TROCHILUS, the humming bird, in na tural history, a germs of birds of the or der Picx. Generic character : bill slen def and weak ; nostrils'ininute ; tongue long,. constituted of two united cylindric tubes, and missile; tail of ten feathers ; legs weak. The bills of some ate curved, and ofotliers strait, which fbrms the grand division of the genus. There are sixty species enumerated by Latham, and Gmelin has sixty-five. by birds of this genus are the smallest of all birch. Thty subsist many of them on the juices of flowers, which they like tiles while, on the wing, fluttering-over theie delicate repast, and making a considera ble humming sound, frotn^ which they derive their designation. They are gre garious, and build their nests with great neatness and elegance, lining them with the softest materials they -can possibly procure.
T. colubris, or the red-throated hum ming bird, is rather more than three inches long, and is frequent in various parts of North America. plumage is highly splendid and varying ; it subsists on the nectar of flowers, particularly those of a long tube,.like the convolvulus or tulip. They will suffer themselves to be approached very nearly ; but on ob serving an effiart to seize' them, dart off with the rapidity of an arrow. A flower is frequently the subject of bitter conflict between two of these birds ; and they will often enter an open window, and after a short contest retire. They sometimes soar perpendicularly to a considerable height, with a violent scream. If a flower which they enter furnishes them with no supply, they pluck it, as it were in pun.
ishment and revenge, from its stalk. They have been kept alive in cages- for several weeks, but soon perish for want of their usual food, for which no adequate substi tute has yet been found Latham, how ever, mentions the curious circumstance of their being preserved alive by Cap tain Davies lier four months, by the expe dient of imitating tubular flowers with paper, appropriately painted., the bottom of the tubes with sugar and water as often as they were'emptied They then took their nourislum nt in the same manlier as when finorvilined, and soon appeared familiarized and happy. They lived, however, only flair months. These birds generally build on the middle .of the branch of a tree, ain't lay two eggs exteerne* small and admirably construct ed nest. This is the only species of the gennsknown to exist in the Utrited States.
T. minimus. This ig the smallest of all the species, and is said,' when just killed, to weigh more than twenty grains. Its totalvitength is an hitch and a quarter. It is fOund in the West Indies and South Amoricla arid is exceeded both in •eight'and magrittude by several species of bees.
For the ametisystine 'humming-bird, *e Arts, Plate Nth'. fig. 3. • TtfOCI-ILEA, one of the mechanical powers, usually called a pulley. See MECHANICS.
lisitOCHOID, in geometry, a curve Mere generally known by the name of cycloid. • See CYCLOID.