741 



ATTWOOD'S MACHINE. 



AUBAINE. 



742 



weights were six pounds, the machine would not move : therefore, the 

 moving pressure is the one pound by which the one weight exceeds the 

 other. This weight, if it had only its own mass to move, or if it fell 

 freely, would generate 32J feet of velocity per second ; but before this 

 system can move, 6 + 7 or 13 pounds must be stirred by 1 pound, and 

 there will only be the 13th part of 321 feet of velocity produced in one 

 second that is, about 2f feet. Therefore, in one second, the heavier 

 weight will fall only 1^ foot ; and in 5 seconds, 25 times as much, or 

 30 feet. And the velocity acquired may be reduced in any proportion, 

 by making the weights more nearly equal. 



Attwood's machine is a pulley, the pivots of which, instead of being 

 placed in a block, are sustained on FRICTION WHEELS (which see), to 

 diminish the friction. Two weights are hung over this by a string, and 

 the mass moved consists of the two weights, the pulley, and the 

 friction wheels. But it is proved in mechanics that the effect, both of 

 having the mass of the wheels to move, and of the friction, is a constant 

 retarding force : for instance, in the preceding illustration, the machine 

 might be so constructed that the effect should be to make the system 

 move as if the larger weight were 64 pounds instead of 7, and the 

 pulley were without density and friction. The velocity can be so far 

 reduced as to render the resistance of the air insensible. 



The length described in any time is measured by a vertical scale of 

 feet, placed close to the line of motion of one of the weights. There is 

 also a pendulum beating seconds in an audible manner. To measure 

 the velocity acquired at any point, the moving pressure (the excess of 



one weight above the other) must be taken off, in order that there may 

 be no fresh accession of velocity, or that the system may proceed only 

 with the velocity acquired. This is effected by making the larger 

 weight in two parts, one part equal to the smaller weight, and the 

 other of course to the excess or moving pressure. The latter is so 

 formed that it cannot pass through a certain ring, while the former 

 can. By fixing this ring to any required point of the scale of feet, the 

 moving pressure is taken off when the larger weight passes through it. 



Smaller weigbt. 



Larger da 



Attwood'i machine is not a very satisfactory proof of the laws of 

 uniformly accelerated motion, because the constancy of the retardation 

 caused by the complicated motion given to the pulleys, and by the 



friction, is a more difficult experimental fact than the one to be proved. 

 Of the four principles, 1, the law of uniformly accelerated motion ; 

 2, the constancy of the retardation caused by the having to communi- 

 cate every acceleration also to the pulley and friction wheels ; 3, the 

 constancy of the retardation arising from friction ; 4, the smallness of 

 the resistance of the air to small velocities, this machine may be 

 made to prove any one to a spectator who admits the other three. 



In Attwood's machine, a body falling freely is not observed, but one 

 in which the descent is diminished in a known proportion. In an 

 apparatus constructed by Morin, the actual 

 descent of the falling body is exhibited and 

 analysed in an ingenious manner. This ap- 

 paratus consists of a cylinder moving on a ver- j--jro:Ja/ U' 

 tical axis at a uniform rate by means of clock- 

 work. Parallel with the axis of the cylinder 

 are two wires, which serve as guides to a small 

 cylindrical weight, which carries a pencil with 

 its point pressing gently against the surface of 

 the cylinder. There is a contrivance for detach- 

 ing the weight, and also for letting it fall. Now 

 it is evident that if the cylinder were at rest, 

 the pencil in descending would simply trace a 

 vertical line on its surface, while if the cylinder 

 revolve and the pencil be at rest, it would 

 trace a horizontal circle round it. If, however, 

 while the cylinder is revolving on its axis at a 

 uniform rate, the weight carrying the pencil be 

 allowed to fall, the pencil will trace a curved 

 line round the surface of the cylinder, and if 

 the surface of the cylinder be divided into 

 equal parts by the vertical parallel lines rr, ss, 

 1 1, &c., the intervals between the moments at 

 which these parallels pass under the pencil will 

 be equal, since the motion of the cylinder is 

 uniform. Hence the vertical space through 

 which the weight falls in the first interval will 

 be ' n, in the first two intervals p' p, in the first three intervals 

 q' q, and so on. 



