TEN 



r i-: N 



,.ti..n. hj Sir James Mackiuto-h. of his character as 

 diplomat)-! and .-late-man. 'lie was a mu-t admirable 

 pcisou. lie seems to be the model of a negotiator, unit- 

 ing politeness and address to honesty. Hi- men: 

 donit i.in is also very great: in an age c 



ticnii attached In liberty, and . from 



endangering the public quiet. 1'eihaps diplomatic habits 

 had smoothed away hi- turbulence too much 

 government a.- England.' M ifkiiit'i^h. ii. I'.'ii. 



Dr. John.-on, speaking of Sir William Temple as a writer, 

 has said that -lie was the first writer who save, cadence to 

 Kiiglish prose.' 



There arc two or three biographies of Temple; one by 

 AIM 1 Hover, published about fourteen years after his death, 

 and anoiher by his si.-ter. J.ady (iiffard, prefixed to the 

 edition of his works published in 1731, 2 vols. follp. A 

 very laboured and somewhat diffuse life has been lately 

 published by the late Mr. Peregrine Court enay, and to this 

 work all who wish for the fullest information a.s to Tem- 

 ple's life will resort. The best edition of Temple's works 

 la that published in IS14, in 4 vols. Svo. 



TENACITY (.from the Latin ' tcnacitas,' 'Die power of 

 holding'), a property of material bodies by which their 

 parts resist an efloit to force them asunder. 



This property is a result of the corpuscular forces actini; 

 within the insensible spaces supposed to exist, between the 

 particles of bodies : it is consequently different in different 

 materials, and in the same material it varies with the 

 of the body with respect to temperature and other 

 circum>tai: 



Those corpuscular forces consist of attractions which 

 vary according to unknown laws with the distances of the 

 particles from one another, and even at certain distances 

 they become repulsions: but, in all bodies except the 

 elastic fluids, the combined actions of all the particles 

 produce that coherence which constitutes the tenacity of 

 the massscs. In those fluids the particles have no co- 

 herence, and when the pressures to which they are subject 

 are removed, those particles immediately separate from 

 each other with forces depending, probably, upon the 

 quantity of caloric with which they arc combined. In 

 non-elastic fluids and in solids, tenacity exist-, but in very 

 different degree*; its force depending upon differences 

 in the intensity of the attracting powers between the par- 

 ticles, upon differences in the distances of the particles 

 themselves, upon the action of the calorie, and, in some 

 ca.sc.-, upon variations in the pressure of the atmosphere. 



The molecules of liquids adhere tp one another, and 

 generally to those of solid bodies, by attractive forces 

 which decrease very rapidly ; and, at insensible distances 

 from the supposed places of contact, the adhesion entirely 

 disappears [CAPILLARY ATTRACTION] : the real tenacity of 

 the molecules being, as Dr. Young observes, equal to the 

 s of their mutual attractions above the forces of re- 

 pulsion arising from the actions of tho calorific particles. 

 It is on account of the small distance to which the attrac- 

 tions of the fluid molecules extend, an'd to the freedom 

 with which the particles move on one another, that fluids 

 apjiear to have so little tenacity; but from the weight of 

 water whi.'h it supports in glass tubes, Dr. Kobison has 

 estimated that the mutual attiactions of the particles of 

 water on a suifacc equal tu one square inch must far ex- 

 1 190 pounds. 



1 du.-t. or sand, while dry, have no power of 

 adhering together, probably because their fomis d< 

 permit a sufficient number of points on their surfaces to be 

 brought within the dHanec at which corpuscular attrac- 

 tions take place; but, if .-lightly wetted, the mutual atliae- 

 tions between the ditat and the liquid produce a certain 



,iy : this i- Me in clay moi-lciud 



with water: for being then drawn into the form of a mil, 

 it i> capable of bearing a small wcL- led fiom it. 



