The three negatives are each printed on sensitized copper, as was noted with the black and white halftone; they are then turned over to the re-etcher, who may be rightly termed an “artist-etcher.” He has before him three prints on copper; on each of them are tones which to his trained eye are too light or too dark to produce the desired result when printed with the other two, which also vary more or less. It is his duty to strengthen and reduce and otherwise manipulate the plates so that they will, when finally printed, have the desired result. For every particular use to which an engraving can be put, there is some particular style or grade of engraving better adapted than any other. The successful use of halftones, whether in black and white or in colors, depends on the care with which the particular screen is selected to suit the paper stock and printing conditions. To illustrate this, the 150-line screen has 22,500 stipples to the square inch. It is apparent, therefore, that only certain kinds of paper can be used for such halftones, whereas a 60-line screen contains only 3,600 stipples to the square inch, which permits its use on a newspaper stock. The production of engravings is just as highly technical and scientific and involves as much experience and judgment in their application as any of the learned professions. * * * * * Where are Milk-Pails Filled from Trees? In South America there are some trees known as “cow-trees” which, when wounded, yield a rich, milky, nutritious juice in such abundance as to render it an important article of food. This fluid resembles in appearance and quality the milk of the cow. The cow-tree is a member of the bread-fruit family, and is most common in Venezuela, growing to the height of a hundred feet. The leaves are leathery, about a foot long and three or four inches broad. In British Guiana the name is given to another large, much-branched tree, and there are also other varieties in Para and along the Rio Negro, which is a tributary of the Amazon River. How did the Wearing of a Crown Originate? When we speak of a crown now we mean the head-dress worn by royal personages as a badge of sovereignty, but it was formerly used to include the wreaths or garlands worn by the ancients upon special occasions. Among the Greeks and Romans, crowns made of grass, flowers, twigs of laurel, oak, olive and so forth, and later of gold, were made use of as honors in athletic contests, as rewards for military valor, and at feasts, funerals and so forth. It is, however, with the eastern diadem rather than with the classic corona that the crown, as a symbol of royalty, is connected; indeed, it was only introduced as such a symbol by Alexander the Great, who followed the Persian usage. Antony wore a crown in Egypt, and the Roman emperors also wore crowns of various forms, from the plain golden fillet to the radiated or rayed crown. [Illustration: CROWNS