These expeditions and many others of lesser import, operating for the most part in seas remote from the countries in which they were fitted out, have contributed much of the literature of oceanography in which we find set forth the dynamic meteorology and climatology of the ocean, the theories of the tides and waves and the observed facts concerning them, the depths of the ocean, the temperature, the composition and circulation of oceanic waters, the nature and distribution of marine organisms at the surface and in the depths, and the origin and distribution of marine deposits over the floor of the ocean. But the ocean is so vast that the accumulation of facts of observation concerning it-extensive though it beis but a sparse array in geographical distribution and constitutes but a skeleton of knowledge in relation to the configuration of its basins, the nature and distribution and thickness and stratification of the deposits which cover the bottom, and the physical and chemical properties and movements and mode of operation of its waters in producing their effects in the economy of the earth.

It is not alone through expeditions upon the ocean that oceanography has progressed; investigations in marine laboratories and institutions of research and discoveries in cognate sciences have sometimes yielded more advancement than distant and perilous voyages.

Advancement in the nature of the application of the philosophy of method has enabled oceanography to profit in its later stages of development. The system according to which progress is now being sought is the study in detail of definite stations in the ocean occupied in concert, ́and, as we hope it will be, by international coöperation, and periodically revisited for the purpose of observing the variations of physical condition whose import, when it comes to be understood, will enhance all those wealth-producing sources which operate in seasonal cycles. Observa

tions of temperature, salinity, gas content, and currents made as nearly as possible at the same instant at series of points or stations and throughout a network of lines distributed in the depths beneath a given area of the ocean, and repeated every three months have afforded the means of making synoptic charts which disclose the existence of bends or undulations like the waves formed on the boundary surface between water layers of different densities. It is the mathematical investigation of the variations with time of the changing network of lines of equal values of the physical elements in their distribution in the depths that promises to introduce oceanography into the ranks of the exact sciences by enabling oceanographers, by mathematical laws, to predict effects from a few observations strategically placed.

Conspicuous among the features of the resumption of American oceanographical operations, after the interruption occasioned by the exigencies of the late times, are the following: The International Ice Observation and Ice Patrol Service in the North Atlantic Ocean, employing the vessels of the United States Coast Guard under an arrangement by which the cost is shared proportionately by the nations participating in the London Conference of 1913, is engaged (coördinately with the primary duties of ascertaining the locations and progressive movements of the limiting lines of the regions in which icebergs and field ice exist in the vicinity of the Grand Bank of Newfoundland and the dissemination of the information so ascertained for the guidance and warning of navigators) in gathering an important accumulation of oceanographical and meteorological observations. Year by year, observations at recorded times, extending from the surface to the bottom, are made in well determined geographical positions throughout the patrolled region for determining the temperature and salinity of the water by readings in series at definite depths, the direction and rate of movement of the waters in the different depths, the collection and preservation of plankton and samples of the water from ascertained depths, and in recording the state of the weather and the sea together with the barometric pressure, the humidity and the temperature of the air. These observations are published annually in the Bulletins of the United States Coast Guard, Treasury Department.

Closely related to these investigations from the standpoint of the advancement of oceanography, is the accumulation of observations resulting from the annual returns of the schooner Grampus in the Gulf of Maine and its vicinity, for the study of the correlation between physical oceanography and biological oceanography in these waters, under the joint auspices of the United States Bureau of Fisheries and the Museum of Comparative Zoölogy of Harvard University.

At La Jolla, near San Diego, California, there has grown up an institution by the name of the Scripps Institution for Biological Research, whose operations, recently brought under the auspices of the University

of California, constitute an exemplar of intensive oceanographical investigation. By systematically and repeatedly tabulating and mapping standardized values of the temperature, salinity, density, currents, and gas content of the water of the Pacific Ocean, serially observed at ascertained intervals of depth from the surface to the bottom in fixed locations, the variations of these physical elements, with time and locality, in their distribution in the depths, have been revealed to an important extent within the confines of the oceanic tract in the region of the seat of the Institution, stretching from San Diego to Point Concepcion and embracing an area of more than 10,000 square miles.

It is the present purpose of the Section of Physical Oceanography to foster the labors of these agencies and the similar ones which are contributed by the Navy and the Coast Survey and to seek opportunities to supplement them and link their operations, as far as may be, into coördination with the operations of the oceanographers of Japan, of Australia and New Zealand, of the North Sea International Council of Exploration, and the Mediterranean Sea International Council of Exploration. And, through the formation of committees, to provide that consideration shall be given to the problems of evaporation and heat transference and the interrelations between oceanography and meteorology, to the problems of dynamic oceanography including the variations of mean sea-level and the tides and their manifestations in the depths as well as the surface, to the investigation of the chemical and physical properties of the waters including the penetration of light, to the investigation of the origin and distribution of bottom deposits, to the problem of ascertaining the conformation and topography of the basins, and to the ways and means of advancement in the domain of physical oceanography.

