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 public vaccinator was now required to visit the homes of children for the purpose of offering vaccination with glycerinated calf lymph, “or such other lymph as may be issued by the Local Government Board.” The operative procedure in public vaccinations Was formerly based on the necessity of carrying on a weekly series of transferences of vaccine lymph from arm to arm; and for the purposes of such arm-to-arm vaccination the provision of stations, to which children were brought first for the performance of the operation, and again, after a week’s interval, for inspection of the results, was an essential. The occasional hardships to the mothers, and a somewhat remote possibility of danger to the children, involved in being taken long journeys to a vaccination station in bad weather, or arising from the collecting together in one room of a number of children and adults, one or more of whom might happen to be suffering at the time from some infectious disorder, are a few of the reasons which appeared to render a change in this regulation desirable; as a matter of fact, it would appear that nothing but good has arisen from the substitution of domiciliary for stational vaccination. There have naturally been some curious discussions before the magistrates as to what is “ conscientious” or not, but the working of the so-called “ conscience clause ” by no means justified the somewhat gloomy forebodings expressed, both in Parliament and elsewhere, at the time of its incorporation in the act of 1898. On the contrary, its operation appeared to tend to the more harmonious working' of the Vaccination Acts, by affording a legal method of relief to such parents and guardians as were prepared to affirm that they had a conscientious belief that the performance of the operation might, in any particular instance, be prejudicial to the health of the child.

VACHEROT, ÉTIENNE (1800-1897), French philosophical writer, was born of peasant parentage at Torcenay, near Langres, on the 29th of July 1809. He was educated at the École Normale, and returned thither as director of studies in 1838, after some years spent in provincial schoolmasterships. In 1839 he succeeded his master Cousin as professor of philosophy at the Sorbonne. His Histoire critique de l'école d'Alexandrie (3 vols. 1846-51), his first and best-known work, drew on him attacks from the Clerical party which led to his suspension in 1851. Shortly afterwards he refused to swear allegiance to the new imperial government, and was dismissed the service. His work Démocratie (1859) led to a political prosecution and imprisonment. In 1868 he was elected to the French Academy. On the fall of the Empire he took an active part in politics, was maire of a district of Paris during the siege, and in 1871 was in the National Assembly, voting as a Moderate Liberal. In 1873 he drew nearer the Conservatives, after which he was never again successful as a parliamentary candidate, though he maintained his principles vigorously in the press. He died on the 28th of July 1897. Vacherot was a man of high character and adhered strictly to his principles, which were generally opposed to those of the party in power. His chief philosophical importance consists in the fact that he was a leader in the attempt to revivify French philosophy by the new thought of Germany, to which he had been introduced by Cousin, but of which he never had more than a second-hand knowledge. Metaphysics he held to be based on psychology. He maintains the unity and freedom of the soul, and the absolute obligation of the moral law. In religion, which was his main interest, he was much influenced by Hegel, and appears somewhat in the ambiguous position of a sceptic anxious to believe. He sees insoluble contradictions in every mode of conceiving God as real, yet he advocates religious

belief, though the object of that belief have but an abstract or imaginary existence.

VACQUERIE, AUGUSTE (1819-1895), French journalist and man of letters, was born at Villequier (Seine Inférieure) on the 19th of November 1819. He was from his earliest days an admirer of Victor Hugo, with whom he was connected by the marriage of his brother Charles with Leopoldine Hugo. His earlier romantic productions include a volume of poems, L'Enfer de l'esprit (1840); a translation of the Antigone (1844) in collaboration with Paul Meurice; and Tragaldabas (1848), a melodrama. He was one of the principal contributors to the Événement and followed Hugo into his exile in Jersey. In 1869 he returned to Paris, and with Paul Meurice and others founded the anti-imperial Rappel. His articles in this paper were more than once the occasion of legal proceedings. After 1870 he became editor. Other of his works are Souvent homme varie (1859), a comedy in verse; Jean Baudry (1863), the most successful of his plays; Aujourd'hui et demain (1875); Futura (1900), poems on philosophical and humanitarian subjects. Vacquerie died in Paris on the 19th of February 1895. He published a collected edition of his plays in 1879. VACUUM-CLEANER, an appliance for removing dust from carpets, curtains, &c., by suction, and consisting essentially of some form of air-pump drawing air through a nozzle which is passed over the material that has to be cleaned. The dust is carried away with the air-stream and is separated by filtration through screens of muslin or other suitable fabric, sometimes with the aid of a series of baffle-plates which cause the heavier particles to fall to the bottom of the collecting receptacle by gravity. In the last decade of the 19th century compressed air came into use for the purpose of removing dust from railway carriages, but it was found difficult to arrange for the collection of the dust that was blown out by the jets of air, and in consequence recourse was had to working by suction. From this beginning several types of vacuum cleaner have developed.

VACUUM TUBE. The phenomena associated with the passage of electricity through gases at low pressures have attracted the attention of physicists ever since the invention of the frictional electrical machine first placed at their disposal a means of producing a more or less continuous flow of electricity through vessels from which the air had been partially exhausted. In recent years the importance of the subject in connexion with the theory of electricity has been fully realized; indeed, the modern theory of electricity is based upon ideas which have been obtained from the study of the electric discharge through gases. Most of the important principles deduced from these investigations are given in the article (Through Gases); here we shall confine ourselves to the consideration of the more striking features of the luminous phenomena observed when electricity passes through a luminous gas.