ROL 



ROL 



many pieces of Des Cartes, conceived 

 such an affection for Renault, on account 

 of his attachment to this philosopher, 

 that he gave him his daughter in mar- 

 riage against all the remonstrances of his 

 family. 



Ro'hault's Physics were written in 

 French, but have been translated into 

 Latin by Dr. Samuel Clarke, with notes, 

 in which the Cartesian errors are correct- 

 ed upon the Newtonian system. The 

 fourth and best edition of Renault's Phy- 

 sics, by Clarke, is that of 1718, in 8vo. 

 He wrote also " Elemens des Mathema- 

 tiqucs," " Traite des Mechanique," and 

 "Entretienssur la Philosophic." But these 

 dialogues are founded and carried on 

 upon the principles of the Cartesian phi- 

 losophy, which has now little other merit 

 than tiiat of having corrected the errors 

 of the ancients. Rohault died in 1675, 

 and left hehind him the character of an 

 amiable, as well as a learned and philo- 

 sophic man. 



His posthumous works were collected 

 and printed in two neat little volumes, 

 first at Paris, and then at the Hague, in 

 1690. The contents of them are, 1. The 

 first six books of Euclid. 2. Trigonome- 

 try. 3. Practical Geometry. 4. Fortifi- 

 cation. 5. Mechanics. 6. Perspective. 

 7. Spherical Trigonometry. 8. Arith- 

 metic. 



ROLANDRA, in botany, so named in 

 honour of Daniel Rolander, a pupil of 

 Linnaeus, who travelled to Surinam ; a ge- 

 nus of the Syngenesia Polygamia Segre- 

 gata class and order. Natural order of 

 Composite Capitate. Cinarocephalae, Jus- 

 sieu. Essential character : florets bun- 

 dled into a head with scales interposed ; 

 calyx partial, two-valved, one-flowered ; 

 corollets hermaphrodite ; down none. 

 There is but one species, viz. R. argen- 

 tea, a native of the West Indies. 



ROLLING mill, in mechanics, a ma- 

 chine for working metals into plates, or 

 bars, which are required of an even thick- 

 ness. In the Plate Rolling-Mill, are three 

 elevations of a machine for this purpose, 

 A B, D E, in all these figures is a massive 

 frame of cast iron, consisting of two dis- 

 tinct cheeks, A B and D E, which are 

 connected together by being both affixed 

 to an iron plate, F F, bolted down upon 

 two ground sills, G G, supported on ma- 

 sonry, and forming the foundation for the 

 whole machine ; each cheek has an oblong 

 mortice, a b, through it; a strong iron 

 screw, d, is screwed through the upper 

 end of each cheek, and has a wheel on 

 the top of it, with teeth, to receive a 



handspike to turn it by. I K are the two 



rollers made of cast iron, and very truly 

 turned in a lathe; they have pivots, it, 

 k m, at each end, turned at the same 

 time, and with the greatest accuracy; 

 these pivots are supported on bearings of 

 brass in the cheeks; those of the lower 

 rolle;-, K, fit in the bottom of the mor- 

 tices, it b, (fig. 1 and 3) through the 

 cheeks ; the upper ones, e e, are movea- 

 ble, sliding up and down in the mortices 

 by the action of the screw, d. The weight 

 of the upper roller, when nothing is be- 

 tween the rollers, is sustained by an iron 

 strap, 11, at each end, embracing the pi- 

 vots, and going through the brass bear- 

 ing, ee. Its ends are tapped, and have 

 nuts screwed upon them to prevent their 

 return through the ends of the collar, p, 

 which fits in a groove cut round the 

 screw, d, so that it cannot come off'; the 

 collar is made in two halves, which are 

 held together by the ends of the strap, n, 

 going through both at the place where 

 they overlap each other ; by this means 

 the upper bearings are firmly connected 

 with the screws, to rise and fall with 

 them ; and at the same time, the pivots 

 of the upper roller are held tip to their 

 bearings by the straps, H, going under 

 them. The end of the pivots of the rol- 

 lers are formed into squares beyond the 

 bearings, and the pivots of one end of 

 each roller have two cog wheels, L M, 

 fitted on them ; they are bhov/n iaccways, 

 (in fig. 1) and are lioth alike ; they cause 

 the two rollers to move with an equal ve- 

 locity ; the other square, A', on the lo\ver 

 roller, is fitted into a box, M, by which it 

 is joined to a strong shaft, O, which com- 

 municates a rotatory motion to the rol- 

 lers. This shaft receives its power from 

 a water-wheel, steam engine, horses, or 

 other first moving power : s is a small 

 trough made of iron plate, punched full 

 of holes, it is supplied with water by a 

 pipe, n, and constantly drops a small 

 quantity of water upon the rollers, and 

 thus keeps them cool when they are roll- 

 ing hot work : -w is a bar of iron fixed be- 

 tween the two cheeks by wedges, the 

 upper side is on a level with the top of 

 the lower roller ; a small distance above 

 this is another iron bar, x, parallel to the 

 former ; between these the article in- 

 tended to be rolled is introduced to the 

 rollers. 



Rolling mills are chiefly used for draw- 

 ing out iron bars after they have been 

 manufactured into bar iron by the forge 

 hammer; the rollers leave a smoother 

 surface, and make a bar of more even 



