Part 10

Lastly, a region whose normal rainfall is at best barely sufficient for man's needs may be abandoned by its inhabitants during a few years of deficient precipitation, and not again occupied even when, a few years later, normal or excessive rainfall occurs.

_Periodic Oscillations of Climate: Sun-spot Period._--The discovery of a distinct eleven-year periodicity in the magnetic phenomena of the earth naturally led to investigations of similar periods in meteorology. The literature on this subject has assumed large proportions. The results, however, have not been satisfactory. The problem is difficult and obscure. Fluctuations in temperature and rainfall, occurring in an eleven-year period, have been made out for certain stations but the variations are slight, and it is not yet clear that they are sufficiently marked, uniform and persistent over large areas to make practical application of the periodicity in forecasting possible. In some cases the relation to sun-spot periodicity is open to debate; in others, the results are contradictory.

W. P. Köppen has brought forward evidence of a sun-spot period in the mean annual temperature, especially in the tropics, the maximum temperatures coming in the years of sun-spot minima. The whole amplitude of the variation in the mean annual temperatures, from sun-spot minimum to sun-spot maximum, is, however, only 1.3° in the tropics and a little less than 1° in the extra-tropics. More recently Nordmann (for the years 1870-1900) has continued Köppen's investigation.

In 1872 C. Meldrum, then Director of the Meteorological Observatory at Mauritius, first called attention to a sun-spot periodicity in rainfall and in the frequency of tropical cyclones in the South Indian Ocean. The latter are most numerous in years of sun-spot maxima, and decrease in frequency with the approach of sun-spot minima. Poëy found later a similar relation in the case of the West Indian hurricanes. Meldrum's conclusions regarding rainfall were that, with few exceptions, there is more rain in years of sun-spot maxima. S. A. Hill found it to be true of the Indian summer monsoon rains that there seems to be an excess in the first half of the cycle, after the sun-spot maximum. The winter rains of northern India, however, show the opposite relation; the minimum following, or coinciding with, the sun-spot maximum. Particular attention has been paid to the sun-spot cycle of rainfall in India, because of the close relation between famines and the summer monsoon rainfall in that country. Sir Norman Lockyer and Dr W. J. S. Lockyer have recently studied the variations of rainfall in the region surrounding the Indian Ocean in the light of solar changes in temperature. They find that India has two pulses of rainfall, one near the maximum and the other near the minimum of the sun-spot period. The famines of the last fifty years have occurred in the intervals between these two pulses, and these writers believe that if as much had been known in 1836 as is now known, the probability of famines at all the subsequent dates might have been foreseen.

Relations between the sun-spot period and various other meteorological phenomena than temperature, rainfall and tropical cyclones have been made the subject of numerous investigations, but on the whole the results are still too uncertain to be of any but a theoretical value. Some promising conclusions seem, however, to have been reached in regard to pressure variations, and their control over other climatic elements.

_Brückner's 35-Year Cycle._--Of more importance than the results thus far reached for the sun-spot period are those which clearly establish a somewhat longer period of slight fluctuations or oscillations of climate, known as the Brückner cycle, after Professor Brückner of Bern, who has made a careful investigation of the whole subject of climatic changes and finds evidence of a 35-year periodicity in temperature and rainfall. In a cycle whose average length is 35 years, there comes a series of years which are somewhat cooler and also more rainy, and then a series of years which are somewhat warmer and drier. The interval in some cases is twenty years; in others it is fifty. The _average_ interval between two cool and moist, or warm and dry, periods is about 35 years. The mean amplitude of the temperature fluctuation, based on large numbers of data, is a little less than 2°. The fluctuations in rainfall are more marked in interiors than on coasts. The general mean amplitude is 12%, or, excluding exceptional districts, 24%. Regions whose normal rainfall is small are most affected.

