dough-making, while the slower motion was intended to draw out and
thoroughly aerate the dough. To discharge the dough, the trough was
tilted by means of a worm and worm wheel, the latter being secured to
the trough. Several variations of this type of kneader are still in
use. The machine known as the "Universal" kneader consists of a trough
set horizontally, within which rotate on horizontal axes a pair of
blades lying in the same plane. These blades are curved and are geared
together by means of differential spur wheels, with the object of
running the two spindles at unequal speeds. The bottom of the trough
is divided into two semi-cylindrical cavities, separated by a ridge.
Each blade plunges into its own cavity, and the action of these arms
tends, while pressing the dough against the sides and base of the
trough, to bring it quickly back towards the centre. The differential
speed has the advantage of effecting a more thorough mixing of the
dough, as it brings together pieces of dough which have not yet been
mingled, the blades pushing the dough from one cavity to the other. To
hasten the kneading process it is desirable occasionally to reverse
the motion by a turn of a hand wheel on the same shaft as the two
pulleys. This wheel governs all the motions of the blades. The trough,
which is set low, is tilted over, when the dough is ready, by an
endless chain operated by a hand winch. The effort required for this
operation is very slight, as the trough is balanced by two weights.
The action of tilting does not interfere with the blades, which
continue rotating until stopped by the hand wheel. The Universal
kneader was designed to imitate as closely as possible the action of a
pair of skilled human arms and hands, but of course works at a much
greater speed.

Another form of dough mixer which is extensively used consists simply
of a drum made of sheet steel supported by two A-shaped standards at a
sufficient height from the floor to allow a trough to be run
underneath to receive the dough when ready for the moulding board. In
this drum are two tight-fitting doors. The interior is fitted with no
blades or knives, but presents a free cylindrical space, with the sole
exception that, set not very far from the circumference, there are
several fixed rods passing from one side of the drum to the other.
These act as mixers of the dough. The door is opened and t