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240 VACA is A/on. V aa & numeral denotes 5, or with a dash over it (y), 500. On old French coias it signifies the mint of Troyes. VACA, Cabe?a de. See NUSEZ, ALVAB. VACCAJ, Nieolo, an Italian composer, born at Tolentino in the Papal States in 1791, died in Milan in 1849. He was a pupil of Paisiello at Naples, and from 1811 to 1820 wrote operas, cantatas, and ballets, which had a moderate success. He then taught singing in Venice, Trieste, and Vienna, and wrote Pietro il Grande, a comic opera performed at Parma, Zadig ed Astartea, performed at Naples, and Oiulietta e Romeo, performed at Milan, his best work. He afterward taught singing in Paris and London, but returned to Italy in 1832, and in 1838 became first master of com- position at the conservatory f Milan, which post he held till his death. VACCARO, Andrea, an Italian painter, born in Naples in 1598, died there in 1670. Ho was a pupil of Stanzioni, after whose death he was at the head of the Neapolitan school. One of his best works is a "Holy Family" in the church of Santa Maria degli Angeli at Naples. VACCINATION (Lat. vacca, a cow), inoculation for cowpox as a protection against smallpox, first practised by Dr. Edward Jenner in 1796. (See JESTNER.) On the 2d or 3d day after virus taken from a perfect vaccine vesicle, whether from the cow or the human subject, is placed in contact with the denuded dennis or true skin, the puncture is observed to be slightly inflamed. On the 4th or 5th day a vesicle is observed surrounded by a slight blush of in- flammation, and containing a little colorless, transparent fluid. This increases until the 8th day, when it should be from a quarter to half an inch in diameter, the blush of inflammation sur- rounding it at the same time having become more marked. The vesicle is umbilicated, that is, its centre is depressed below the level of the circumference, in this respect resembling the pustules of smallpox. It is compound, being made of 10 to 14 distinct cells ; one of these, carefully punctured, discharges a minute drop of fluid, leaving the other cells still dis- tended. On the 8th day the blush of sur- rounding inflammation, heretofore very slight, begins to extend, forming what is termed the areola ; it attains its greatest diameter by the llth day, after which it gradually fades and disappears. With the appearance of the areola the vesicle becomes darker and dryer, and gradually concretes into a brown translucent crust, which falls off about the 20th day, leav- ing a circular depressed cicatrix. About the 8th or 9th day there is usually some slight fe- brile disturbance, though it is often scarcely noticeable. Such is the course of the true vac- cine vesicle when uninterfered with, either by the presence of constitutional disease or by the accidental occurrence of inflammation. When vaccination was first introduced, it was believed that it would afford in all cases complete and permanent protection from smallpox. But it VACHEROT was discovered that those who had been well and thoroughly vaccinated were still liable to some extent to attacks of smallpox ; and though in general the disease was modified (varioloid) and rendered shorter and milder, still it occa- sionally resulted in death. The degree of pro- tection afforded by vaccination thus became a question of great interest. Its extreme value was easily demonstrated by statistical researches. In England, in the last half of the 18th century, out of every 1,000 deaths, 96 occurred from smallpox ; in the first half of the present century, out of every 1,000 deaths, but 35 were caused by that disease. The amount of mortality in a country by small- pox seems to bear a fixed relation to the ex- tent to which vaccination is carried out. In all England and Wales, for some years previous to 1853, the proportional mortality by small- pox was 21 '9 to 1,000 deaths from all causes; in London it was but 16 to 1,000; in Ireland, where vaccination was much less general, it was 49 to 1,000, while in Connaught it was GO to 1,000. On the other hand, in a number of European countries where vaccination was more or less compulsory, the proportionate number of deaths from smallpox about the same time varied from 2 per 1,000 of all causes in Bohemia, Lombardy, Venice, and Sweden, to 8 - 33 per 1,000 in Saxony. Although in many instances persons who had been vac- cinated were attacked with smallpox in a more or less modified form, it was noticed that the persons so attacked had been commonly vacci- nated many years previously. The mere lapse of time in many cases seems sufficient to de- stroy the protective influence of vaccination. The duration of the protective influence varies with different individuals. The same thing happens with regard to the protective influ- ence of an attack of smallpox itself ; in most persons it lasts for life ; many, after a period more or less prolonged, are liable to a second attack ; while cases have occurred in which a third attack has proved fatal. In all cases revaccination seems to be a test of the loss or presence of the protective influence ; to render this test certain, where revaccination does not succeed on the first trial, it should be careful- ly performed a second time. In the Prussian army in 1848, 28,859 individuals were revac- cinated, in 6,373 of whom the cicatrices of the preceding vaccination were indistinct or invisi- ble. Of these, 16,862 had regular vesicles, 4,404 irregular vesicles, and in 7,753 cases no effect was produced. On a repetition of the vaccination in these last, it succeeded in 1,579 cases. Among the whole number successful- ly revaccinated either in 1848 or before, there was but a single case of varioloid, and not one case of smallpox ; while seven cases of vario- loid occurred either among the recruits or among those revaccinated without success. VACHEROT, i-:tir;:ic, a French philosopher, born in Langres, July 29, 1809. He studied at the normal school in Paris, and was director