Tenacity exists ill various de:: -id tluids, as oil. 



gnm dissolved in water, ^c. : sealing-wax and ;'!a-- 

 when . ir biittlcnc.-s, ami aic capab.e ( ,i be- 



ing moulded into any form, while their pailn 

 considerable degree of adhesive pov 



if solids constitute'-, in part, the subj 

 the power of bodiet to resist strains ; and in IM.S, 



OK, will be found a table p. s. col. -' of the 

 its which would overcome the Ion ion in 



enbly lix. nd and pulled in the direc- 

 tion of their length : those weights may be considered as 



the measures of tenacity in the different kind.- of material ; 

 and it may be here added that, from a mean of se\ end ex- 

 periments made b) Mr. Tel ford on the tenacity of I 



the breaking -Ircnuth, when reduced to that which 

 it would be if tli. i - section of the liars 



had been one square inch, is l?.i| tons. The 



cylinders or parafielopipeds varying in length from i 



"> inches to 12 foet 3 inches: and in area of section, from 

 <>-.">(> to :} 14 square inches ; they stretched in length Horn 

 '1 inches to 4 inches before they broke. Mr. Tel ford found 

 also that a bar of ca-t -steel bore suspended from it 'J7'!'2 

 ton-, a bar of bli-tcrcd steel 17''^7 tons, and of cast-iron 

 Welsh, pi;; 7 -d ton-; the area of the section in all be- 

 ing one square inch. Tenacity in solid bodies varies greatly 

 with their temperature. M. Coulomb took a piece of cop- 

 per-wire, which, when cool, carried i 11. suspended from 

 it : and, upon brinirin<: it toa white heat.it would 'scarcely 

 bear lUlbs. 



Though, when a piece of metal is fractured, the parts 

 will not by simple adjunction adhere together; yet. in 

 some cases, by hammering them upon one auotlier, so 

 many points on their surfaces may be bnniirht within the 

 limits to which the force of colic-ion extends, that they 

 will acquire a tenacity equal to that which the metal hud 

 in its natural state. 



The tenacity of wood is much greater in the direction of 

 the length of its fibres than in the transverse direction, 

 the fibres bciuir united by a substance having little cohe- 

 sive power. Few experiments have been made oil the 

 tenacity of wood perpendicularly to its grain, as it is 

 called : and from those of Mr. Kincrson it appears to vary 

 from one-tenth to one-seventh of the tenacity in the other 

 direction. When a strain takes place in the direction of 

 the fibres, they become disengaged from one another, 

 and thus lose the strength which arises from their lateral 

 cohesion: they then become subject to separate strains ; 

 the weaker ones are first ruptured, and at length all give 

 way, leaving an irregular surface of fracture. 



With respect to metals, the proce-scs of forging and 

 wire-drawing increase their tenacity in the longitudinal 

 direction ; the augmentation of friction and lateral 

 sion, arising from the particles bciuir forced together in the 

 transverse direction, more than compensates for the dimi- 

 nution of the attraction which may result from the parti- 

 cle- being forced or drawn farther asunder longitudinally. 

 Copper and iron have their tenacity more than doubled, 

 while gold, silver, brass, and lead have it more than tripled 

 by those metals being drawn into wire. 



Mixed metals have, in general, greater tenacity than 

 those which are simple: the tenacity varies with the dif- 

 ferent proportions in which the metals are mixed ; and 

 the proportions which produce the greatest strength are 

 different in different metals. The only experiments on 

 this subject with which we arc acquainted arc tin 

 Muschcnbrock ; and from these we find that a compound 



. i- . . i : i. -. _.. ii_ i i i , 



of which 'f were gold and J copper had a tenacity, or force 

 of cohesion, more than double that of the gold' or copper 

 alone : brass, composed of copper and zinc, had a tcnacif v 



more than double that of the copper, and nearly twenty 

 time- as urcat as that of the /"me : a metal of which J wei'e 

 block-tin and ] lead, had a strength more than double 

 that of the tin ; and a mixture of which j were lead and J 

 zinc had a tenacity nearly double that of the zinc, and 



five time i- that of the lead alone. 



TK.XAII.I.K, in Fortification, is a rampart raised in the 

 main ditch, immediately in front of the curtain be' 



ind, in it- most simple form, it 



tw. i lares coinciding in direction with the face- of the 

 -d. consequently, forming with each other a re- 

 entering auirlc. Generally, however, it consist- of three 

 face-, of which two have the direction- just mentioned 

 and the thud form.- a curtain which is paiallcl to that of 

 the enceinte. See I', /'/-. 1, li \si ION, and f in the plan, 

 1)._.'I77 . Ki'iuim STION. 



work was originally proposed I I, in order 



. ethe jiurpi.se, in part, of a tans- e-bra\ c [ KM 



niii-ketiy on it- faces uiay be 



employed, in conjunction with tliose of ailillery and 

 tn ON the flanks of the bastion 

 if the enemy acro-s the main ditch when alien 

 mount a breach in the ramparts of the place. 



The relief of the lenaillc, or the elevation ol 

 above the bottom of the ditch, is determined iv 



