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society has lost, for he was clear of mind and kind in thought. Yet, whatever the sadness of friend, or grief of nearest and dearest, this we know: We honor him most who from his life are most inspired to serve.-W. J. Humphreys.

A fine appreciation by Meisinger's close friend, W. R. Gregg, has been published in U. S. Air Services, July, 1924, pp. 35-36.

The Council of the American Meteorological Society sent to Mrs. C. LeRoy Meisinger, and Mr. and Mrs. J. B. Meisinger the following expression of sympathy:

The Council of the American Meteorological Society individually and as a group express their deepest sense of personal and scientific loss in the death of Dr. C. LeRoy Meisinger. For years no greater misfortune has befallen American Meteorology than this untimely termination of so promising a research career. In five years of free air investiga tion and the application of meteorology to aeronautics, Dr. Meisinger had become the acknowledged leader in American hypsometry and aeronautical meteorology. Realizing the great benefits to science to be gained from systematic observations of atmospheric conditions from a free balloon by a highly trained meteorologist, Dr. Meisinger courageously undertook this investigation. We honor the memory of him who gave up his young life in the pursuit of knowledge for the benefit of all.

Resolutions by the American Meteorological Society adopted June 26 at its Stanford University meeting, are published in the minutes on pp. 103-105, below. At that meeting the formation of a Meisinger Aerological Research Fund was approved.

Meisinger Aerological Research Fund

A brief statement, approved in substance by a majority of the Council, is as follows. A more detailed announcement can hardly be made till after the Council has met.

"The Council of the American Meteorological Society has approved the formation of, and will administer a Meisinger Aerological Research Fund, in memory Dr. C. LeRoy Meisinger, who recently lost his life in the prosecution of aerological research.

"The purpose of this fund shall be the promotion of aerological research, by awards of fellowships, scholarships, grants, prizes, or medals, to the end that the type of research in which Dr. Meisinger was en. gaged shall be encouraged. Meisinger lost his life in such research. By fostering the investigations to which he would have devoted himself the American Meteorological Society can help to carry on Dr. Meisinger's work.

"Mr. W. R. Gregg, Treasurer of the American Meteorological Society, Weather Bureau, Washington, D. C., will receive and acknowledge any contributions."

Bibliography of C. LeRoy Meisinger's Scientific Articles Balloon_race from Fort Omaha, Nebr., through thunderstorms. Mo. Weather Rev. Vol. 47, pp. 533-534. 1919.

Constant elevation free-balloon flights from Fort Omaha. Mo. Weather Rev. Vol. 47, pp. 535-538. 1919.

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Free balloon flight in the northeast quadrant of an intense cyclone. Mo. Weather Rev. Vol. 47, 231-233. 1919.

Precipitation of sleet and the formation of glaze in the eastern United States, Jan. 20-25, 1920, with remarks on forecasting. Mo. Weather Rev. Vol. 48, pp. 73-80. 1920.

Preliminary steps in the making of free-air pressure and wind charts. Mo. Weather Rev. Vol. 48, pp. 251-263. 1920.

Climatological factors governing the selection of air routes and flying fields. Mo. Weather Rev. Vol. 48, pp. 525-527. 1920.

Effect of barometric pressure upon altimeter readings. Mo. Weather Rev. Vol. 48, p. 529. 1920.

Progress in making free-air pressure and wind charts. Rev. Vol. 49, pp. 238-239. 1921.

Mo. Weather

The preparation and significance of free-air pressure maps for the central and eastern United States. Mo. Weather Rev. Supp. No. 21. W. B. No. 784. 1922. (Abstract in Mo. Weather Rev. Vol. 50, pp. 453468. 1922.)

The pressure distribution at various levels during the passage of a cyclone across the plateau region of the United States. Mo. Weather Rev. Vol. 50, pp. 347-356. 1922.

Concerning the accuracy of free-air pressure maps. Mo. Weather Rev. Vol. 51, pp. 188-190. 1923.

The law of pressure ratios and its application to the charting of isobars in the lower levels of the troposphere. Mo. Weather Rev. Vol. 51, pp. 437-448. 1923.

The balloon project and what we hope to accomplish. Mo. Weather Rev. Vol. 52, pp. 27-29. 1924.

Interpretation of meteorological maps. Aviation, December 11, 1922, pp. 774-776.

