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Rh The total number of men supplied by Cleveland to the U.S. armies in the World War was 55,000; the total amount subscribed in the Liberty and Victory Loans $437,041,300. (H. E. B.)

CLIFFORD, JOHN (1836- . ), British Nonconformist divine (see 6.507), resigned his position at Westbourne Park chapel in 1915. He was president of the National Brotherhood Council from 1916 to 1919.

CLIMATE AND CLIMATOLOGY (see 6.509). In climatological progress during 1910-21 certain general tendencies are observable, (i) Increasing emphasis has been laid upon applied, as distin- guished from theoretical, climatology. Practical climatology is essentially human and economic. The investigation of its life- relations is the most important subject with which climatology has to deal. (2) More attention is being paid to the variability, the frequency, and the probability of occurrence of the various climatic elements, with correspondingly less limitation to simple mean or average values. Mathematical treatment of climatic data along well-established lines, such as the use of frequency curves, and of coefficients of correlation, is becoming more general with the result that the whole body of climatological knowledge is more precise and of greater practical value. (3) In most of the recent publications on climatography the fact is recognized that, climate being average weather, no vivid and accurate picture of any climate can be gained merely from a statistical tabulation of the ordinary climatic elements. It is necessary to have also clear and interesting descriptions of the various weather types. The addition of such descriptions has resulted in a distinct gain in the more thorough understanding of climates, especially in their relations to man. For years, one of the most significant sections of British Rainfall has been Dr. H. R. Mill's discussion of the occurrence of heavy rainfalls in relation to the actual storm conditions which brought them. Such studies have also recently been carried out in other countries.

The outstanding general text and reference book on all aspects of climatology is the 3rd edition, in three volumes, of Dr. Julius von Hann's Handbuch der Klimatologie. 1 These volumes con- stitute the one indispensable handbook for all who are in any way concerned with the study of climate. The first volume (1908) deals with general climatology. The second (1910) and third (1911) volumes are devoted to climatography. In them, a summary of what is known concerning the climate of every part of the world may be found. The climatic pictures are made notably complete and accurate by means of vivid descriptions of weather types; by frequent reference to the effects of climate upon vegetation, upon crops, and upon human activities, and by well-chosen quotations from the writings of residents and of travellers who are familiar with the climates concerning which they have given accounts. Temperature, rainfall and other essential data for large numbers of stations, in many cases here worked out in detail and summarized for the first time, constitute a very valuable feature of the book. All important literature up to the date of publication of the Handbuch is cited. References to more recent literature will be found in the regular meteoro- logical bibliographies.

Classification of Climates. In the systematic study of the world's climates, some scheme of classification must be employed. Many such classifications have been suggested, some based on a single element of climate and others on various combinations of these elements. The late Dr. A. J. Herbertson, whose " major natural regions " are well known, made a later study of " thermal regions," using certain critical actual temperatures (68, 50, 32 F.) and con- structing maps which show the numbers of months during which these temperatures prevail.*

The duration of these Critical temperatures is of importance in the distribution and growth of vegetation, and therefore also in the life of man. A more elaborate scheme of classification has been suggested by Koppen. 3 This is a thorough revision of the classifica- tion proposed by him in 1900.

1 J. von Hann, Handbuch der Klimatologie, 3rd ed., Stuttgart, vol. i., 1908; vol. ii., 1910; vol. iii., 1911.

8 A. J. Herbertson, " The Thermal Regions of the Globe," Geog. Journ., vol. xl., 1912, pp. 518-532.

Niederschlag und Jahresverlauf," Pet. Mitt., vol. Ixiv., 1918, pp. 193-203, 243-248.
 * W. Koppen, " Klassifikation der Klimate nach Temperatur,

The critical features of the controlling factors are worked out with great accuracy and detail. A brief, simple scheme of two or three reference tetters and numbers (climatic formulae) is used for the characterization of each climatic subdivision. As a framework for comparative studies of climates and of climatic controls the new map is of great value.

In studies of the general controls exercised over seasonal weather conditions, and hence also over climates in all parts of the world, the publication of the Roseau Mondial is of great significance. 4 This is a compilation of world data by 10 squares of lat. and long., based on observations at land stations averaging two for each square. Monthly and annual summaries of pressure, temperature and precipitation are included, with charts for the year 1911.

