helical form, to draw out and inflate the dough in all directions, part by part, as is practised in kneading by hand. . . . The baker in charge can regulate the paste without stopping the mechanism. The water and leaven are first introduced, the trough is then set to work, the workers employed to manipulate the dough are put in gear, and the leaven being diluted and flour added, the kneaders are also put in gear. After the lapse of twelve or fifteen minutes the dough is sufficiently kneaded, and, by turning the hand wheel fixed to the screw on the vertical shaft, the three kneaders are thrown out of gear. The implement which effects the cleaning of the trough is then removed, and its place supplied by a balance-hook, by which the dough may be weighed in the trough itself. It is simply necessary to turn the basin on its axis as re quired, until the whole of the dough is weighed." (Villam,

Etudes sur ^Exposition de 1867.)

FiQ. 5. Boland s Kneading- Machine.

Fia. G. Kneading-Machine of Deliry-Desboves.

The fourth form of mechanical kneader we shall describe is that invented by Messrs Vicars of Liverpool, who are extensive makers of all forms of machinery connected with bread and biscuit making. This machine (fig. 7) consists of two vertical shafts, carrying radial arms. These arms pass each other in opposite directions, so that, in addition to a tearing action on the dough, which the knives have on passing each other, they have a screw action, pressing the dough down on one side and up on the other. The vessels containing the dough are made of wood, of an oval form, to correspond with the action of the machine. One considerable advantage connected with Messrs Vicars s machine is, that any number of troughs can be worked by the same pair of mixing shafts, as the troughs are mov able, and are raised to, or lowered from, the blades of the mixer by means of friction wheels and spur gear. A baker can thus have several troughs containing sponges in different stages of advancement, all mixed by one pair of shafts, and all in their turn being made into dough by the same shafts.

FIG. 7. Patent Vertical Mixer.

Much thought and skill have been expended in the

endeavour to effect improvements in the ordinary form of a baker s oven, but hitherto no plan has been devised which produces bread of a quality superior to that fired in the oven which is commonly used. A baker s oven of the common description is a low vaulted chamber, about 10 feet long, by 8 feet wide, and 30 inches high. It is built and floored of stone or brick, and has a small door in front by which the moulded dough is put in and the loaves withdrawn. At one side of this door, in the extreme corner, are placed the furnace and fire-grate, opening into the oven, and at the opposite corner, the smoke flue by which smoke escapes from the interior. The heat is by this arrangement carried throughout the entire oven, and when the temperature is sufficient the fire is withdrawn, the flue shut, and the dough is quickly introduced on a " peel," or long wooden shovel. Various efforts have been made to effect the heating of ovens by fire external to the chamber itself, but they fail to produce that radiation of heat which is found essential to good baking. Perkin s hot-water oven for some time met with favour in Great

Britain, and a modification of it was employed in France.