220 



THE POPULAR EDUCATOR. 



47. USE OF THE AUXILIARY VERBS AVOIR AND ETRE. 



(1.) The verb avoir is used : 



1st. As a leading verb, to express possession, obligation, 

 duty : J'ai une maison, I have (I possess) a house ; nous avons* 

 a travailler, we have to (must) work. 



2ndly. As an auxiliary verb to form 



Its own compound tenses : j'ai eu, I have had. 



The compound tenses of the verb e'tre : j'ai et6, I have been. 



The compound tenses of the active verbs : j'ai aime, I have 

 loved. 



The compound tenses of most neuter verbs expressing an 

 action : j'ai marche", I have walked. [See exceptions to this 

 rule (3) below.] 



The compound tenses of impersonal verbs : il a plu, it has 

 rained ; il a grele", it has hailed, etc. 



(2.) The verb e'tre is used : 



1st. As a leading verb, to express existence, condition : Etre, 

 ou ne pas e'tre, To be or not to be, i.e., to exist or not to exist ; 

 elle est malade, she is ill ; ils sont,* a plaindre, they are to be 

 pitied. 



2ndly. As an auxiliary verb, to form 



All the tenses of passive verbs : Je suis aime\ I am loved. 



The compound tenses of all pronominal verbs : Je me suis 

 flatte", I have flattered myself; je me suis promene", I have 

 walked. 



The compound tenses of a few neuter verbs, though the same 

 express action : 



NOTE. Some neuter verbs which take e'tre in their com- 

 pound tenses, preserve the same auxiliary when they are used 

 impersonally : II lui est arrive un malheur, A misfortune has 

 happened to him. 



(3.) A certain number of neuter verbs, as 



rester, (o remain, to dwell 

 take sometimes avoir, and sometimes e'tre. 



1. They take avoir when we have in view the action ex- 

 pressed by the verb ; 



2. And e'tre when situation or condition is the principal idea 

 which we wish to express : 



EXAMPLES. 



With AVOIK. 

 Elle a disparu subitemcnt. 



She disappeared suddenly. 

 La fievre a cesse bier. 



The fever ceased yesterday. 



Le barometre a descendn de 

 plusieurs degrds en peu d'heures. 



Tlie barometer went down several 

 degrees in a few hours. 



II a passd en Amdrique a telle 

 epoque. 



He went to America at such a 

 time. 



Le trait a parti avec impdtuo- 

 site. L'AcADEHiE. 



The dart went off with impetu- 

 osity. 



With EIRE. 



Elle est disparue depnis quinze 

 jours. 



She has been gone a fortnight. 



La fievre est cessde , depuis 

 quelque temps. 



It is some time since the fever 

 ceased. 



II est descendu depuis une 

 heure. 



He has been down one hour. 



Les cbaleurs sont passdes. 



The heat is past. 



Les troupes sont parties de- 



puis six mois. 



L'ACADEMIE. 



The troops have been gone six 

 months. 



* Neither avoir nor etre can be immediately followed by an infini- 

 tive ; the preposition a must be placed before the latter : II est a 

 travailler, He is iorfci?ig ; j'ai a sortir, I have to go out. 



Le sang avait cessd de couler. 

 BOISTE. 

 The blood had ceased to flow. 



Ce grand bruit est cessd. 



MME. DE SiiVIGNB. 



That great noise is over (has 

 ceased). 



(4.) Rester and demeurer, meaning to stay, to dwell, to reside, 

 take the auxiliary verb avoir ; when they mean to remain, to 

 be left, they take e'tre : 



AVOIR. 



J'ai reste" plus d'un an en Italie 

 . . . MONTESQUIEU. 



I resided more than a year in 

 Italy . . . 



II a demeurd deux ans a la cam- 

 pagne. L'ACADEMIE. 



He lived (dwelt) iieo years in the 

 country. 



EIRE. 



Elle donnerait pour vous sa vie, 

 le seul bien qui lui soit restd. 

 MARMONTEL. 



She would give, for you, her life, 

 the only possession which remains 

 to her. 



Deux cents homnies sont de- 

 meurds sur le champ de bataille. 



L'ACADEMIE. 



Two hundred men remained on 

 the field of battle. 



(5.) Echapper, to escape, to pass unnoticed, to be forgotten, 

 takes the auxiliary avoir. In the sense of to say inadvertently, 

 it takes 6tre : 



AVOIR. 



Cette diffdrence ne m'a pas 

 dchappd. EOUSSEATJ. 



TTiat difference has not escaped 

 me. 



J'ai retenu le chant, les vers 

 m'ont dchappd. VOLTAIBE. 



I retained the tune, but the verses 



ETRE. 



Ce mot m'est dchappd ; pn 

 donnez ma franchise. 



VOLTAIRE. 



That word escaped my lips ; exeuse 

 my frankness. 



Excusez les fautes qui pour- 

 ront m'etre dchappdes. 



BOILEAU. 



Excuse the faults which I may 

 have committed inadvertently. 



have escaped my memory. 



(6.) Convenir, to become, to suit, takes avoir. When it is 

 used in the sense of agreeing, it takes e'tre : 



du 



Cette inaison m'a convenu. 

 Thai house suited me. 



Nous SOmmes convenus 

 prix. L'ACADBMIE. 



We agreed upon the price. 



MECHANICS. XXIII. 



COLLISION OE IMPACT. 



WE said that any force is measured by the velocity generated 

 in a second. There is one class of forces, however, which 

 cannot be so measured, because they do not act for any appre- 

 ciable length of time. These we call impulses or impulsive 

 forces ; any force which is of the nature of a blow is placed in 

 this class. 



When one body strikes against another different results will 

 ensue, according to the nature of the bodies. If an ivory ball 

 be allowed to fall on a stone slab, it rebounds or rises from its 

 surface, but the height to which it rises is less than that from 

 which it fell. Were the ball perfectly elastic, it would rise to 

 the same height. This, however, is not all that has occurred ; 

 the changes have been more complicated. On striking the slab, 

 the ball is first flattened in a slight degree. In proof of this we 

 may smear the slab with oil, and we shall find the ball marked, 

 not in a minute point as it would be if merely laid on it, but 

 over a space increasing in size with the violence of the blow. 

 The particles are thus compressed, but their own elasticity 

 causes them at once to recover their original position, and in so 

 doing the ball flies up from the slab. 



The effect, then, varies with the degree of elasticity of the 

 body. We can, however, only consider the cases of elastic and 

 inelastic bodies, not that any substances are perfectly so, but 

 by examining these we shall get at general principles, which 

 can then be applied or modified as may be required. 



We will first consider the case of inelastic bodies, and well- 

 kneaded clay or putty may be chosen as suitable substances to 

 experiment with. Wax, softened with oil, will also answer well. 



In making experiments on impact, the best plan is to procure 

 balls of the substances chosen, and, having fastened them to 

 strings, suspend them in such a way that they may just touch 

 one another. 



Let us take two such balls, c and D (Fig. 102), of equal 

 weight, and having raised them to the same height, in opposite 