Another general publication of broad climatic interest is a study of the snow-line. 5 The snow-line is the resultant of climatic and topographic controls. An analysis of the observations of the snow- line is therefore an important subdivision of climatology. Nearly two-thirds of this monograph is taken up with a detailed summary and a critical examination of the data from all parts of the world, with copious references to the sources of information.

Variations of Climate. The whole question of climatic variations is still under active debate, both as to the occurrence, characteristics and frequency of any such " changes," and also as to their possible causes. Dr. Ellsworth Huntington has been the most prolific writer on this problem. His investigations, which began in central Asia, have been extended over parts of western Asia, Palestine, the Libyan Desert, the southwestern United States and portions of Central America. 6

From an examination of a large body of evidence archaeological, physiographic, historical including the rings of the giant Sequoias of California, the conclusion is drawn that from the beginnings of human history a gradual change from moister to drier climates has been going on. This process has, however, not been steadily pro- gressive, but has taken place in a more or less irregular pulsatory fashion, drier and moister epochs alternating without definite period- icity as subordinate irregularities on the general curves of desicca- tion. The major fluctuations are believed by Huntington to have been essentially synchronous, and of the same general character under similar geographic conditions, in central and western Asia, in the Mediterranean area, and in North America. These pulsations are further believed to have been potent factors in bringing about certain great historical migrations and events, such as, e.g., the de- cline of Persia, the barbaric invasions, the decay of Rome, the rise and fall of Central-American civilization, etc.

While much evidence in favour of changes of climate in historic times has been brought forward, the opinion is quite widely held that a good deal of this is not wholly trustworthy. Much of it is so distinctly contradictory that in certain cases nothing less than a complete deadlock exists. Further, it is held by a considerable num- ber of meteorologists that much of the evidence seems to have been interpreted without due consideration of controls other than climatic fluctuations. In cases where careful examination of the evidence has been made by experts in archaeology, botany, geology and history, there has usually been hesitation in ascribing the facts solely, or often even partly, to fluctuations in climate.

There have been several critical studies of the evidence concerning fluctuations in climate within historical times, such as those by J. W. Gregory, 7 Hildebrandsson* and Berg. 9 It seems, at the present time, to be the general consensus of the most expert meteorological judgment that there is not as yet sufficient unimpeachable evidence to justify a belief in any progressive change of climate within historic times. That there are certain fluctuations in the values of the climatic elements is, however, a well-established fact. The so- called Bruckner period, averaging about 35 years in length, is gen- erally recognized. No definite or universally accepted conclusion has yet been reached regarding the existence of other longer periods. A period of about II years in temperature, rainfall, and certain other meteorological phenomena has been made out by several investigators. On the whole, the variations in the values of these elements have appeared to be very slight, and the results are often debatable, if not contradictory. Koppen has greatly extended his investigations of sunspot controls over temperatures, begun some

4 Reseau Mondial, 1911, Tables and Charts; 1912, 1913, Tables without charts, Meteorological Office, London.

'Viktor Paschinger, " Die Schneegrenze in verschiedenen Klimaten," Erganzungsheft, No. 173, Pet. Mitt., 1912.

6 Ellsworth Huntington, Palestine and its Transformation, 1911; " The Climatic Factor as Illustrated in Arid America," with chapters by Charles Schuchert, Andrew E. Douglass and Charles J. Kullmer, Carnegie Inst. Publ. No. 192, Washington, D.C., 1914. (Also numerous other articles.)

7 J. W. Gregory, " Is the Earth Drying Up?" Geog. Journ., vol. viii., 1914, pp. 148-172, 293-318.

8 H. H. Hildebrandsson, " Sur le Pretendu Changement du Climat Europeen en Temps Historique," Nova Acta Regiae Societatis Scientiarum Upsaliensis, Ser. IV., vol. iv., No. 5, Upsala, 1915.

8 L. Berg, " Das Problem der Klimaanderung in geschichtlichet Zeit," Geog. Abhandl., vol. x., No. 2, Leipzig, 1914.