H.—34.

which are as compact as possible, yet simple and such as in themselves to suggest the phenomenon they represent. For example, distinction has to be made between drizzle, showers, steady rain, snow and rain, soft hail, hail, and snow, and the various intensities of these forms of precipitation. The codes and symbols must be capable of ready interpretation by the aviator, who has to pass quickly from one country to another, from plain country to mountainous, or over the sea, and through regions where different types of weather are prevailing. If chaos is to be avoided, therefore, there must be intense and detailed co-ordinating work on the part of the 0.M.1. Codes have been invented which consist of groups of five figures. In six five-figure groups of the international code it is possible to convey as much information as would require upwards of fifty words of plain language. One of the more urgent matters dealt with by the Conference was a demand from the Italian Air Ministry that the constitution of the 0.M.1, should be changed so as to give representation at the Conference a more official character and make its resolutions binding. The general feeling of directors, however, is that nothing is to be gained by attempting to force its resolutions on any country. The members of the Conference are already all Government officials and are sent by their Governments. A resolution is seldom passed unless an overwhelming majority is in favour of it, and most resolutions are unanimous. Any change to which an important, even if small, minority is opposed is usually dropped. The resolutions must appeal to Governments by their reasonableness, and the members of the Conference must, in general, be the best persons to advise their Governments on meteorological questions. Nevertheless, the force of some of the arguments adduced by the Italians was realized, and a Commission of six, of whom I was one, was set up to undertake a revision of the statutes of the 0.M.1. One result of this was that a special Commission for Aeronautical Meteorology was created and its constitution incorporated in the statutes of the 0.M.1. This Commission will arrange meetings with regional Aeronautical Commissions, the International Convention for Aerial Navigation, and other bodies controlling international aviation, and, in consultation with them, determine the practical details of meteorological services along particular air routes. It will also study the relations between meteorology and aviation from the scientific aspect. The principal feature of the meetings of the Commission for the Exploration of the Upper Air was the great development shown to have taken place in the design of the radio-sonde, an instrument which is carried to very great heights in the atmosphere by a rubber balloon, and which signals down the pressure and temperature of the air at different levels by radio. During the last few years the Eussians, Germans, and French have made great progress in increasing the accuracy and compactness of the sondes, while reducing the weight and cost. But the instrument with which the Conference was most impressed was that designed by Dr. Vaisala of the Finnish Services. Whereas a few years ago an ascent with a radio-sonde cost about £40, one can now be made for £10, and the results are more reliable. This is very important, beer use a knowledge of conditions in the upper air is a very great aid to the forecaster. At present aeroplanes have to be used very largely for getting this information. They are very expensive, and the radio-sonde should soon greatly reduce the cost, while at the same time making the results more readily available. Another interesting recent apparatus is one designed by the French for observing the wind in the upper air in cloudy weather or at night. In this case a balloon carries up a wireless transmitter, and its position is continuously located by direction-finding. This enables the upper winds to be calculated, and will be a great boon in bad weather. The President of the Polar Year Commission, who has to accumulate an enormous mass of meteorological data and make copies of it available to individual investigators, gave an interesting exhibition of the means he is using to copy and store records. A large amount of material can be placed together and photographed on standard cinema film. Both the original negatives and positive copies can be made very cheaply. A cinema projector of the " baby " pattern can be employed for showing the data when use is to be made of it. In this way a year's continuous registration of temperature, for instance, can be shown on a few films and a thick year-book full of tables condensed into a small roll. The Chairman of the Commission of Agricultural Meteorology, Professor W. Schmidt, of Vienna, has made a number of studies in microclimatology. In one of these a valley of the Alps was thoroughly explored and the variations of wind, temperature, sunshine, &c, over the whole area closely recorded. These studies enable the value of the land in various parts to be accurately assessed and help greatly in deciding what use it should be put to, what crops should be grown in each part, and so forth. Though it is not possible to make such detailed surveys everywhere, much could be learnt from isolated cases, and by the use of proper physical reasoning their results could be applied to other areas. Sir George Simpson felt that work of this character was rather outside the scope of the official meteorologist, but it is difficult to see who else could do it so satisfactorily. The speed of air traffic is now so great that those associated with its control will require to know the daily progress of machines on various routes. Postal authorities and business men generally will also be concerned. Since such delays as occur will be due mainly to adverse weather, a demand has arisen in Europe for information from along the air routes in practically all parts of the world. This demand is certain to grow. At the same time meteorologists wish to extend the area from which they receive reports, since it is found that conditions at a great distance may have an influence on the local weather. Tentative arrangements were, therefore, made for the issuing of weather reports covering the whole world for at least one time of day from a few powerful radio stations. If the plan matures Sydney, for example, would broadcast a comprehensive list of reports from Australia, New Zealand, and the surrounding areas which could be heard in Europe or any other part of the world. We in New Zealand should be able to receive reports from Africa and South America if required. It is possible that such reports may sometimes enable us to anticipate the prevalence of a certain type of weather for periods of considerable length.

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