141 



ROCKET. 



ROMAN ARCHITECTURE. 



112 



ant in the construction of the Urge military rocket, and will be found 

 fully treated in Captain Boxer's ' Treatise on Gunnery,' p. 67, chapter 

 on Rockets. 



The rod serves to guide the rocket in its flight : for the common 

 centre of gravity of the rocket and rod being a little below the top of 

 the latter (in the one-pound rocket it is 2 feet from the upper ex- 

 tremity of the rocket, or 7 feet from the lower extremity of the rod) ; 

 if we suppose the rocket to be fired vertically upwards, and a vibration 

 should take place about the centre of gravity by any excess of pressure 

 on one side arising from an irregularity in the burning of the com- 

 position, the resistance of the air against the long portion of the rod 

 below that centre, like a force acting on the longer arm of a lever, will 

 exceed the force by which the vibration U produced, since the latter 

 force acts on the rocket and the upper part of the rod which constitutes 

 the shorter arm of the lever ; and thus the vibration is checked or 

 prevented, and the rocket is enabled to ascend steadily. But, in pro- 

 portion as the composition burns out, the common centre of gravity 

 approaches nearer the middle of the whole length of the rocket and 

 rod ; and the resistance of the air acting at length nearly equally 

 above and below that centre, it can no longer counteract any inequality 

 in the burning of the composition. Thus, in falling, the top of the 

 rocket, or the rocket end of the rod, is downward*. 



The rod performs a similar service when the rocket is impelled 

 ntolly or obliquely ; for, while the force of projection is great 

 enough to carry the rocket forward, and the centre of gravity of the 

 whole is near the rocket end of the rod, the resistance of the air 

 against the tail of the latter will nearly prevent any vibration ; but, 

 when the centre of gravity has got near the middle of the length, the 

 head of the rocket begins to droop, and at length the whole comes 

 obliquely to the ground. It has ha|>pened however, from the rod 

 being too short or too light, that the weight of the rocket, when the 

 latter had been projected with small elevation, has so much in- 

 curvated the line of its path before the composition has burnt out, 

 that the rod has turned over it, and the whole has been driven t the 

 ground in a direction tending towards the place from whence it was 

 projected. In signal rockets, the stick is fixed to the side of the 

 cylinder, a very defective arrangement, as shown by Captain Boxer 

 in his chapter on Rockets. 



Rockets whose diameters vary from 1 to 2 inches have been found 

 to ascend vertically to the height of about 500 yards ; and those whose 

 diameters vary from 2 to 3 inches, have ascended to the height of 

 1200 yards. The distances at which rockets can be seen vary from 

 35 to 40 miles ; and the times of ascent from 7 to 10 seconds. (Robins's 

 ' Tracts," vol. ii.) 



Rockets, to be employed as military projectiles, were invented by 

 Sir William Congreve, and, in the British artillery service, a body of 

 men, called the rocket troop, was organised expressly for their manage- 

 ment. Sir William caused the rockets to be made with strong iron cases 

 of cylindrical forms, and terminating at the head with a paraboloi.l ..r 

 cone ; and he attached the rod so that its axis should coincide in 

 direction with that of the rocket Five classes of rockets were first 

 made, namely, 3, 8, 12, 24, and 32 pounders. The 32 pounders have now 

 however been abolished. 



The paraboloid head is hollow, and can be used as a shell by filling 

 it with powder, or as a shot by leaving it empty. The 12 and 24 

 pounders can also be used as carcasses by substituting a conical 

 carcass head with four vents for the paraboloid head. The shell is 

 fitted with a fuze fixed in the base, that is, nearest the rocket com- 

 position. It also has a small hole at the apex, through which the 

 bursting charge is introduced. Through this hole the boring bit is 

 introduced when it is necessary to bore out any fuze composition f r 

 short ranges. When the ranges are very short, it is necessary to bore 

 out some of the rocket composition also. But this is a dangerous 

 operation and hardly repays the trouble. The stick is screwed into 

 the bottom of the ease, an iron disk , and round it are five vent* for 

 the escape of the gas. In order that the direction of their flight may 

 be more certain, military rockets are, in general, fired from tubes 

 fixed hi stands in such a manner as to be adjustable to any elevation, 

 and raised sufficiently above the ground to keep the stick off it ; and 

 the proper elevation, at least for the smaller nickels, is about one 

 degree for each hundred yards in the required range. From their 

 form they penetrate to a considerable depth when fired against timber 

 or earth : 12 pounder rockets, after a range of 1260 yards, have been 

 found to enter the ground obliquely as far as 22 feet. The principal 

 inconvenience attending rocket practice is the powerful action of 

 the wind when it blows in a direction perpendicular, and even oblique, 

 to the intendt.il line of flight The effect is very peculiar, for the wind 

 acting on the tail, a long lever, drives the head up into the wind. The 

 rocket should therefore be laid to leeward. 



