bin hot, dry, dusty regions which in the tropics are generally regarded as the most healthy, except to those whose constitutions require a moist atmosphere. 2.-MEDICAL OPINION Medical opinion has gone far towards the general adoption of the conclusion that there is nothing in climate to prohibit the white man from settling in the tropics. 3.-IMPROVEMENTS BY PUBLIC SANITATION The trend of medical opinion to the view that there is no physiological reason why the white race should not inhabit the tropics may lead to a change similar to that regarding some localities in the temperate zones, which were formerly regarded as death-traps and are now popular health resorts. 4.-OLD-ESTABLISHED EUROPEAN SETTLEMENTS IN THE TROPICS Similar improvements are in progress elsewhere and explain why some white colonies have existed for long periods in the tropics without physical deterioration. Many cases of the decadence or extinction of ill-placed European colonies in the tropics are of course known, such as the Bahamas, as described by Professor Ellsworth Huntington. Such misfortunes have been regarded as evidence of the inevitably injurious effect of the tropical climate on white men. But if white colonies have maintained good health in the tropics, the failures are not caused by climate alone. 5. THE DEVELOPMENT OF TROPICAL AUSTRALIA The experience of colonization in tropical Australia is limited to about seventy years; but it affords no ground for the expectation that the ultimate effects on the white race will be detrimental. 6. RATE OF PROGRESS AND THE DRAWBACKS OF THE TROPICAL CLIMATE The results of the Australian decision in 1901 to discard coloured labour have shown that the daring policy then begun is practicable; but it may render development slow and costly. The slowness of the progress may be amply compensated by its sureness in the end. The The conclusion that white settlement of the tropics is possible should not lead to the drawbacks of a tropical climate being overlooked. conditions where the wet bulb temperatures are high are uncomfortable and unfavourable to mental and physical activity. People who are not keenly interested in their work should avoid the tropics. Ellsworth Huntington, in a valuable series of works, has called attention to many facts which show the dependence of Western civilization on the stimulating nature of the temperate climate, for the frequent changes in temperature and wind are conducive to alertness and general efficiency. The enervating effect of the tropical climate is no doubt counterbalanced by various compensations. Man needs less in food, fuel, clothing, and housing, while the same amount of exertion will produce a more #luxuriant and valuable crop. The supremely fertile tropical regions have, however, usually a hot muggy climate, which is not attractive to Europeans while areas with less trying conditions are available. 79 Northern Australia, even if it were not hampered by a high proportion 7. CONCLUSION The conclusion that the white man is not physiologically disqualified from manual labour in the tropics and may colonize any part of Australia simplifies inter-racial problems, as it provides an additional outlet and spacious home for the European race. The preceding survey of the position where the three main races meet in intimate association indicates that the world will have a happier and brighter future if it can avoid the co-residence in mass of members of the different primary divisions of mankind. Individual association and contact should secure for each race the benefit of the intellectual, artistic, and moral talents of the others; while industrial co-operation should aid each nation to make the best use of the land in its care. The world has reached its present position by the help of each of its three great races, and it still needs the special qualities of each of them. The contemplative Asiatic founded all the chief religions, the ethical basis of civilization. The artistic Negro probably gave the world the gift of iron, the material basis of civilization. The administrative genius of the European race has organized the brain power of the world to its most original and constructive efforts. The affectionate, emotional Negro, the docile, diligent Asiatic, and the inventive, enterprising European do not, however, work at their best when associated in mass. That association is attended with serious difficulties; for race amalgamation, which is the natural sequel, is abhorrent to many nations, and the intermarriage of widely different breeds, according to many authorities, produces inferior offspring. The policy of co-residence with racial integrity has failed to secure harmonious progress in North America and South Africa. The development of the best qualities of the three races requires their separate existence as a whole, with opportunuities for individual association and co-operation. In view of the