The following table shows the dates and characters of Brückner's periods:--

Warm 1746-1755 1791-1805 1821-1835 1851-1870 .. Dry 1756-1770 1781-1805 1826-1840 1856-1870 .. Cold 1731-1745 1756-1790 1806-1820 1836-1850 1871-1885 Wet 1736-1755 1771-1780 1806-1825 1841-1855 1871-1885

Interesting confirmation of Brückner's 35-year period has been found by E. Richter in the variations of the Swiss glaciers, but as these glaciers differ in length, they do not all advance and retreat at the same time. The advance is seen during the cold and damp periods. Brückner has found certain districts in which the phases and epochs of the climatic cycle are exactly reversed. These exceptional districts are almost altogether limited to marine climates. There is thus a sort of compensation between oceans and continents. The rainier periods on the continents are accompanied by relatively low pressures, while the pressures are high and the period dry over the oceans and vice versa. The cold and rainy periods are also marked by a decrease in all pressure differences. It is obvious that changes in the general distribution of atmospheric pressures, over extended areas, are closely associated with fluctuations in temperature and rainfall. These changes in pressure distribution must in some way be associated with changes in the general circulation of the atmosphere, and these again must depend upon some external controlling cause or causes. W. J. S. Lockyer has called attention to the fact that there seems to be a periodicity of about 35 years in solar activity, and that this corresponds with the Brückner period.

It is clear that the existence of a 35-year period will account for many of the views that have been advanced in favour of a _progressive_ change of climate. A succession of a few years wetter or drier than the normal is likely to lead to the conclusion that the change is permanent. Accurate observations extending over as many years as possible, and discussed without prejudice, are necessary before any conclusions are drawn. Observations for one station during the wetter part of a cycle should not be compared with observations for another station during the drier part of the same, or of another cycle.

There are evidences of longer climatic cycles than eleven or 35 years. Brückner calls attention to the fact that sometimes two of his periods seem to merge into one. E. Richter shows much the same thing for the Alpine glaciers. Evidence of considerable climatic changes since the last glacial period is not lacking. But as yet nothing sufficiently definite to warrant general conclusions has been brought forward.

_Geological Changes in Climate._--Changes of climate in the geological past are known with absolute certainty to have taken place: periods of glacial invasion, as well as periods of more genial conditions. The evidence, and the causes of these changes have been discussed and re-discussed, by writers almost without number, and from all points of view. Changes in the intensity of insolation; in the sun itself; in the conditions of the earth's atmosphere; in the astronomical relations of earth and sun; in the distribution of land and water; in the position of the earth's axis; in the altitude of the land; in the presence of volcanic dust;--now cosmic, now terrestrial conditions--have been suggested, combated, put forward again. None of these hypotheses has prevailed in preference to others. No actual proof of the correctness of this or that theory has been brought forward. No general agreement has been reached.

_Conclusion._--Without denying the possibility, or even the probability, of the establishment of the fact of secular changes, there is as yet no sufficient warrant for believing in considerable _permanent changes over large areas_. Dufour, after a thorough study of all available evidence, has concluded that a change of climate has not been proved. There are periodic oscillations of slight amount. A 35-year period is fairly well established, but is nevertheless of considerable irregularity, and cannot as yet be practically applied in forecasting. Longer periods are suggested, but not made out. As to causes, variations in solar activity are naturally receiving attention, and the results thus far are promising. But climate is a great complex, and complete and satisfactory explanations of all the facts will be difficult, perhaps impossible, to reach. At present, indeed, the facts which call for explanation are still in most cases but poorly determined, and the processes at work are insufficiently understood. Climate is not absolutely a constant. The pendulum swings to the right and to the left. And its swing is as far to the right as to the left. Each generation lives through a part of one, or two, or even three oscillations. A snapshot view of these oscillations makes them seem permanent. As Supan has well said, it was formerly believed that climate changes locally, but progressively and permanently. It is now believed that oscillations of climate are limited in time, but occur over wide areas.