AUBAINE, the name of the prerogative by which the sovereigns of 

 France formerly claimed the property of a stranger who died within 

 their kingdom, not having been naturalised. It also extended to the 

 property of a foreigner who had been naturalised, if he died without a 

 will, and had not left an heir ; as likewise to the succession to any 

 remaining property of a person who had been invested with the privi- 

 leges of a native subject, but who had quitted, and established himself 

 in a foreign country. (See Merlin, 'Repertoire de Jurisprudence," 

 torn. i. p. 523.) It is called in the French laws, the ' Droit d'Aubaine.' 

 Authors have varied in giving its etymology. Nicot (' Thresor de la 

 Langue Francoyse tant ancienne que moderue,' fol., Paris, 1606) says it 

 was anciently spelt Hobaine, from the verb kober, which signifies to 

 remove from one place to another ; Cujacius (' Opera,' fol., Neap. 1758, 

 torn. ix. col. 1719) derives the word from advena, a foreigner or 

 stranger; and Du Cange (' Glossar.,' v. Aubain) from Albanus, the 

 name formerly given to the Scotch, who were great travellers. Manage 

 ('Diet. Etym.,' fol., Paris, 1694) says, some have derived the word 

 from the Latin, alibi natus, a person born elsewhere, which seems the 

 best explanation. (See also Walafridus Strabo, ' De Vita S. Galli,' 1. ii 

 c. 47.) 



This practice of confiscating the effects of strangers upon their death 

 was very ancient, and is mentioned, though obscurely, in one of ibe 

 laws of Charlemagne, A.D. 813. (' Capitularia Regum Francoruir, 

 curante P. de Chiniac, fol., Paris, 1780, coL 507, 6.) 



The Droit d'Aubaine was originally a seignorial right in the province> 

 of France. Brussel, in his ' Nouvel Examen de 1'Usage general des 

 Fiefs en France pendant le xi., le xii., le xiii., et le xiv. siecle,' 4to, 

 Paris, 1727, torn. ii. p. 944, has an express chapter, ' Des Aubains,' in 

 which he shows that the barons of France, more particularly in the 

 12th century, exercised this right upon their lands. He especially 

 instances Raoul, Comte de Vermandois, 1151. 



Subsequently however it was annexed to the crown only, inasmuch 

 as the king alone could give the exemption from it, by granting letters 

 of naturalisation. 



Various edicts, declarations, and letters patent relating to the Droit 

 d'Aubaine, between the years 1301 and 1702, are referred to in the 

 ' Dictionnaire Universel de Justice ' of M. Chasles, 2 torn, fol., Paris, 

 1725 ; others, to the latest time, are given or referred to in the ' Code 

 Diplomatique des Aubains,' par J. B. Gaschon, 8vo, Paris, 1818. The 

 Due de Levis, in his speech in the Chamber of Peers, when proposing 

 its final abolition, 14th April, 1818, mentioned St. Louis as the first 

 monarch of France who had relaxed the severity of the law (compare 

 ' Etablissemens de S. Louis,' 1. i. c. 3) ; and Louis le Hutin as having 

 abolished it entirely in 1315 (compare the ' Recueil des Ordonnances du 

 Louvre,' torn. i. p. 610), but, as it turned out, for his own reign only. 

 Exemption from the operation of the Droit d'Aubaiue- was granted in 

 1364 by Charles ,V. in favour of persons born within the states of the 

 Roman Church. Louis XI., in 1472, granted a similar exemption to 

 strangers dwelling at Toulouse ; and Francis I., in 1543, to strangers 

 resident in Dauphine". Charles IX., in 1669, allowed exemption from 