THE PROBLEMS OF VOLCANOLOGY

BY HENRY S. WASHINGTON

INTRODUCTION

Of the various sciences represented in the American Geophysical Union that of volcanology is perhaps the most complex and has probably most points of contact with the other geophysical sciences. This complexity and variety in the problems presented by the study of volcanoes arises, in part, from the fact that they are, as has been well said, "natural laboratories." Also the distribution and many of the activities of volcanoes are closely connected with some of the physical, as well as the chemical forces that are involved in the formation and in the present condition of the earth.

In presenting some of the main problems of volcanology, we may begin with those that are essentially and more purely volcanological, and

then take up seriatim the consideration of certain problems in which the other sciences represented by sections of the Union may enter. Because of the limitation of space only a brief enumeration and presentation will be made, and no adequate discussion will be undertaken. I am much indebted to various members of the Union for some valuable suggestions, which will be mentioned in their proper places.

VOLCANOLOGY

A word may be said as to the name of the science. The spelling, volcanology, (rather than vulcanology), has been adopted officially by the Executive Committee of the Union, following the report of a sub-committee. The decision was arrived at chiefly in accordance with the dictum of the Century Dictionary (s. v. vulcanism): "The words volcano and volcanic are firmly fixed in English, and the former is in universal and exclusive use among those who speak that language. Hence all the derivatives should be spelled accordingly."

It is now well recognized that there are different types of volcanoes, distinguished by their form and structure, as well as (generally) by the differing kinds of volcanic activity, and that these differences are to a large degree dependent on, or at least coincident with, the differing chemical types of the volcanic material, such as, for instance, whether rhyolitic, andesitic, or basaltic. It follows that the activity or form of any one volcano, such as Vesuvius, Kilauea, or Stromboli, cannot be taken as typical of all volcanoes generally. This important principle does not seem to be generally recognized.

One of the first and most fundamental needs for the proper study of volcanoes is the compilation of a complete and fairly detailed catalogue of volcanoes (suggested by Wood and the writer). Such a catalogue should list all known active, dormant, or recently extinct volcanoes. It should give briefly, so far as known or ascertainable, the geographical position; the hypsometrical and areal data, including those of the crater; the general petrographical characters of the lavas, with the general order of succession of the different types; whether active, dormant, or extinct, with the geological period of commencement if possible; the general types of volcanic activity; a chronological list of the known eruptions, with some indication of the degrees of intensity; and a bibliography of the chief sources of information as to each volcano; with possibly such other data as may present themselves.

The older lists, as those of Daubeny (1848), Landgrebe (1855), Scrope (1862), and Fuchs (1865), are far from being complete; while even the more recent ones, such as that of Mercalli (1907), though they list many volcanoes not known to the earlier volcanologists, are yet themselves not complete, nor do they give many of the varied data mentioned above as desirable. The compilation of such a catalogue might be entrusted to a special committee.

on.

Another great desideratum is the keeping of a systematic record of all known volcanic events, eruptions, indications of renewed activity, and so This should be as complete as possible, and might be compiled by another, or the same, special committee, possibly with the assistance of some news-clipping bureau and correspondents at various volcanoes. In such a record, and in all other official volcanological literature, the sensational features should have a minimum of stress laid upon them.

If possible, some systematic investigation of the little known volcanoes and volcanic regions should be undertaken. This applies especially to those of the islands in the Pacific and Atlantic Oceans, and Daly, in an important paper, has called attention to the paucity of our knowledge as to the first of these. It is possible that such an investigation may be started by the coming Pan-Pacific Congress at Honolulu, at which the scheme will probably be proposed. For this purpose the assistance and coöperation of intelligent persons living in, or trading among, the various islands may be obtained, as well as, possibly, that of some private expeditions. Even the collection of chance specimens from the little-known islands would be of great value.

In this connection it may be suggested that the early history of our own western volcanoes should be investigated, as by search through the records of the early explorers and settlers, for possible mention of volcanic activity, and the verification or disproof of some such reported occurrences. The lavas of these volcanoes are well known, but the character of their volcanic activity has been much neglected.

Apart from the purely scientific question as to how and why a volcano "works," is the practical, and scientifically equally interesting, one of the prediction of eruptions. Unfortunately, with two or three exceptions, we know of volcanic activity almost entirely as displayed only during eruptions, and especially major ones. It is much like studying a complicated machine only when it is working at full speed; we can understand better the relations of the parts and their working if the machine is examined when the parts are moving slowly or are at rest.

For the prediction of eruptions, and for the solution of many other volcanological problems, prolonged, continuous, and systematic observations on volcanoes are absolutely necessary, not only during eruptions, but during the quiet intervals that precede and follow eruptions. Such observations have been carried on at Vesuvius, at first by Mercalli from 1892 to 1906, and by Malladra from about 1912 to the present time. Similar observations have also been carried on for nearly ten years at Kilauea by Jaggar, at times with the assistance of Perret, and Wood. It is hoped that the very detailed observations of Malladra will soon be published; they will form an invaluable contribution to volcanology. The records of the Kilauea observing, kept by Jaggar since 1911, are especially full and detailed and constitute what would be, if published, one of the