Page:Encyclopædia Britannica, Ninth Edition, v. 1.djvu/790

Rh 74(&amp;gt; A M N A M Fio. brought by Mr Hale to the form shown in Fig. 5. Con- greve rockets were kept point first by sticks screwed into their bases, which acted on the principle of the feathers of an arrow. The Halo rocket is kept point first by rotation, caused by the gas escaping from the vents pressing against the curved shields. The second class of rockets arc signal rockets, made of paper, and containing stars, which throw a bright light in falling. The third class are the rockets used to cany a line and establish communication between a wrecked vessel and the sea-shore. (c. o. u.) AMNESTY (d/AVTjcrria, oblivion), an act of grace by which the supreme power in a state restores those who may have been guilty of any offence against it to the position of innocent persons. It includes more than pardon, inasmuch as it obliterates all legal remembrance of the offence. It is chiefly exercised towards associations of political criminals, and is sometimes granted absolutely, though more frequently there are certain specified excep tions. Thus in the case of the earliest recorded amnesty, that of Thrasybulus at Athens, the thirty tyrants and a few others were expressly excluded from its operation ; and the amnesty proclaimed on the restoration of Charles II. did not extend to those who had taken part in the execu tion of his father. Other celebrated amnesties are that proclaimed by Napoleon on 13th March 1815, from which thirteen eminent persons, including Talleyrand, were cxceptcd ; the Prussian amnesty of 10th August 1840; and the general amnesty proclaimed by the Emperor Francis Joseph of Austria in 1857. The last Act of amnesty passed in Great Britain is 20 Qeo. II., c. 52, which proclaimed a pardon to those who had taken part in the second Jacobite rebellion. AMOL, or AAIUL, a town of Persia, in the province of Mazandcran, about 12 miles above the mouth of the Hera/, a river which flows into the Caspian Sea. It is not walled, and is now a place of no great importance, but in and around it there are mins and ancient buildings which bear witness to its former greatness. Of these the most conspicuous is the magnificent mausoleum of Seyed Quam-u-deen, king of Sari and Amol, who died in 1378. At Amol there is a bridge of twelve arches over the Ileraz, and the bazaars of the town are large and well supplied. The population is aboixt 40,000, but a great number of these leave the city in summer to tend their flocks. AMONTONS, GUILLAUMK, a celebrated French ex perimental philosopher, was the son of an advocate who had left his native province of Normandy and established himself at Paris, where the subject of this notice was born on the 31st August 1GG3. The exertions of genius fre quently take a particular direction from accidental circum stances. A severe illness with which Amontons was afflicted in his early youth had the effect of rendering him almost entirely deaf, and consequently of secluding him in a great measure from the ordinary intercourse of society. I .ring compelled by this accident to depend for his enjoy ments on the resoxirces of his own mind, he began to take great pleasure in the construction of machines of various kinds, and in the study of the laws of mechanics, a path of inquiry which he pursued through life with unremitting ardour and distinguished success. One of the first objects which engaged his attention was the discovery of the perpetual motion, an attempt which, though necessarily unsuccessful, was productive of greater advantage to him than it has usually been to those who have pursued that vain chimera. Amontons devoted himself particularly to the improvement of instruments employed in physical experiments, a subject which requires the finest applica tions of mechanical principles, and which till that time Lad not met with a due share of attention. In 1687, before he had attained his 24th year, he presented to the Academy of Sciences an hygrometer of his own invention, which was received with approbation by that learned body. In 1G95 he published the only work which he has given to the world. It was dedicated to the Academy, and entitled Remarqites ct Experiences Physiques sur la Construction d un NoiivelClepsydre, sur les flaromctres, les Thcrmomctrcs, ct les Hygromktres. After Huyghens s beautiful application of the pendulum to the regulation of the motion of clocks, any attempt to revive the clepsydra, an incommodious instrument, and not susceptible of much accuracy, might seem to subject its author to the imputation of not suf ficiently appreciating the great importance of a discoveiy which has so completely changed the face of astronomical science ; but the object of Amontons was to produce an instrument capable of measuring time on board ship, in circumstances where the motion of the vessel rendered such timekeepers as were then known useless. The machine which he constructed is said to have been extremely ingenious, and probably differed entirely from those of the ancients, among whom the clepsydra was in common use. In 1G89 Amontons was admitted into the Academy of Sciences, the Memoirs of which he enriched with many important contributions. The first paper which ho presented after his admission was one on the theory of friction,, a subject then involved in great obscurity, and on which his inquiries tended to throw con siderable light. After that appeared in succession de scriptions of a new thermometer, and of numerous experi ments made with the barometer relative to the nature and properties of air, a detailed account of all which is given in the history of the Academy. In the course of these investigations he found that the boiling point of water varies with the pressure of the atmosphere, a discovery made almost contemporaneously in England by I)r Hal ley. 15y his countrymen he is generally regarded as the inventor of the telegraph ; and he had the honour of exhibiting the methods by which he proposed to accomplish the object in view before some members of the royal family. It appears, however, from a paper read by Dr Hooke to the Royal Society in 1684, that that ingenious philosopher had brought the telegraph, in theory at least, to a state of far greater maturity than Amontons, and nearly 20 years earlier. The experiments of the latter were made about the year 1702. It may be regarded as a curious fact in the history of inventions, that although the great import ance of telegraphic communication is obvious, and the method of accomplishing it was clearly explained by Hooke, and its practicability demonstrated by Amontons, it con tinued to be regarded as of no practical value, and was not regularly applied to useful purposes till nearly a century afterwards, at the time of the French Revolution. Amontons died in 1705, aged 42. AMOOR, AMOUR, or AAIUK, a large and important river of eastern Asia, formed by the confluence of the Argun and the Shilka, at a place called Ust Strelkoi, in 53 19 N. lat. and 121 50 E. long. Both these rivers come from the south-west: the Argun, or Kerulen as it is called above Lake Kulon, through which it flows about half-way between its source and Ust Strelkoi, rises near Mount Kentei, in 49 N. lat. and 109 E. long. ; the Shilka is formed by the union of the Onon and the Ingoda, both of which rise in the Kingan mountains, not far from the source of the Argun. The Amoor proper flows at first in a south-easterly direction for about 800 miles, as far as 47 42 lat. ; it then turns to the north-east, and after a total course of over 1GOO miles discharges itself into the Sea of Okhotsk, opposite to the island of Saghalicn. Its principal tribu-