RUD 



following table : in which the firft column exhibits the 

 angle of incidence ; the fecond, the impulfions really ob- 

 ferved ; the third, the impulfes, if they had followed the 

 duplicate ratio of tin- lines ; and the fourth, the impulfes 

 according to the limple ratio of the fines. 



The error in the fecond principle of the theory is ftill 

 greater, and the action on one part of the fail or hull is lo 

 greatly modified by its action on another adjoining part, that 

 a ftay-lail is often feen hanging like a loofe rag, although 

 there is nothing between it and the wind ; and this merely 

 becaufe a great fail in its neighbourhood lends oil a lateral 

 ftream of wind, which completely hinders the wind from 

 getting at it. Till the theory of the action of fluids be 

 cltablifhed, therefore, we cannot tell what are the forces 

 which are acting on every point of the fail and hull : 

 therefore we cannot tell either the mean intenfity or direction 

 of the whole force which acts on any particular fail, nor the 

 intenfity and mean direction of the refiftance to the hull ; cir- 

 cumftancea absolutely neccilary for enabling us to fay what 

 will be their energy in producing a rotation round an/ par- 

 ticular axis. In like manner, we cannot, by fuch a compu- 

 tation, find the fpontaneous axis of converfion (fee Rota- 

 tion), or the velocity of fuch converfion. In Ihort, we 

 cannot pronounce with tolerable confidence a priori what will 

 be the motions in any cafe, or what dilpofitiuns of the fails 

 will produce the movement we wifh to perform. The ex- 

 perienced feaman learns by habit the general effects of every 

 difpofition of the fails ; and though his knowledge is far 

 from being accurate, it feldom leads him into any very 

 blundering operation. Perhaps he feldom makes the belt 

 adjullment poffible, but feldomer (till docs I very 



far from it ; and in the molt general and important problems, 

 fuch as working to windward, the refult of much cxperit 

 and many corrections has fel '.I ed .1 trim of the lails, which 

 is certainly not far from truth, but (it mull be acknow- 

 ledged) deviate;; widely and uniformly from the I 

 the mathematician's clofet. The honed tar, t foi , mull 

 be indulged in his joke on the ulelcfs labours of the mathe- 

 matician, who can neither hand, reef, 1 



Bouguer 1 la Manoeuvre des Vailleaux. Falco- 



ner' Diet, art. Helm; and Euler's Complete Theory 



of the Construction and Properties of Veil I , translated by 

 Mr. Watfon, 1776, hook ii. chap. vii. viii. ix. 



A narrow rudder 19 bell tor a (hip's failing, provided (he 

 can feel it, thai is, be guided and turned by it ; for a broad 

 rudder will hold much water when the helm is put over lo 



R U D 



any fide ; but if a (hip have a fat quarter, fo that the water 

 cannot come quick and ilrong to her rudder, (he will require 

 a broad rudder. 



The aftmotl part of the rudder i: called the rake of the 

 rudder. 



Large canal boats have dafp-ruddtrs, about half their 

 length being moveable on hinges, fo as to fold and fhorten 

 them before the entering of a lock. 



RuDDER-f oa/x, are coverings made of well-tarred canvas, 

 to prevent the water from running in at the rudder-hole. 



Rudder-/>o«j, in a Ship, are the cheeks of that iron 

 of which the pintle is part, which is fattened and nailed 

 down about the rake of the rudder. 

 Rudder- Pendants. See Pendants. 

 RvnDER-Rope. Sec Rope. 

 RuDDER-7'ari/e. See Tackle. 



RUDDIMAN, Thomas, in Biography, was born in 

 the parifh of Boyndie, Banffshire, 111 the year 1674, where 

 he received the firft rudiments of his education, and in 1 690 

 he was fent to King's college, Aberdeen, where he obtained 

 a burfary. He took the degree of M. A. in 1694, and in 

 the following year he was elected matter of the public fchool 

 of Laurence-Kifh. In 1700 he removed to Edinburgh, and 

 two years afterwards he was appointed librarian to the 

 faculty of advocates. In 1 709 he publifhed Johnfon's me- 

 trical paraphrate of Solomon's Song, and foon after he added 

 a very accurate gloffary to the folio edition of Gawin 

 Douglas's tranflalion of the Eneid. His fituation at the 

 advocates' library was fo favourable to his literary purfuits, 

 that he declined an invitation from the magiitrates of Dun- 

 dee, to the office of rector of the grammar-fchool in that 

 town. In 1714 he publifhed his " Rudiments of the Latin 

 Tongue," which became a very popular book in Scotland, 

 and was ufed in many fchools in South Britain. In 1725 he 

 edited " Buchanani Opera omnia," in two vols, folio, to 

 which he added notes critical and explanatory. About the 

 fame time he commenced the bufinefs of printer, in con- 

 junction with his brother Walter. In 1720 he publifhed the 

 firft part of his " Grammatics Latinse Inftitutiones," which 

 was very foon followed by Ins " Grammatical Exercifes." 

 Of the various works which lflued from the prefs of the 

 Ruddimans, the molt important were the " Greek Tefta- 

 ment," and an edition of the works of Livy : the latt is 

 reckoned an extremely correct edition. He alto edited An- 

 derfon's " Diplomats el Nmtiifmata Scotiae," to which he 

 prefixed a learned preface. He exhibited great critical acu- 

 men in his vindication of " Buchanan's Verfion of the 

 Pfalms," againfl the objections of Mr. Mann, and by 

 " Critical Obfervations on Burrman's Commentary on 

 1, nt an's Pharfalia." Some treatiles on difputed points 

 of Scottifh hiftory involved him in controvcrlies, in which 

 he met with much abufe, but he did not lofe his own 

 temper, though he was a warm advocate for the national 

 independence of Scotland, and much attached to the h.iufe 

 of Stuart. At an advanced age his eye-fight began to 

 fail him, and he refigned the office of librarian to tht 1. culty 

 of advocates in 1752. He died in January 1757, at th 

 of s^. Chalmer's Life of Ruddii; 



RUDDOCK, in Ornithology, an 1 for the 



rubecula, more commonly known by the name of the red- 

 bnaji, or robin-red-hreajl. 



R.UDELSHOI EN, in Geography, a town of Germany, 

 in the margraviate of Anfpach ; four mil 1.. t>t Uffen- 

 heim. 



R.UDELSTADT, a town of ipality 



of Schweidnitz ; 16 miles W. of Schweidnitz. N. Lit. 50* 



42'. E. long. 1 5 59'. 



RUDEN, 