Rockets, being much lighter than any other kind of ordnance, and 

 capable of being used with <>r without carriages, are well adapted for 

 conveyance in mmurtalnoui countries. When fired in volleys against 

 troops, their effect is likely to create much disorder ; and those which 

 act as carcasses, when fired again >, building*, will almost certainly 

 cause their destruction. Besides being employed in the siege of 

 Copenhagen, rockets were used at the bonibnnlnient of Flushing 

 (1809); and in 1813 the British rocket-troop rendered considerable 

 service at the battle of Leipzig. The advance of a French column 



against an inferior force of British troops was checked by a well 

 directed fire of rockets at the passage of the Adour in the last- 

 mentioned year; and it is said that the explosion of the powder- 

 magazine which in 1840 produced such disastrous effects at Acre, was 

 caused by the fall of a rocket on the building. Rockets were used both 

 by the French and English before Sebastopool. A rocket was invented 

 ; by Mr. Hale a few years ago to be used without a stick ; the rocket was 

 something similar to the Congreve rocket, but at the base, which is iu 

 form like the frustum of a cone, besides a large vent hole in the axis 

 there were five smaller holes cut obliquely through the exterior 

 surface of the conical part. These holea, termed " tangential holes," 

 are made with the object of giving a rotatory movement to the rocket 

 to keep it point foremost. [RlFLE.] The rocket was restrained by a 

 spring in the tube till it had obtained sufficient initial velocity to 

 prevent ita drooping. 



ROD. [Pencil.] 



ROGATION DAYS. It was a general custom formerly, says 

 Bourne, and it is still observed in many country parishes, to go round 

 the bounds and limits of the parish ou one of the three days preceding 

 Holy Thursday ; when the minister, accompanied by his church- 

 wardens and parishioners, used to deprecate the vengeance of God, beg 

 a blessing on the fruits of the earth, and preserve the rights and 

 properties of the parish. The primitive custom used by Christians ou 

 this occasion was, for the people to accompany the bishop or some of 

 the clergy into the fields, where Litanies where made, and the mercy of 

 God implored, that he would avert the evils of plague and pestilence, 

 that he would send them good and seasonable weather, and give them 

 in due season the fruits of the earth. The Litanies or Rogations then 

 used gave the name of Rogation Week to this time. They occur as 

 early as A.D. 560, when they were first observed by Mamertius, bishop 

 of Vienna, on account of the frequent earthquakes that happened, and 

 the incursions of wild beasts, which laid in ruins and depopulated the 

 city. (Walifred, Stral, c. 28, ' De Repub. Ecclesiast.') In the caucus 

 of Cuthbert, archbishop of Canterbury, made at Cloveshoo, in the year 

 747, it was ordered tlfct Litanies, that is Rogations, should be observed 

 by the clergy and people, with great reverence, on the seventh of the 

 calends of May, according to the rites of the church of Rome, which 

 terms this the Greater Litany, and also, according to the custom of 

 our forefathers, on the three days before the Ascension of our Lord, 

 with fastings, Ac. (Wilkins, ' Concil. Brit.;' Spelm., v. ' Litania.') 

 In the Book of Common Prayer they are still retained. The three Ro- 

 gation Days are the Monday, Tuesday, and Wednesday before Holy 

 Thursday, which are appointed fast days. The previous Sunday is 

 Rogation Sunday. 



Rogation Week, in the northern parts of England, is called Gang 

 Week, from to gang, which in the north signifies to go. Gang-week, 

 occurs in the rubric to John, c. 17, in the Saxon Gospels; and 

 Gang-dagas are noticed in the laws both of Alfred and Athelstan. 



(Brand's Popular Anlii/. ; Brady's data Calmdaria.) 



ROOL'F. AND VAGABOND. [VAGBAOT.] 



KOLLIXH, ROLLERS. [IRON MANUFACTURE.] 



ROLLING STOCK. [RAILWAY.] 



ROLLS. [RECORDS.] 



ROLLS-COURT, the Court of the Master of the Rolls, is usually held 

 in the Knllx HniMing* in Chancery Lane; which were originally a 

 boose or hospital for the reception of Jewish converts. When the 

 Jews were banished from England by King Edward I., there was h'ttlo 

 use for an hospital of this kind ; whereupon it was assigned to the 

 Master of the Rolls, who had thenceforth the denomination of Maputo- 

 Rahtlonm, Kemrdontm, &c., rt Vattoi Domua Com-ertorum. One or two 

 convert* were maintained on a poor pittance in this house in the 16th 

 century. 



ROLLS, MASTER OF THE, an officer of the Court of Chancery, 

 second only to the chancellor himself. Originally he had, as the name 

 implies, the custody of the rolls or recorded proceeding!) of that court, 

 and, it seems also, of any other documentary matter belonging to that 

 court. But the custody had long been merely nominal, and the actual 

 care of them was vested in certain keepers, under the authority of 

 an act of Parliament (1 & 2 Viet. c. 94), by which, however, very 

 extensive powers are given to the Master of the Rolls with respect to 

 the custody and use of them. This act further commits to him 

 the records also of the Common-Law Courts and of the Court of 

 Exchequer. 



By what means the Master of the Rolls became divested of the 

 peculiar duties indicated by the name, is a point of legal antiquarianism 

 which has not been satisfactorily elucidated; nor is it quite clear 

 when or how he came to sit to hear causes in equity. The chief 

 duties of this officer now are judicial ; but from his decrees there is 

 an appeal to the chancellor, or lords justices. 



l!< 'MAN AM M. [Au-ll.] 



ROMAN ARCHITECTURE. Although, M was ikl under ABCHI- 

 TFCTURE, the Romans derived their architecture, a they did most 

 of their arts, immediately from the Greeks, yet they undoubtedly 

 borrowed the circular arch, and the fondness for circularity in the 

 plans of their buildings, from the Etruscans ; and these features were 

 what mainly brought about the modifications of style and ornamenta- 

 tion, the variety of form and the constructive peculiarities, which dis- 

 tinguish Roman architecture. We cannot here trace the progress of 



