The _screening machine_ consists of a roller-shaped sieve, so divided, that the corn which is placed at one end passes over a large surface of wire as the sieve revolves, and this operation removes from it external impurities, such as sand and dirt. When it arrives at the end of the screw the wheat falls into a hopper, by which it is conveyed by spouts into small hoppers, placed over one side of each pair of millstones. From these hoppers there are spouts placed in nearly a horizontal line, which spouts conduct the corn from the hoppers to the eye of the millstone. They are attached to the hopper, so as to admit of a horizontal motion, which is effected by a projecting part of the axle or spindle of the stone, called a _damsel_. It is shaped like a cross, so that, by the revolution of the millstone, it keeps tapping the end of the spout, and gives a rapid vibratory motion to it, which causes a regular supply of corn to enter the eye of the stone; by the action of the stones the corn is reduced to flour, which passes, by means of spouts, into the troughs on the ground floor. [Illustration: Scales and Weights. Troughs.] The _troughs_ in which the flour is kept; the _scoop_ and _scales_ for weighing small quantities; the _claw_ for moving and the _steelyard_ for weighing sacks, are the other principal objects seen in a mill. _Jacob’s ladder_ is the name given to a revolving band fitted with a number of leathern cups. These revolve with the band through the flour and serve to carry it up a shaft from one floor to another. [Illustration: Steelyard.] THE BAKER. [Illustration: BAKING OVEN AND KNEADING TROUGH.] Of all the trades that are carried on in large towns there is none more important than that of the Baker. In some parts of the country, where people make their own bread at home, or at all events have all the materials for making it, and know how to mix the different ingredients, it is of less consequence; but only imagine what would be our dismay in London, if we got up some morning and heard that all the bakers had agreed not to send in the rolls for breakfast, and that we must be satisfied to live upon puddings and vegetables until they set to work again to make bread. And yet, in the early part of their history, several nations of which we read at school had no knowledge of the trade of a Baker. Until they discovered the art of making proper bread, and somebody showed them the use of an oven, the Romans made their meal into a sort of porridge, or knew no better than to mix it into flat cakes, which they cooked on hot stones or in the wood ashes of their fires. The Anglo-Saxons were a little better off, for they mixed leaven with their dough, to make the cakes lighter and better; but you will remember—by the story of King Alfred, who when he was in disguise and going to watch the Danish camp, was left in the neatherd’s hut to watch the cooking of the cakes—that they were baked in the embers of burnt wood upon the hearth.