LITERATURE.--Scientific climatology is based upon numerical results, obtained by systematic, long continued, accurate meteorological observations. The essential part of its literature is therefore found in the collections of data published by the various meteorological services. The only comprehensive text-book of climatology is the _Handbuch der Klimatologie_ of Professor Julius Hann, of the university of Vienna (Stuttgart, 1897). This is the standard book on the subject, and upon it is based much of the present article, and of other recent discussions of climate. The first volume deals with general climatology, and has been translated into English (London and New York, 1903). Reference should be made to this book for further details than are here given. The second and third volumes are devoted to the climates of the different countries of the world. Woeikof's _Die Klimate der Erde_ (Jena, 1887) is also a valuable reference book. The standard meteorological journal of the world, the _Meteorologische Zeitschrift_ (Braunschweig, monthly), is indispensable to any one who wishes to keep in touch with the latest publications. The _Quarterly Journal of the Royal Meteorological Society_ (London), _Symons's Monthly Meteorological Magazine_ (London), and the _Monthly Weather Review_ (Washington, D.C.) are also valuable. The newest and most complete collection of charts is that in the _Atlas of Meteorology_ (London, 1899), in which also there is an excellent working bibliography. For the titles of more recent publications reference may be made to the _International Catalogue of Scientific Literature (Meteorology)_. (R. DE C. W.)

CLIMATE IN THE TREATMENT OF DISEASE.--The most important qualities of the atmosphere in relation to health are (i.) the chemical composition, (ii.) the solids floating in it, (iii.) the mean and extreme temperatures, (iv.) the degree of humidity, (v.) the diathermancy, (vi.) the intensity of light, (vii.) the electrical conditions, (viii.) the density and pressure, and (ix.) the prevailing winds. Generally speaking, the relative purity of the air--i.e. absence of septic solid particles--is an important consideration; while cold acts as a stimulant and tonic, increasing the amount of carbon dioxide exhaled in the twenty-four hours. Different individuals, however, react both to heat and cold very differently. At health resorts, where the temperature may vary between 55° and 70° F., strong individuals gradually lose strength and begin to suffer from various degrees of lassitude; whereas a delicate person under the same conditions gains vigour both of mind and body, puts on weight, and is less liable to disease. And a corresponding intensity of cold acts in the reverse manner in each case. Thus a health resort with a moderate degree of heat is very valuable for delicate or elderly people, and those who are temporarily weakened by illness. Cold, however, when combined with wind and damp must be specially avoided by the aged, the delicate, and those prone to gouty and rheumatic affections. The moisture of the atmosphere controls the distribution of warmth on the earth, and is closely bound up with the prevailing winds, temperature, light and pressure. In dry air the evaporation from both skin and lungs is increased, especially if the sunshine be plentiful and the altitude high. In warm moist air strength is lost and there is a distinct tendency to intestinal troubles. In moist cold air perspiration is checked, and rheumatic and joint affections are very common. The main differences between mountain air and that of the plains depend on the former being more rarefied, colder, of a lower absolute humidity, and offering less resistance to the sun's rays. As the altitude is raised, circulation and respiration are quickened, probably as an effort on the part of the organism to compensate for the diminished supply of oxygen, and somewhat more gradually the number of red blood corpuscles increases, this increase persisting for a considerable time after a return to lower ground. In addition to these changes there is a distinct tendency to diminished proteid metabolism, resulting in an increase of weight owing to the storage of proteid in the tissues. Thus children and young people whose development is not yet complete are especially likely to benefit by the impetus given to growth and the blood-forming organs, and the therapeutic value in their case rarely fails. For older people, however, the benefit depends on whether their organs of circulation and respiration are sufficiently vigorous to respond to the increased demands on them. For anaemia, pulmonary tuberculosis, pleural thickening, deficient expansion of the lungs, neurasthenia, and the debility following fevers and malaria, mountain air is invaluable. But where there is valvular disease of the heart, or rapidly advancing disease of the lungs, it is to be avoided. Light, especially direct sunlight, is of primary importance, the lack of it tending to depression and dyspeptic troubles. Probably its germicidal power accounts for the aseptic character of the air of the Alps, the desert and other places.

