The meteorological situations as indicated by charted observational data are not as definite in their indications of future weather conditions at some times as at others. The forecaster is, therefore, in the best position to place an estimate on the accuracy of his forecast and should transmit this estimate of accuracy with the forecast. It was a rule in the A. E. F. that unless odds in favor of the forecast were at least 3 to 1, the forecaster would issue a better forecast just as soon as conditions warranted.

An accuracy for the month of October 1918, of between 5 and 6 to 1 in the forecasts was found to check almost exactly with the forecaster's estimates of his forecasts for the month.

Meteorological information and forecasts should be issued with reference to the activity served and since they are for use by non-meteorologists, they should contain the essential element of decision, so far as meteorological conditions are concerned, that the meteorologist is, or should be, best qualified to supply.

Returning now to the network of airways that is rapidly coming into being over our country, we find them radiating from the great centers of population that have grown up around business, industrial, commercial, agricultural, or other activities. The center of operations of the American Forces on the western front in France is comparable to any one of these centers of civil activity, both as to aviation and other pursuits, and the meteorological system that served so well overseas is recommended as the ideal one for the effective and economical service of these centers. Three essential elements enter into this system. The first of these is personnel. While boys with high school education may be trained to make fairly reliable meteorological observations, it is essential that the meteorologist attempting to make a useful local forecast have thorough preparation in the physics involved in the weather processes. His preparatory work in physics should include thoroughly practical courses covering thermodynamics, kinetic theory of gases, neucleation, electron

theory and certain phases of spectroscopy. These studies should be carried well beyond the work usually prescribed for undergraduate students. The progress of personnel coming into the meteorological service with less preparation than this is seriously limited. Their experience as observers would, however, be an extremely valuable asset, if the more promising of them could be furloughed or in some way provided with the opportunity of completing the preparation in physics above outlined.

The second essential element entering into this meteorological system is a suitable number and distribution of observation stations so that every meteorologically distinct area of the country will have its station. The frequency and hours of observations at these stations should be such as to take care of the larger weather changes with provision for special observational reports as local conditions demand. Ideal hours from the point of view of our own country based on the 75th meridian, are 4, 10, 16 and 22, on the 24-hour dial.

The third essential element is the organization of these stations into suitable nets with communication facilities for the purpose of collecting the weather data observed. These nets should include:

(a) A country-wide net for the collection of regular observations. These regular observations once collected could, in whole or in part, be suitably distributed to centers of aviation and other activities and, properly interpreted there, would provide meteorologists in charge with essential information concerning the general weather conditions prevailing to the weatherward of the center served by them.

(b) Local nets about the various centers served for the collection of special reports required by the location and by the activities of the centers. These local nets will often overlap and it will frequently happen that an observation. station will report into more than one local net.

As between a general and a local forecast, that is a forecast applicable to a large area and a forecast applicable to a small

area, the latter is much the more difficult to make. It is proportionally the more useful, since it supplies information in greater detail and with greater definiteness. It follows that the key men of this ideal meteorological system will be located at the centers of flying and other activities, for which the meteorological service is provided. It will be the duty of each of these key men to become familiar with the activities of his center requiring meteorological service and to provide service with reference to these activities.

THE DEVELOPMENT OF THE HEAVIER-THAN-AIR

MACHINE

By C. H. BIDDLECOMBE

Formerly Major in the Royal Air Force

(Read April 20, 1928)

THAT phase of Aëronautics which is possibly the most interesting and certainly the most valuable to humanity is the creation of the commercial fleets of the air. From the day that the first voyager set out for the unknown-possibly by accident-astride a floating tree trunk, transportation has been the indispensable forerunner of civilization. On a continent where the civilizing influences of even the crudest forms of transport-canoes, horses and dogs are still exercised in reclaiming the hinterlands of Canada and South America, the airplane as a vehicle of commerce has, I believe, an arresting interest for the philosophic mind. The history of this newest agent of the God of Speed-the wing-footed Mercury-is extremely brief insofar as practical use is concerned, but, in the legendary song and story of the human race, winged flight has provided a theme for the poets of twenty-five centuries.

The earliest surviving myth is, of course, the story of Daedalus and Icarus, who may be said to have been the earliest proponents of the ornithopter—a wing-flapping type of airplane. The ornithopter was very naturally the first type of aërial vehicle to engage the thought of mankind, and for many centuries the flapping of wings seemed to be the logical means of obtaining flight. The earliest mention of a wing-flapping model which carried a suggestion of authenticity is the story related by Aulus Gellius, the Roman author of "Attic Nights," who refers to the flying dove of Archytas in terms that indicate successful short flights by a wooden model of a bird. A previous mention of attempted wing

flapping flight is the British legend of King Bladud, supposedly the tenth king of Great Britain, who died in 852 B.C. The story runs that Bladud made feather wings for himself and practiced gliding from high places; his enthusiasm presumably outstripped his skill one day, as he fell in flight onto the temple of his God Appolyn in the City of Trinoraitein-more widely known as London. Incidentally, King Bladud was the father of the equally mythical King Lear, and I sometimes wonder if Shakespeare had this in mind when he gave us King Lear as a madman.

The next outstanding figure in the legend of flight is Oliver of Malmesbury who flourished about 1020 A.D.; he is reported to have fitted wings to his hands and feet and jumped from a high tower, maintaining flight for about one eighth of a mile, when a gust of wind caused him to crash. Milton remarks of Oliver of Malmesbury that, "He got so conceited of his art that he attributed the cause of his fall solely to want of a tail, as birds have, and which he forgot to make to his hinder parts." Later on John Damian, a favorite courtier of James IV of Scotland, attempted a similar feat from the tower of Stirling Castle, and fell into the kitchen midden; a contemporary writer and critic remarked of this flight that hens' feathers would naturally return to the manure heap, so why did not Damian use eagles' wings?"

The legends of Greece and Rome, of India and China, the Sagas of Scandinavia-all have their quota of tales of flight by man, and the urge to conquer the Empire of the Air has been confined to no one period of human history, but it has been left to this present era of science and invention to realize the dreams of some thousands of years.

Passing over the notes on the mechanics of flight left us by Roger Bacon in 1250, the extremely interesting experiments of Leonardo da Vinci in 1450 and the balloon flights made in the eighteenth century, we come to the birth of the heavier-than-air machine in the first years of the nineteenth century.