Page:The American Cyclopædia (1879) Volume I.djvu/523

 ANEMOSCOPE ANEURISM 491 that organ. Pulsatilla is a much used remedy in the homoeopathic materia medica. ANEMOSCOPE (Gr. ave/iof, wind, and OKOTTEIV, to look), a wind indicator, or weathercock. The term is, however, only applied when the weathercock is attached to a spindle which passes from the vane into an apartment below, and there by an index upon a compass dial in- dicates in what direction the wind blows. For expressing this direction the plan has been adopted of dividing the great circle of the hori- zon into 32 parts of 11 15' each, and calling the directions of the wind successively : N., N. by E., N. N. E., N. E. by N., N. E., N. E. by E., E. N. E., E. by N., E., E. by S., E. S. E., S. E. by E., S. E., S. E. by S., S. S. E., S. by E., S., S. by W., S. S. W., S. W. by S., S. W., S. W. by W., W. S. W., W. by S., W., W. by N., W. N. W., N. W. by W., N. W., N. W. by N., N. N. W., N. by W., N. The latest im- provement of the anemoscope is to attach a recording clockwork to the dial plate, so that not only the direction of the wind, but the time that it blows in any direction, is perma- nently recorded. Such an arrangement is now in operation at the meteorological observatory in the Central Park, New York. AMvKIO. I. Felice, an Italian musician, born in Kome about 1560, died about 1630. In 1594 he succeeded Palestrina as composer of the pontifical chapel. A great number of his compositions have "been published, and his un- published pieces have been preserved in the archives of the basilica of the Vatican and in the pontifical chapel. II. Giovanni Francesco, brother of the preceding, born in Rome about 1567, was for many years chapel master of the king of Poland and of the cathedral of Verona, and subsequently a teacher of music at the Ro- man seminary. He was one of the first Italian composers who made use of quavers, semi-qua- vers, and demi-serni-quavers. Many of his musical compositions have been published. ANEROID. See BAROMETER. ANEURIN, a Welsh bard, who was the leader of the mediaeval Britons in the battle of Cat- traeth, and who celebrated in heroic verse the deeds of that day. His work is still, preserved in the literature of Wales. He died about 570. It is supposed that this poet was either identi- cal with or the brother of the historian Gildas. ANEURISM (Gr. avevpvapdi;, a widening or ex- tension), a term used in surgery to signify a vascular tumor or enlargement, arising from the morbid distention of an artery It is much more common in some arteries than others, but any artery of the body is liable to it. The cor- responding disease and enlargement of a vein is termed varix. An artery is composed of three coats or membranes which form the walls of a strong, elastic, and distensible tube. In a healthy state, the tube maintains a certain di- ameter under the ordinary impulse of the blood ; but when the walls of an artery become dis- eased, they yield before the constant pressure of the circulating fluid, causing the diseased part to form a bag or tumor. This bag en- larges as the diseased walls distend ; and the inner and middle coats, being less resisting than the outer, especially in a diseased state, give way and burst, leaving the outer coat alone to form the walls of the aneurismal tumor. This admits of a considerable amount of distention ; but it eventually bursts, and then the unre- strained current gushes out with violence, and the patient dies from loss of blood. Sometimes, however, the dense cellular sheath of the arte- ry, though very distensible, is strong enough to retain the blood for a time after the rupture of the proper walls of the artery, and the aneuris- mal sac may thus be very much enlarged, and not give rise to fatal haemorrhage. At times, in fact, this external sac allows the ruptured walls within to partially collapse ; the current flows as usual ; the blood in the external sac coagulates and forms a clot around the ruptured part beneath ; the clot increases from its stag- nant state outside the current, and eventually plugs up even the ruptured parts, extending into the diseased artery and plugging up the tube, thus forcing the current to flow more abundantly through collateral channels, enlarg- ing the walls of neighboring arteries, and form- ing a spontaneous cure for the original disease. This is a very rare occurrence. The tumor usually enlarges by degrees, pressing upon the nerves and tissues near it, and causing pain as well as absorption of the soft or bony struc- tures against which it presses. An aneurismal tumor always pulsates strongly, and can gen- erally be distinguished from all other tumors by this characteristic feature. It sometimes happens, however, that an artery pulsating be- neath an abscess or an ordinary tumor causes the latter to simulate to some extent this pul- sating character, and hence arise at times errors of diagnosis of a serious character ; real aneurisms have been mistaken for abscesses lying upon a pulsating artery, and when opened under this impression to let out pus, the blood has gushed out from an aneurismal tu- mor, and the error has proved fatal. Ruysch relates that a friend of his opened a tumor near the heel, not suspecting it to be an aneurism, and the haemorrhage, though stopped at last, placed the life of the patient in great danger. Boerhaave was consulted by a patient on a swelling of the knee, and, suspecting it to be an aneurism, cautioned him against having it opened ; but it was opened by another person, and the man died on the spot. It is said that Ferrand, the head surgeon of the Hotel Dieu-in Paris, mistook an axillary aneurism for an ab- scess, plunged his bistoury into the swelling, and killed the patient. Such mistakes, how- ever, can hardly happen now, as all the best works on surgery give ample instructions on the means of diagnosis in this and other impor- tant diseases. The cure of aneurism consists in the obliteration of the diseased portion of the artery, by passing a ligature around the sound portion of the vessel at some distance