Sir Hermann Weber has defined a "good" climate as that in which all the organs and tissues of the body are kept evenly at work in alternation with rest. Thus a climate with constant moderate variations in its principal factors is the best for the maintenance of health. But the best climate for an invalid depends on the particular weakness from which he may suffer. Pulmonary tuberculosis stands first in the importance of the effects of climate. The continuous supply of pure fresh air is the main desideratum, a cool climate being greatly superior to a tropical one. Exposure to strong winds is harmful, since it increases the tendency to cough and thus leads to loss of body temperature, which is in its turn made up at the expense of increased metabolism. A high altitude, from the purity and stimulating properties of the air, is of value to many mild or very early cases, but where the disease is extensive, where the heart is irritable, or where there is any tendency to insomnia, high altitudes are contra-indicated, and no such patient should be sent higher than some 1500 ft. Where the disease is of long standing, with much expectoration, or accompanied by albuminuria, the patient appears to do best in a humid atmosphere but little above the sea-level. The climate of Egypt is especially suitable for cases complicated with bronchitis or bronchiectasis, but is contra-indicated where there is attendant diarrhoea. Madeira and the Canaries are useful when emphysema is present or where there is much irritability of constitution. Bronchitis in young people is best treated by high altitudes, but in older patients by a moist mild climate, except where much expectoration is present.

The influence of atmospheric conditions on the functions of the nose is very marked. Within the ordinary ranges of humidity and temperature the nasal mucous membrane completely saturates the air with aqueous vapour before it reaches the pharynx. In cold and dry mountain climates there is a very free nasal secretion, far beyond what is needed for the saturation of the air; and at low levels the reverse action takes place, the nose becoming "stuffy." The mechanism on which this depends is found in the erectile tissue, and anything favouring the engorgement of the veins, such as weak heart action, chronic bronchitis or kidney troubles, &c, leads to a corresponding turgidity of the nose and sinuses. In addition to barometric and other influences, it has been found that light produces collapse of this tissue, smoke having a similar effect. On this latter effect probably depends the fact that many asthmatics are better in a city like London than elsewhere, the smoke relieving the turgescence of the inferior turbinals of the nose. In the treatment of pathological nasal conditions, all cases of obstruction from whatsoever cause are best in a dry atmosphere, and where there is atrophy and a deficient flow of mucus in a moist atmosphere. If the mucous membrane is irritable a dry sheltered spot on a sandy soil and in the neighbourhood of pine trees is by far the best.

Scrofulous children, namely, those in whom the resistance to micro-organisms and their products is low, pre-eminently require sea air, and had better be educated at some seaside place. Where the child is very delicate, with small power of reaction, the winter should be passed on some mild coast resort. Gouty and rheumatic affections require a dry soil and warm dry climate, cold and moist winds being especially injurious.

For heart affections high altitudes are to be avoided, though some physicians make an exception of mitral cases where the compensation is good. Moderate elevations of 500 to 1500 ft. are preferable to the sea-level.

In diseases of the kidneys, a warm dry climate, by stimulating the action of the skin, lessens the work to be done by these organs, and thus is the most beneficial. Extremes of heat and cold and elevated regions are all to be avoided.

FOOTNOTES:

[1] A. Supan, _Grundzüge der physischen Erdkunde_ (Leipzig, 1896), 88-89. Also _Atlas of Meteorology_, Pl. 1.

[2] W.M. Davis, _Elementary Meteorology_ (Boston, 1894), pp. 334-335.

[3] A. Supan, _Grundzüge der physischen Erdkunde_ (3rd ed., Leipzig, 1903), pp. 211-214. Also _Atlas of Meteorology_, Pl. 1.

[4] Approximately Lisbon has 28.60 in.; Madrid, 16.50; Algiers, 28.15; Nice, 33.00; Rome, 29.90; Ragusa, 63.90.

