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Rh principles, and even went so far as to defend the miracles supposed to be worked at the tomb of Francois de Paris, commonly known as Deacon Paris. Unfortunately his religious opinions deprived him of his appointments and disqualified him for the rector ship, to which in 1719 he had been re-elected. It is said that the same reason prevented his election to the French Academy, though he was a member of the Academy of Inscriptions. Shortly before his death (14th December 1741) he protested publicly against the acceptance of the bull Unigenltus.

Rollin's literary work dates chiefly from the later years of his life, when he had been forbidden to teach. His once famous Ancient History (Paris, 1730-38), and the less generally read Roman History, which followed it, were avowed compilations, uncritical and somewhat inaccurate. But they instructed and interested generation after generation almost to the present day. A more original and really important work was his Traité des étuzles (Paris, 1726-31). It contains a summary of what was even then a reformed and innovating system of education, including a more frequent and extensive use of the vulgar tongue, and discarded the medieval traditions that had 1ingered in F rance. See Sainte-Beuve, Causerres du lundi, vol. vi.

ROLLINAT, MAURICE (1853-1903), French poet, was born at Chateauroux in 1853. His father represented Indre in the National Assembly of 1848, and was a friend of George Sand, whose influence is very marked in young Rollinat's first volume, Dans les brarldes (1877). The volume, however, attracted little attention, and it was with his second publication, very different in manner, that he made his reputation. In Les Névroses, with the sub-title Les flrnes, Les Luxures, Les Refuges, Les Spectres, Les Ténébres, he showed himself as a disciple of Charles Baudelaire. He constantly returns in these poems to the physical horrors of death, and is obsessed by unpleasant images. Less outre in sentiment are L'Abime (1886), La N ature, and a book of children's verse, Le Livre de la Nature (1893). He was musician as well as poet, and set many of his songs to music. He lost his reason in consequence of his wife's death from hydrophobia, and died on the 26th of October 1903.

ROLLING-MILL, a term which includes several types of machines used for producing the sectional forms (fig. 1) in which wrought iron and steel are required for the use of boiler-makers, platers and bridge-builders, and for constructional work generally. The production of wrought iron has been a diminishing industry for many years, while that of steel increases. Though the plant employed for both is alike in essential principles of design, the growth in the use of steel has revolutionized the practice, chiefly on account of the more massive dimensions in which steel sections are rolled. Iron sections are relatively small, and many are produced by piling, i.e. by building up with small portions of malleable puddled metal. There is no limit in reason to the dimensions in which steel sections can be rolled, and they are never piled, however large, but always rolled from solid cast ingots. When steel ingots are rolled into sectional forms the reduction in transverse dimensions is very great. The work begins at nearly a white heat, and continues until a low red is reached. Obviously the stresses to which the material is subjected are very severe. For this reason the process of reduction has to be effected very gradually, and especially so in those cases where reduction is being done in two directions at right angles with each other, as in channel sections (fig. 6) and joist or beam sections (figs. 7 and 8).

It might be thought, since steel is always cast previously to rolling, that it might be cast at once into the sectional forms required. But sound results could not be obtained in this way, because the gases occluded in the metal form blow-holes which are sources of weakness. The material itself, even in the solid portions, is not homogeneous. By removing the head of the ingot where the blow-holes chiefly congregate and rolling the remainder at a white or red heat, the metal is improved by consolidation, and by the work done upon it. To this practice there is no exception.

Rolling-mills are known as “two-high,” or “three-high," according as two or three rolls are mounted one over the other

. 1.—Forms of the Principal Rolled Sections. 1, 2, Flats. 3, Flat with bevelled edges. 4, 5, Flats with rounded edges. 6, Bulb bar. 7, Wedge bar. 8, Scree or grate bar. 9, Square. 10, Triangular. 11, Hexagonal. 12, Round. 13, Oval. 14, Hollow half-round. 15, Half-round. 16, Convex. 17, Square-edged convex. 18, Vee. 19, O.G. 20, Angle iron. 21, Square root, or square throat angle. 22, Round-backed angle. 23, Unequal-sided angle. 24, Acute angle. 25, Obtuse angle. 26, Bulb angle. 27, Tee. 28, Bulb tee. 29, 30, Beams or joists, or girders, or H-irons. 31, Channel. 32, Zed. 33, Cruciform section. 34, Pillar section. 35, Troughing. 36, 37, 38, Railway rail. 39, Tramway rail. 40, Heavy crane rail.

(figs. 2 and 3). In the two-high type the two rolls revolve in opposite directions, so that an ingot, slab or bloom presented to the entering side is drawn in and between the rolls, which reduce its thickness. In the case of rolls which are two perfectly plain cylinders (plate-rolls) the shape produced is that of broad, long and flat plates or sheets. Several passages (passes) are required to effect the reduction required, because this must be gradual. To regulate the amount the top roll is set down bodily by means of screws pressing on its bearings which slide in the end supports (housings). In the case of plate-rolls, which are plain cylinders, this setting down must be equal at each end. The mass of the top roll is balanced, to avoid shock when a plate is entering. The rolls are made of cast iron, and are either grain rolls or chilled rolls. The first are formed from a tough strong grade of iron, the quality which is used for all the roughing down and general work. The second are made of a highly mottled iron, cast against a cold mould (chill) of cast iron, by which a steely surface is obtained. These are used for fine finishing, or for imparting a polished surface to a section already nearly reduced to size in grain rolls. In later heavier practice, rolls of cast steel and forged steel are becoming common. They are more costly than iron, but more durable and much lighter for equal strength. They are essential in armour 'plate rolls. The length of rolls should not exceed about four times their diameter, for otherwise they are liable to spring and produce plates thicker at the centre than towards the edges. From this elementary design several types are derived. In the two-high mill it is clear that if the direction of the rotation of the rolls is always the same, then the plate being rolled must be taken back after each “pass” to the front of the rolls. Hence there is one “lost pass” for every reduction in thickness. This is the case in the “pull-over” mill, nearly obsolete. In the two-high reversing mill, introduced to avoid this “lost pass,” as soon as a plate has gone through, the direction of rotation of the rolls is reversed, and the plate is rolled again on the backward, journey, so avoiding the lost