The smaller mills were turned by slaves, the larger by draft animals. Men pushed on the projecting shafts, but animals wore a collar which was attached by a chain or rope to the end of the crosspiece at the top. The links of the chain running to the crossbeam are distinctly shown in a relief in the Vatican Museum (Fig. 222), in which a horse is represented turning a mill. Blinders are over the eyes of the horse, which seems also to be checked up in order to prevent eating. A square hopper rests on the crossbeam, and the miller is bringing a measure of wheat to pour into it. On a shelf in the corner of the room is a lamp. [Illustration: Fig. 223.--Section of bake oven.] The ovens were not unlike those still in use in many parts of Europe. They were shaped like a low beehive, generally with some kind of a flue in front to make the fire burn inside while they were being heated. The oven in the bakery described above, however, has a special device for saving as much heat as possible (Fig. 223); it is entirely enclosed in a smoke chamber (_b_), with two openings above (_d_) for the draft. Fires were kindled in such ovens with wood or charcoal; the latter was probably used here. When the proper temperature for baking had been reached, the ashes were raked out (in Fig. 223, _e_ is an ashpit), the loaves of bread shoved in, and the mouth closed to retain the heat. A receptacle for water stands in front of our oven (_f_), a convenience for moistening the surface of the loaves while baking. The front of the oven (at _c_) was connected with the rooms on either side, as may be more clearly seen by referring to Fig. 219. In the kneading room (18), where were found remains of a large table and shelves, the loaves were made ready, and could be passed through one opening to the front of the oven; the hot loaves could be conveniently passed through the other opening into the storeroom (19). [Illustration: Fig. 224.--Kneading machine, plan and section.] In many establishments a machine was used for kneading; the best example is in a bakery on the north side of Insula xiv in Region VI. Such kneading machines are seen also in ancient representations of the baker's trade, as in the reliefs of the tomb of Eurysaces, near the Porta Maggiore at Rome.