sable water-supplies for large towns are secured by their aid. Engineers, however, also provide for the drainage of large towns and districts, the mitigation of inundations on low-lying lands, the reclamation of lands from the sea, and the irrigation of large tracts of land in warm countries by which crops are preserved and famine averted, and they carry out the works for the illumination of streets and houses with gas and electricity. To their credit also are improvements in marine engines and increased speed of ocean steamers, and improvements in telegraphy and the laying of submarine cables, and if engineers in the future continue as in the last half-century, increasing and extending the benefits resulting from their works, they will justly be regarded as ranking among the greatest benefactors of mankind."
The Oyster: A Popular Summary of a Scientific Study. By William K. Brooks. Baltimore: the Johns Hopkins Press. Pp. 230, with Plates. Price, $1.
Prof. Brooks is our most thorough and successful student of the oyster. He has devoted a large part of his time to the study for more than ten years past, and, as President Gilman says in the introduction to this book, "he can hold his own not only among naturalists, but also among practical men. He has dredged in every part of the [Chesapeake] bay. To use his own words, he has tonged oysters in five different States; in the warm waters of the South he has spent months under the broiling sun, wading over the sharp shells which cut his feet like knives, studying the oysters 'at home.' He has planted them, he has reared them by collecting the floating spat, and he has hatched from artificially fertilized eggs more oysters than there are inhabitants of the United States." He has also studied the experience of other States and countries, and has gathered up the knowledge of the world in respect to the life of the oyster, "its enemies and its needs, its dangers and its protections." The results of this practical work and these studies are embodied in the present book in familiar style and language for the information of the public. The whole work—studies and book—has been prompted by the fact, which is printed in capital letters, that "the demand for Chesapeake oysters has outgrown the natural supply." Prof. Brooks's effort has been to find a way to increase and supplement that supply. For this, his essay offers many suggestions of value.
Popular Lectures and Addresses. By Sir William Thomson. Vol. III. Navigational Affairs. London and New York: Macmillan & Co. Pp. 603. Price, $2.
Volume third of this serie3 of addresses precedes volume second in publication because considerable matter had been prepared on navigational subjects which were assigned to the third volume in the plan of the Beries, before any progress had been made with the geological lectures. The lectures included in this volume are one on Navigation, delivered to the Science Lecture Association; a British Association evening lecture on The Tides, with parts of a lecture before the Glasgow Association on the same subject; a British Association paper on the Influence of the Straits of Dover on the Tides of the British Channel and the North Sea, with appendixes on the tides of the southern hemisphere and the Mediterranean, and a sketch of a proposed plan of procedure in tidal observation and analysis, and on the equilibrium theory of the tides; and papers on Terrestrial Magnetism and the Mariner's Compass; Deep-sea Sounding by Pianoforte Wire; Lighthouse Characteristics; the forces concerned in the laying and lifting of deep-sea cables; and Ship Waves. To these is appended a concluding paper by Captain Creak, R. N., on the disturbance of ships' compasses by the proximity of magnetic rocks at considerable depth under wa. ter.
Natural Selection and Tropical Nature. By Alfred Russel Wallace. New edition, with Corrections and Additions. London and New York: Macmillan & Co. Pp. 492. Price, $1.75.
Many persons who have been interested by Mr. Wallace's Darwinism, and are not acquainted with his early works, will doubtless welcome this reprint of two volumes of his biological essays. These papers are popular enough to interest the general reader, while containing able discussions of impor-