[5] i.e. lines drawn on a map to connect all places having an equal rainfall.

[6] _Nature_, lxxi. (Jan. 5, 1905), p. 221.

CLIMAX, JOHN (c. 525-600 A.D.), ascetic and mystic, also called Scholasticus and Sinaïtes. After having spent forty years in a cave at the foot of mount Sinai, he became abbot of the monastery. His life has been written by Daniel, a monk belonging to the monastery of Raithu, on the Red Sea. He derives his name Climax (or Climacus) from his work of the same name ([Greek: Klimax tou Paradeisou], ladder to Paradise), in thirty sections, corresponding to the thirty years of the life of Christ. It is written in a simple and popular style. The first part treats of the vices that hinder the attainment of holiness, the second of the virtues of a Christian.

EDITIONS.--J. P. Migne, _Patrologia graeca_, lxxxviii. (including the biography by Daniel); S. Eremites (Constantinople, 1883); see also C. Krumbacher, _Geschichte der byzantinischen Litteratur_ (1897); Gass-Krüger in Herzog-Hauck, _Realencyklopädie für protestantische Theologie_, Bd. 9 (1901). The _Ladder_ has been translated into several foreign languages--into English by Father Robert, Mount St Bernard's Abbey, Leicestershire (1856).

CLIMBING[1] FERN, the botanical genus _Lygodium_, with about twenty species, chiefly in the warmer parts of the Old World, of interest from its climbing habit. The plants have a creeping stem, on the upper face of which is borne a row of leaves. Each leaf has a slender stem-like axis, which twines round a support and bears leaflets at intervals; it goes on growing indefinitely. It is a favourite warm greenhouse plant.

FOOTNOTE:

[1] The word "climb" (O.E. _climban_), meaning strictly to ascend (or similarly descend) by progressive self-impulsion, with some apparent degree of laborious effort and by means of contact with the surface traversed, is connected with the same root as in "cleave" and "cling." For Alpine climbing, &c., see MOUNTAINEERING.

CLINCHANT, JUSTIN (1820-1881), French soldier, entered the army from St Cyr in 1841. From 1847 to 1852 he was employed in the Algerian campaigns, and in 1854 and 1855 in the Crimea. At the assault on the Malakoff (Sept. 8th, 1855) he greatly distinguished himself at the head of a battalion. During the 1859 campaign he won promotion to the rank of lieut.-colonel, and as a colonel he served in the Mexican War. He was made general of brigade in 1866, and led a brigade of the Army of the Rhine in 1870. His troops were amongst those shut up in Metz, and he passed into captivity, but soon escaped. The government of national defence made him general of division and put him at the head of the 20th corps of the Army of the East. He was under Bourbaki during the campaign of the Jura, and when Bourbaki attempted to commit suicide he succeeded to the command (Jan. 23rd, 1871), only to be driven with 84,000 men over the Swiss frontier at Pontarlier. In 1871 Clinchant commanded the 5th corps operating against the Commune. He was military governor of Paris when he died in 1881.

CLINIC; CLINICAL (Gr. [Greek: klinê], a bed), an adjective strictly connoting association with the bedside, and so used in ecclesiology of baptism of the sick or dying, but more particularly in medicine to characterize its aspect as associated with practice on the living patient. Thus clinical experience is opposed to what is learnt from laboratory research or theoretical considerations. The substantive "clinic" is technically employed for a medical school or class where instruction is given in practical work as illustrated by the examination and treatment of actual cases of disease.

CLINKER. (1) (From an old Dutch word _klinkaerd_, from _klinken_, to ring), a hard paving brick, a brick with a vitrified surface, or a fused mass of brick; also the incombustible residue of coal, which occurs, half-fused into hard masses, in grates or furnaces; a fused mass of lava. (2) (From _clinch_, or _clench_, a common Teutonic word, meaning "to fasten together"), a term appearing usually in the form "clinker-built" as opposed to "cravel-built," for a boat whose strakes overlap and are not fastened "flush."