Meteorology and balloon racing. Science, May 6, 1921, pp. 442-444. Notes on the early history of barometry. Tycos-Rochester, October, 1923, pp. 11-13.

The scope of aeronautical meteorology. Aeronautical Digest, April, 1923, pp. 251-252, 295.

Aviation and winds of the upper air. U. S. Air Service, April, 1921, p. 37.

The aviator and the meteorologist. U. S. Air Service, May, 1923, pp. 31-32.

Free-air wind charts for aviators. U. S. Air Service, July, 1923, pp. 34-39.

The thunderstorm and the aviator. U. S. Air Services, January, 1924, pp. 11-15.

The determination of free-air winds from surface weather conditions. U. S. Air Services, May, 1924, pp. 41-44.

In addition to the above, many notes will be found in Science and the BULLETIN of the American Meteorological Society.

OFFICIAL AIRPLANE ALTITUDE RECORDS

Notes on Lt. Macready's Flight

The following letter was addressed to the Secretary:

1. In the BULLETIN of April, 1924, page 61, the following statement is made: "Aside from the direct effects of the cold, the low temperature probably resulted in an unusually low pressure at the height of 34,983 feet reached. The fact of an altimeter reading 41,000 feet shows this." The fact is, however, this:

(1) The 41,000 feet was the isothermal altitude as indicated by a pressure actuated altimeter which was calibrated according to the formula

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where H is the altitude in feet and P is the atmospheric pres sure in inches of mercury.

(2) The 34,983 was taken from the barograph record which is also a pressure actuated instrument but was computed according to the formula of the Federation Aeronautique Internationale which is

(3)

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in which H is the altitude in meters (afterward converted into feet) and P is the atmospheric pressure in millimeters of mer

cury.

The pressure indications of both instruments were the same, but the formulae used to convert to altitude was different.

2. The BULLETIN also states: "Winter, especially cold winter weather when the pressure is not high at the ground, is, thus, not a favorable time to break altitude records. Warm, summer weather, when the surface pressure is high, especially in late summer greatest air density far aloft, and, therefore, the best chance of breaking an altitude record."

offers the

The fact is, the coldest days in winter are most favorable for breaking altitude records for the following reasons:

(2)

(1) The F. A. I. altitude is computed from the pressure alone, therefore it is desirable to reach the lowest pressure possible. The performance of the airplane is limited almost entirely by the density, therefore the minimum density which it is possible to reach with a certain airplane with certain equipment is fixed. Since the density is equal to a constant times the pressure di vided by the temperature, and is fixed in a certain case, and it is necessary to reach that density when the pressure is lowest, the flight must be made when the temperature is the lowest at the high altitudes which is during February or the first part of March.

(3)

3. The fact that the lowest pressure at a certain density is attained when the temperature is lowest is easily visualized by comparing the data given in the January, 1920 Monthly Weather Review. For example, in January a relative density of 60 per cent is accompanied by a pres sure of 426.2 m.m. and the temperature is -18.4° C. while in July the pressure is 456.2 m.m. and the temperature -1.4° C.

For the Chief of Division:

A. C. FOULK,

Acting Chief, Equipment Section, Engineering Division, Air Service. McCook Field, Dayton, Ohio, April 30, 1924.

In replying, the Secretary remarked:

I am sorry to have fallen into error, though I must say it was a very natural one, in view of the use of the words "altitude" and "feet" in speaking of the heights attained. It strikes me that there is something radically wrong with the method for computing altitude now in use. No meteorologist would ever think of computing the altitude of a sounding balloon or of a free balloon without taking careful account of the temperature element involved.

I am sending your letter and a copy of mine to Dr. C. LeRoy Meisinger,
the chairman of our committee on Aeronautical Meteorology.
Dr. Meisinger's comment follows:

AIR SERVICE BALLOON AND AIRSHIP SCHOOL
Scott Field, Belleville, Illinois

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I have been very much interested in thinking over your note in the BULLETIN, and Mr. Foulk's reply concerning matters relative to Lieut. Macready's altitude flight, and I thank you for sending it. The following is the result of my cogitation, and I hope that it will be found satisfactory by both you and Mr. Foulk.

There are two questions at issue: (1) Are the equations employed at McCook Field for the determination of altitude from altimeter and barograph readings valid? (2) What is the most favorable time of year for making high altitude flights, and why? Let us consider these separately.