inter-racial difficulties that have developed wherever the races are intermingled, Australia will throw away a unique oppor tunity if it fails to make a patient effort to secure the whole continent as the home of the white race. METEOROLOGY AND CLIMATOLOGY AT THE BRITS H ASSOCIA. meteorological and exchange ideas. At the sessions of Section A, sixteen Section E, M had one. the American Meteorological Society (see report p. 129 below), an informal conference in Sir Frederic Stupart's office addressed by Sir Napier Shaw, Dr. V. Bjerknes, and others, and a general meteorological luncheon. The meteorological luncheon, a usual feature of the British Association meetings, was on this occasion a notable gathering of about 80 directly or indirectly interested in meteorology and climatology. Sir Frederic Stupart, Director of the Canadian meteorological service was host. Sir Napier Shaw, dean of British meteorologists, acted as Master of Ceremonies, and brief remarks were made by Messrs. L. A. Bauer, V. Bjerknes, E. W. Brown, C. F. Marvin, J. J. Shaw, and others. Notes on the meteorological and climatological papers and discussions are presented below: MR. F. J. W. WHIPPLE-An Experiment Illustrating the Theory of the Green Flash. When the sun sets under favourable conditions the last glimpse appears a brilliant green. The theory that the phenomenon is due to the simultaneous action of dispersion and absorption is now generally accepted. The experiment is designed to illustrate this theory. SIR NAPIER SHAW, F.R.S.-If the Earth went Dry. The phenomena of the general circulation of the atmosphere depend fundamentally upon warming at the surface by the sun's rays and on cooling these by outward radiation; but the dominant factor of weather is the modification due to water-vapour in the air. In this paper, in order to clear ideas, the reader is invited to regard these two aspects of thermal influence as distinct, and to consider the effect of “dry heat" alone. We thus form an idea of what the general circulation would be if there were no water-vapour at all in the air. The subject is hypothetical, inasmuch as the actual circulation is generally affected by the condensation or evaporation of water, but its discussion is not necessarily sterile. It is an exercise in some important points of thermal economy; in deserts the conditions postulated are approximately realised, and yet winds, dust-storms, and "dust devils" are not infrequent there; and in the large part of the atmosphere where the temperature is below 270 t the relative amount of water-vapour, though not by any means without function, is too small to play the dominant rôle. It is assumed that "dry" air (except for dust) would be perfectly transparent. Radiation received by a perfect absorber normal to the sun's rays would be 135 kilowatts per square dekametre (subject to small variations of the solar constant), and the loss of heat from a surface radiating perfectly (subject to local variation on account of dust) would be .572 X (t/100) kw., and range from 9 kilowatts per (10 metre) 2 2 for 200 t to 46 for 300 t. A table is given of the temperatures (between 200 t and 402 t) at which the loss from a radiating surface would balance the income for given solar altitudes. The technical discussion is in five sections: 1. A survey of the thermal processes operative in the absence of water-vapour: (a) the katabatic effect of inclined surfaces cooling in the polar night; (b) the slow thermal convection, upward, by the build. ing up of layers of dry air in convective equilibrium over flat solarised surfaces (incidentally the question of superheated air is dealt with); and (c) the mixing of superposed layers by eddy-motion. 2. An estimate of the flow of air necessary to keep a steady state of temperature on a polar slope under assumed conditions during prolonged nocturnal radiation. A possible value of 300 km. per hour offers a justification for the use of the term "dust blizzard” as descriptive of the weather. 3. An estimate of 2 km. as the probable daily height of a layer in convective equilibrium under a tropical sun. 4. Diagrammatic sections of surfaces of equal temperature and of equal potential temperature for sunrise and sunset at solstice and equinox. A permanent stratosphere, nibbled daily by a convective troposphere, is presupposed for the purpose of estimating its probable temperature, which is near 300 t. The incidental curiosities of temperature are set out. 5. The pressure and winds consequent upon the temperature are sketched, with the conclusion that a polar front would still be operative and a general circulation not dissimilar in some of its main features from the present form. SIR FREDERIC STUPART-The Variableness of Canadian Winters. In normal seasons North Pacific cyclonic areas usually move southeastward, with their centres well off the coast until at about the latitude of Northern British Columbia they