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748 LYELL LYGODIUM instructive facts brought together from the ob- servations of the author and from others gath- ered from all parts of the world, for the clear and attractive style in which these were pre- sented, and more than all for the skill with which operations now going on were made to .explain those of past periods, and to account for the present condition of the surface of the earth. In successive editions the work so in- creased, that in 1838 the author divided it into two distinct treatises, retaining in one, which he called "Elements of Geology," the descrip- tion of the formations of past periods, and giving in the other, "The Principles," the de- scription of processes now going on by which the phenomena of the older formations are explained. In the edition of 1851 the "Ele- ments" appeared with the title of "Manual of Elementary Geology," which, after passing through many editions, was replaced in 18VO by his " Student's Manual of Geology." These works placed their author in the first rank among geologists, and gave to the science itself a new character, removing from it all depen- dence upon visionary speculations by showing how its principles should be deduced in the true system of inductive philosophy from well observed facts. In 1841 Lyell visited the Uni- ted States, having been invited to deliver a course of lectures on geology in Boston. He availed himself of the opportunity to travel over a large portion of the northern and middle states, and as far south as Kentucky, giving special attention to the geological features of the country, and learning also by intercourse with the geologists and naturalists of the sev- eral states the results of their investigations. He also studied the different institutions of the country, particularly those of learning ; and in a year thus spent in the United States, Can- ada, and Nova Scotia, he gathered a vast fund of information, some of the fruits of which are presented in his work entitled " Travels in North America in the years 1841-'2 " (2 vols., London, 1845; 2d ed., 1855). The scientific matter contained in this book was prepared chiefly for the general reader ; his more extend- ed observations were presented in numerous papers published in the "Proceedings" and "Transactions" of the geological society of London, the " Keports of the British Associa- tion," and the "American Journal of Science." This work contained the most complete geolo- gical map of the United States published up to that time, in the compilation of which Lyell was greatly aided by Prof. James Hall of Al- bany. In September, 1845, he again embarked for the United States, and remained in the country till June, 1846. He visited portions of the northern states which he had not before seen, and devoted nearly six months to a tour through the southern states. He examined the most interesting localities of the tertiary formations in the states bordering on the At- lantic and the gulf of Mexico, passed up the Mississippi river, making many observations of the deposits upon its banks and its influence as a geological agent, and in southern Missouri visited the sunk country of New Madrid dev- astated by the earthquake of 1811-'12. In 1849 he published "A Second Visit to the United States " (2 vols., London ; 3d ed., 1855). Everywhere his observations were extended beyond the geological structure of the country, and included the manners and customs of the people he met with, and their various institu- tions ; his criticisms upon these are expressed in a liberal and philosophical spirit. In the modern progress of geology Lyell's name is more identified with the arrangement of the tertiary formations than with any other de- partment. He first classified them into groups distinguished by the relative proportion of living and extinct species of fossil shells which they contained, and gave them the names of eocene, miocene, and pliocene, founded on this distinction, as described in the article GEOLOGY. He has investigated with special care those great natural phenomena in progress which involve long periods of time, and has under- taken to give approximate estimates of the time elapsed, based upon the results produced and the rate at which these are now proceed- ing. Thus, in visiting active volcanoes, he has sought to determine the age of the accumula- tions of lava from data afforded in modern times of their rate of increase. In examining the region of extinct volcanoes of central France, he applied the same method of reason- ing to show that vast periods must have elapsed while the successive volcanic and fluviatile de- posits were produced ; and in his second visit to the United States he found in the Missis- sippi river, and the great delta of its sediments deposited near the gulf, materials for another class of calculations of the same general char- acter. In 1863 appeared his " Geological Evi- dences of the Antiquity of Man," a work in which he brought together a great amount of research with regard to prehistoric times. Lyell had previously opposed the doctrine of development, but in this remarkable work gave his adhesion to the theories of Darwin on the origin of species. Lyell was elected president of the geological society in 1836 and again in 1850, knighted for his services to science in 1848, in 1855 received from Oxford the degree of D. 0. L., and in 1864 was created a baronet. LYGDAMIS, a tyrant of Naxos, born about 580 B. 0. He became a leader of the popular party in Naxos, and when they conquered the oligarchy he obtained the chief power. Du- ring his absence to assist Pisistratus on his third return to Athens, there was a revolution in Naxos; but Pisistratus subdued it and made Lygdamis tyrant of the island, about 540. Lyg- damis assisted Polycrates (532) in obtaining the tyranny of Samos; but a few years later he himself was put down, with other tyrants, by the Lacedaemonians. LYGODIUM (Gr. hvytidw, flexible), a genus of climbing ferns, with much divided leafy fronds,