Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/880

Rh 846 R R R S tinct sets of motions in an ordinary laying machine. Fig. 5, in which only one bobbin frame is shown, will make plain one method of communicating these three motions, which in this case are controlled by a series of three shafts, placed one within the other. The external shaft gives motion to the entire apparatus, and its revolution in one direction forms the rope, which passes away over a pulley. The second shaft controls the spur wheel a, which, geared into the spur-wheel a' attached to the bobbin frame, turns it in a direction contrary to the motion of the whole. The internal shaft gears into a spur-wheel b, which again is centred on a tubular shaft c passing into the bobbin frame, and by a pair of bevel wheels controlling the rate of motion of the " dra wing-off " pulley d, around which the strand is once wound, and from which it is conveyed by the tubu- lar shaft to a small guide pulley on the upper part of the revolving frame. An American rope-laying machine is in use, similar in principle to the form- ing machine fig. 4, from which it differs only in having the strand bobbins mounted in flyers to give the strand the necessary amount of forehard in laying. Wire Rope. Ropes made of wire have only come into use in the course of the present century, but now their employ- ment is very extensive, and they play an important part in connexion with trac- ** " tion railways, mines, collieries, hoists, steam ploughing, and many other modern developments of industry. In the year 1822 a suspen- sion bridge of wire was erected at Geneva. The wire used in this case, however, was not twisted, but consisted of parallel bundles bound with wire and other coverings wrapped spirally around them to compact and keep the whole together. A bundle of small wires so treated presents the maximum of strain-resisting power combined with great rigidity, but it is obviously unsuited for most of the uses to which rope is put. Formed wire rope, consisting of strands laid in the manner of ordinary rope, began to be made about 1837 ; and now wire ropes of many kinds and dimensions are made from char- coal iron wire of fine quality, from mild steel, and from fine crucible steel. Copper wire and brass wire are also used for rope-making. Wire ropes are stranded and laid or closed in machines which do not differ in essential features from the ordinary rope-making machinery. Both vertical and horizontal forms of revolving machines are used ; but, as the rope-closing machine has sometimes to carry as many as nine bobbins of strand, each with about two tons of wire, a vertical machine is best for enormous weights. An ingenious wire-rope machine has been invented by Mr Archibald Smith, in which the bobbins of wire are suspended, and only the framework around them and the wire drawn off are rotated for the forming and laying operations, and thus the necessity for rotat- ing these enormous weights at a high speed is obviated. The numbar of wires in a wire-rope strand are few generally from six to nine, and never more than eighteen. They are lightly twisted in the stranding machine, and they receive no foretwist in the rope-closing apparatus. The strands, on the other hand, which go to form a rope are numerous from six to nine and up- wards ; and they are always wound round a core, which is generally of hemp, but sometimes a wire core is used. A wire rope thus forms a series of gentle spirals arranged continuously round a core. A large proportion of the wire is galvanized, to protect it from rusting. The following table shows the relative circumference, weight, and strength of hemp, charcoal iron wire, and steel wire round ropes : Hemp. Charcoal Iron. Crucible Steel. Circum- ference. Weight per Fathom Circum- ference. Weight per Fathom. Circum- ference. Weight per Fathom. Breaking Strain. Working Load. Inches. Ibs. Inches. Ibs. Inches. Ibs. Tons. Cwt. 11 30 5 22 4 14 32 100 10 26 4J 16J 3i 9 24 85 9 20 3J 12 2$ 7 18 67 8 16 H 8J 8i H 16 50 7 12 y el 2* 4 11 36 6 9 2J H If 3 8 28 5 6 15 3 ij 1? 5 18 4 4 l| 2 ll 14 3 10 3 3 u If i 3 2 6 (J. PA.) RORQUAL. See WHALE. ROSA, SALVATOR (1615-1673), a renowned painter of the Neapolitan school, was born in Arenella, in the out- skirts of Naples, in 1615: the precise day is given as 20th June, and also as 21st July. His father, Vito Antonio de Rosa, a land surveyor, was bent upon making the youth a lawyer, and sent him to study in the convent of the Somaschi fathers. Here Salvator began showing a turn for art : he went in secret to his maternal uncle Paolo Greco to learn the practice of painting, but soon found that Greco had little pictorial lore to impart, so he trans- ferred himself to his own brother-in-law Francesco Fracan- zaro, a pupil of Ribera, and afterwards had some practice under Ribera himself. Above all he went to nature, fre- quenting the Neapolitan coast, and keeping his eyes open and his hand busy. At the age of seventeen he lost his father ; the widow was left unprovided for, with at least five children, and Salvator found himself immersed in a sea of troubles and perplexities, with nothing for the while to stem them except a buoyant and adventurous temperament. He obtained some instruction under the battle-painter Aniello Falcone, but chiefly painted in solitude, haunting romantic and desolate spots, beaches, mountains, caverns, verdure-clad recesses. Hence he became in process of time the initiator of romantic land- scape, with a special turn for scenes of strange or pictur- esque aspect often turbulent and rugged, at times grand, and with suggestions of the sublime. He picked up scanty doles when he could get them, and his early landscapes sold for a few pence to petty dealers. The first person to discover that Rosa's work was not as trumpery as it was cheap was the painter Lanfranco, who bought some of the paintings, and advised the youth to go to Rome. Hither in 1635, at the age of twenty, Rosa betook himself; he studied with enthusiasm, but, catching fever, he returned to Naples and Falcone, and for a while painted nothing but battle-pieces, and these without exciting any atten- tion. This class of work was succeeded by the landscape art peculiarly characteristic of him wild scenes wildly peopled with shepherds, seamen, or especially soldiers. He then revisited Rome, and was housed by Cardinal Brancaccio ; this prelate being made bishop of Viterbo, Rosa painted for the Chiesa della Morte a large and noticeable picture of the Incredulity of Thomas the first work of sacred art which we find recorded from his hand. At Viterbo he made acquaintance with a mediocre poet named Abati, and was hence incited to try his own faculty in verse. He then returned to Naples. Here the mono- polizing triumvirate Ribera, Caracciolo, and Corenzio were still powerful. Rosa was as yet too obscure to suffer from their machinations ; but, having painted a picture of Tityus Torn by the Vulture, which went to Rome and there produced a great sensation, he found it politic to follow in the footsteps of his fame, and once more, in 1638, resought the papal city. Rosa was a man of facile and versatile genius, and had by this time several strings to his bow. It is said that, still keeping painting steadily in view as his real objective, he resolved to secure attention first as a musician, poet, improvisatore, and actor his mother-wit and broad Neapolitan dialect (which appears to have stuck to him through life) standing him powerfully in stead. In the carnival he masqued as Formica and Capitan Coviello, and bustled about Rome distributing satirical prescriptions for diseases of the body and more particularly of the mind. As Formica he inveighed against the farcical comedies acted in the Trastevere under the direction of the celebrated Bernini. Some of the actors, in one of their performances, retaliated by insulting Rosa, but the public was with him, and he now enjoyed every form of