enter the continent, while anticyclonic conditions of moderate intensity with low temperature prevail in Yukon and the Mackenzie River. In certain years, however, the Pacific cyclonic areas are less intense and enter the continent further south, while great anticyclonic developments occur in the far north and sweep south-eastward over Canada, accompanied by severe cold waves, which not infrequently reach the Atlantic coast. These conditions lead to abnormally cold winters in Canada. In other years the North Pacific cyclonic areas appear to be of such intensity that they force their way into the continent in high latitudes and actually prevent the formation of anticyclones and their concomitant low temperature. These conditions lead to mild winters in Canada. The Meteorological Service is investigating as to whether there is any connection between the temperature and position of the Japan current and the behaviour of these cyclonic areas. PROF. J. C. MCLENNAN, F.R.S.-Recent Developments in Low Tem· perature Research. Several months ago, it was suggested by Dr. L. Vegard, a Norwegian physicist, that the highest levels of the atmosphere were composed largely of frozen nitrogen. He compared the spectrum of the aurora with that of frozen nitrogen electrically excited, and found them ap parently identical, as a green band in the frozen nitrogen covered the region of the principal green line of the aurora. Vegard felt safe in erecting an elaborate hypothesis on this close similarity. He postulated also that this high, rare, nitrogen frost cloud was in large part responsible for the blue color of the sky. This hypothesis, requiring such a low temperature for the auroral region, as against a moderately high one computed from meteor observations, was received incredulously. At the recent British Association meetings in Toronto, Prof. J. C. McLennan presented evidence on this question, showing that Vegard's hypothesis is apparently without foundation. A very careful study of the frozen nitrogen spectrum revealed that the green band Vegard had observed was made of three distinct green lines no one of which coincided with the principal line of the auroral spectrum. There is no reason, then, for believing that our atmosphere is frozen at a great elevation. We still do not know and have not even a good guess as to what makes that green line in the aurora's spectrum.-(Why the Weather? No. 423). M. A. GIBLETT, L. F. RICHARDSON, and F. J. W. WHIPPLE—Meteorological Observations while crossing the Atlantic from England. The group of British meteorologists while en route to the meeting had an excellent opportunity to observe meteorological conditions at sea, and to make some special series of observations. The first day out, M. A. GIBLETT, Forecaster, found on making the weather map that a Low was forming with an equatorial air current in its south quadrant 10 degrees F. warmer than the air in the other quadrants. A forecast of heavy rains for the south of England was verified. The daily weather maps made at sea from radio reports were good, though there had been no special preparations. On the crossing, the prevailing weather was the "eternal stratus" type, the cloudy weather attending eddying of the wind over the water. On steaming up the St. Lawrence, the formation of cumulus clouds over the land was striking. There were cumuli over Anticosti, clear skies beyond and then towering clouds over the mainland. The angular distance between the nearest and farthest cumuli over Anticosti led to a computation of 22 miles as the width of the island. The captain's chart showed 21.5 miles in the line of sight. MR. GIBLETT closed his remarks by emphasizing the importance of sea and air temperature measurements, and the need for further precautions in measuring air temperature at sea. MR. RICHARDSON's special study was of lapse rates for a small height over the water. For the purpose he used a resistance thermometer screened by a double aluminum tube kept pointed to the wind by a vane. A small string galvanometer indicated the temperatures after calibration with an Assmann aspiration psychrometer. To get temperatures at different heights the thermometer was hauled up and down from the yard-arm. Observations were made mostly at 28 and 44 m. above the sea. At the surface of the sea the air temperature was considered the same as that of the sea. Between 28 and 44 m. the lapse-rates were commonly adiabatic. Non-adiabatic, stable conditions occurred over small patches (100 km. across) of cooler water. MR. WHIPPLE criticized Mr. Richardson's diagrammatic assignment of equal lapse rates from the sea surface to a height of some meters. He said the temperature of the lower air may be the same as that of the water only up to 18 m. Mr. Whipple's special study was of temperatures on and about the bridge in comparison with the temperatures inside the screen. He found the daytime temperature about 2 |