(1) The readings of the two instruments, the altimeter and the barograph must, of course, correspond to the pressure existing at the maximum altitude attained. But the indications of the two instruments are discordant by about 6000 feet because the formulae used in calibration and computation were different. There is no apparent reason why the indication of one more than the other should be accepted. The fact that the barograph computation is based upon the F. A. I. formula appears to be no convincing reason why that result should be accepted as representing the true altitude attained, although it may have the merit of satisfying the requirements of the F. A. I.

Yet, neither of these equations takes into account that most important factor-[the existing] temperature. There is no denying that at a given free air level, the pressure is relatively high when the mean temperature of the air column is high. This is shown by the Laplacian hypsometric equation the validity of which is unassailable.

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in which pz and Ps are pressures at the high level and the surface respectively; Z is the length of the reduction column; a the coefficient of gas expansion; and the mean temperature of the air column.

Thus, at some given high elevation, say 30,000 feet, the barometric pressure is higher in summer than in winter. This is also borne out in sounding balloon observations. An altimeter using the F. A. I. formula would, therefore, show a higher indication in winter than in summer at that level. But the altitude attained would be the same in both cases. It would seem, consequently, that any formulas intended to determine the altitude attained in these high flights which do not take into conEsideration the factor of temperature are seriously inadequate. If the Lieutenant is after only a low barometer reading, winter is undoubtedly the time to get it but if he is after altitude there are other sides to the question. And that brings us to the second question.

(2) Mr. Foulk's assertion that "the performance of the airplane is limited almost entirely by the density, therefore the minimum density which it is possible to reach with a certain airplane with certain equipment is fixed" forms an excellent starting point. The given airplane has a certain density "ceiling" (if the aviators will permit the expres sion). What that density ceiling is is a matter of aeronautical engi

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neering and not meteorology. The meteorological aspect is introduced when we ask: At what season does a certain density (the minimum at which a certain plane will function) lie at the highest elevation above the earth?

If we are striving for altitude the question would not be; as Mr. Foulk implies; At what season would this minimum density be found at the lowest pressure? What he says is true that lowest pressure at a certain density is found with low temperature, but this does not mean that the lowest pressure is at the highest possible elevation for that certain density.

It should not be forgotten that the seasonal variations of density are not very great at high elevations; indeed, at 8 km. above sea-level, density is constant at all times and places. A glance at the tables in Monthly Weather Review Supplement No. 20 will show this. Consider the density graph given on page 24: Suppose the limiting density for a given airplane is 0.35 kg. per cubic meter. When does this density occur at the highest elevation? The graph shows that if the plane is limited by density alone it could ascend half a kilometer (about 1600 feet) higher in summer than in winter. The vertical density gradient represents the result of a conflict between the pressure and temperature gradients. Below 8 km. in winter the densities are higher than in summer; at 8 km. they are the same; above, densities are higher in summer. The conclusion then would be that summer rather than winter would be the better time for the flight to gain a maximum altitude with an airplane.

This reasoning is different from that given in the BULLETIN. I think your argument there is a natural one, if one does not consider the limiting factor in airplane performance. However, the result of both lines of reasoning is the same. Since the density really changes so little, I doubt if, in practice, it would make much difference whether the flight were made in winter or in summer. But certainly summer is the more logical and reasonable season. Mr. Foulk's tenet that "it is desirable to reach the lowest pressure possible" because the F. A. I. altitude is computed from pressure alone, surely cannot be accepted as satisfactory in the matter of attaining high altitudes.

I hope these remarks will contribute a little toward the clarification of the problem.

Sincerely,

[C.] LEROY [MEISINGER].

On Dr. Meisinger's suggestion the whole discussion was submitted to Mr. W. R. Gregg, Chief of the Aerological Division, U. S. Weather Bureau, for comment. His remarks follow:

The F. A. I. Formula

Much confusion is caused in the public mind by the conflicting reports issued as to the altitude reached in record flights or in flights in which attempts are made to establish new records. The present case is a good example: Two altitudes are given; the press is likely to publish the higher in the headlines and the other one in the text. Readers of the same paper will remember one or the other, depending on whether they glance only at the headlines or read the entire article.

There is a more serious aspect to the matter than this, however. It would be bad enough if either value given were approximately correct, but the probabilities are that both figures are considerably in error. (Let no one be hoodwinked by the inference of extreme accuracy contained in the last two digits of 34,983)

The first formula given in Mr. Foulk's note,

29.90

H = 62900 log10

P

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