Page:Encyclopædia Britannica, Ninth Edition, v. 11.djvu/796

760 the next fifteen years in rapid succession it is unnecessary to give a detailed account. Only the names of some of the more important may be mentioned here :--La Cluchette (1817), L’Auteur mort et vivant (1820), Maurie (1826), and the ballets Za Fille mal Gardée (1828) and La Belle au bois dormant (1829). Heérold also wrote a vast quantity of piano- forte music of a more or less ephemeral kind, in spite of his time being much occupied by his duties as accompanist at the Italian opera in Paris. In 183] he produced one of the two works which have given immortality to his name, the romantic opera Zempa, which has met with immense success not only in France but also in Germany, where it has kept the stage till the present day, and is considered Heérold’s masterpiece. In France that eminence is justly accorded to the Le Pré aux Cleres (first performance December 15, 1832), in every way a representative work of the French school, in which French esprié and French chivalry find their most perfect embodiment. Grace, liveliness, and true dramatic spirit are Hérold’s best qualities, and secure him a promi- nent place amongst the composers of opéra comique, in the more refined sense which has been lost by most composers of modern France. Herold died January 19, 1833, of the lung disease from which he had suffered for many years, ani the effects of which he accelerated by incessant work.

 HERON, or, a mathematician and natural philosopher of Alexandria, was the pupil of Ctesibius, and flourished probably about a century or a century and a half before Christ. His name has been preserved in the well-known experiment of Hero’s fountain, in which, by means of condensed air, water is made to spring from a jet in a continuous stream. Several of Heron’s writings are entirely lost, and of those that remain some have never been printed. His most valuable work is that on Pneumatics, in which are given his experiments on the elasticity of the air and of steam. His Mechanics and Barulcus treat of the subjects which would now be comprised in an elementary book on dynamics. At the end of his Catapeltwa or Belopotetica, which are probably the same, occurs Heron’s solution of the ancient and much discussed problem to find two mean proportionals between two given straight lines. Chetrobalistra, Cambestria, Camarica, Automata, are the titles of some of his other physical works. His mathematical works (see Hultsch’s //eronis Alexandrina Geometricorum et Stereometricorum Reliquice, Berlin, 1864) are very fragmentary, and it is difficult to determine whether several of them are not to be attributed to later and anonymous writers. Heron seems to have been the first to show how the area of a triangle may be found from its three sides. See two papers by Vincent and Boncom- pagni in Bulletteno de bibliogr. e dv storia delle scienze matem. e fisiche, iv.

 HERON, called the younger, to distinguish him from his namesake of Alexandria, was, like him, a mathematician and natural philosopher. By some he is supposed to have flourished in the ; by others, with more probability, to have lived at Constantinople in the. He wrote a treatise on Besieging Engines which still exists, and another on the Construction of Sun-dials, which is now lost. Some mathematical writings assigned to him should perhaps be referred to Heron the elder (see Alémoires Présentés a ?Académie des Inscriptions, 1®'¢ série, tome iv., Paris, 1854).

 HERON—French, Zféron; Italian, Agherone, Airone ; Latin, Ardea; Greek, épwétds; Anglo-Saxon, //ragra ; Ice- landic, Legre ; Swedish, dger; Danish, /feive ; German, Heiger, Reiher, Heergans; Dutch, Reiger—a long-necked, long-winged, and long-legged bird, the representative of a very natural group, the Ardecdw, which through the neglect or ignorance of ornithologists has been for many years encumbered by a considerable number of alien forms, belonging truly to the Cranes, Gruide (see ), and Storks, Ciceniide, whose structure and characteristics are wholly distinct, however much external resemblance some of them may possess to the Herons. Eliminating these intruders, it is difficult or even impossible to estimate with any accuracy the number of species of Ardeide which exist. Professor Schlegel in 1863 enumerated 61, besides 5 of what he terms “ conspecies,” as contained in the col- lection at Leyden (J/us. des Pays Bas, Arde, 64 pp.),— on the other hand, G. R. Gray in 1871 (//and-list, &e., ill. pp. 26-34) admitted above 90, while Dr Reichenow (Journ. fiir Ornithologie, \ST7, pp. 232-275) recognizes 67 as known, besides 15 “subspecies” and 3 varieties, arranging them in 3 genera, Mycticorar, Botaurus, and Ardea, with 17 subgenera. But it is difficult to separate the Family, with any satisfactory result, into genera, if structural characters have to be found for these groups, for in many cases they run almost insensibly into each other— though in common language it is easy to speak of Herons, Egrets, Bitterns, Night-Herons, and Boatbills, With the exception of the last, Professor Schlegel retains all in the genus Ardea, dividing it into eivht sections, the names of which may perhaps be Englished—Great Herons, Small Herons, Egrets, Semi-egrets, NRail-like Herons, Little Bitterns, Bitterns, and Night-Herons. It may be expe- dient here to adopt this arrangement, though the present writer would guard himself against being supposed to give it more than partial and provisional assent.

The common Heron of Europe, Ardea cinerea of Linnaus, is universally allowed to be the type of the family, and it may also be regarded as that of Professor Schlegel’s first section. The species inhabits suitable localities throughout the whole of Europe, Africa, and Asia, reaching Japan, many of the islands of the Indian Archipelago, and even Australia. Though by no means so numerous as formerly in Britain, it is still sufficiently common to render a deserip- tion of it almost unnecessary, and there must be few persons who have not seen it rising slowly from some river- side or marshy flat, or passing overhead in its lofty and 