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While the velocity of flow of water in an open channel is greater the higher the stage and is greater in a rising than in a falling river, yet the movement of crest stages-not being dependent wholly upon the velocity of flow-appears to be more rapid at comparatively low stages when the water is well within the banks of the stream than when the banks are overstopped as at very high stages. The reasons are fairly obvious although local conditions and the tributary effect may be the dominating influence as at Cairo, Ill., where, at times, the balance between inflow and outflow is disturbed by the channel capacity below Cairo. Overflow of lowlands on the left bank opposite and immediately below Cairo at stages above 40 feet results in more or less retardation in the velocity of the outflow and crest stages on the Cairo gage may be due to that cause alone.

The average rate of flood flow in the upper Ohio is about 5 miles per hour and on the Mississippi below Cairo very close to 4 miles per hour, although crest stages move at a slower rate.-Author's synopsis.]

This paper is followed by a short one on Rules for forecasting the crest stages at Vicksburg, Miss., based upon the stages at Cairo, Ill., by H. W. Smith. Then there are abstracts concerning, Flood prevention in the Minnesota Valley, by A. F. Meyer, and on, The influence of forest areas in non-forested regions upon evaporation, soil moisture, and movement of ground water, by L. T. Bode, with discussion by R. E. Horton.

The section of the Review on "Notes, Abstracts, and Reviews," contains the following: Sir Joseph Norman Lockyer, astronomer and meteorologist [obituary], Dr. George C. Simpson succeeds Sir Napier Shaw as head of the Meteorological Office, The unification of the meteorological services of Britain, Meteorology at the British Association meeting at Cardiff, The spectrum and the theory of the green flash, A study of the residual ionization in a gas with reference to temperature effects, On the variations of the radioactivity of the springs of Bagnolesde-L'Orne and their relation to rainfall, Can we extend our annual temperature record back for 30,000 years? Seasonal deposition in aqueo-glacial sediments.

December, 1920.

(Issued March 8, 1921.)

The December issue of the Review contains 15 contributions and 18 notes, abstracts or reviews. The contributions and some of the abstracts are noted below:

Atmospheric environment and health. Leonard Hill. (Pp. 687-690.)

[The experience of open-air schools and sanatoria shows that life spent largely in the open benefits the health of those subject to catarrhs, those with overnervous temperament, those with heart weakness, etc. Nevertheless, Europeans and Americans, dwelling in the colder climates, endeavor to build draftless houses and to secure inside these, by artificial heating, a climate similar to that on a quiet, dry day in summer. The low cooling power of the warm stagnant air indoors depresses the metabolism to a low level.

Out of doors the skin is cooled (and dried by the wind) and water is evaporated from it-the wind freely ventilating the clothes. The air on the most calm and oppressive day out of doors is never as still as it is in a shut-up room. The skin is also warmed by the radiant energy of the sun. The wind and the sun affect the flow of water from lymph and blood through the skin, the wind cools the blood in one part, the sun warms it in another; the sun's rays of shorter wavelength act chemically on the white skin. Cool winds insure the removal of the body heat by convection, as well as by conduction and evaporation.

What matters to the skin and respiratory membrane is not the relative humidity, but the actual vapor-pressure of the air which comes in contact with it. Cold, saturated air is excessively dry when warmed up to body temperature, and takes 1 Prepared for the American Meteorological Society meeting at Chicago, but received too late for presentation.

up much moisture from the body; warm saturated air (or only even half-saturated) far less. (Excerpts.)]

Note in regard to the primary cause of colds. J. R. Weeks. (P. 690.)

It may be suggested in explanation of the observed greater prevalence of colds with cyclonic weather, that previous dry weather has made dust which the winds have carried from the streets to our nostrils and throats, causing mechanical irritation and bacterial implantation and growth.—Excerpt.]

Comparison of temperature and humidity during 1920 with the mean, and their relation to comfort, at Anaconda, Mont. Č. D. Demond. (Diagram). (P. 691.) [The author, who is the Weather Bureau coöperative observer at Anaconda, finds "a very logical relation between our temperature-humidity figures during this year's mild-weather season and the comfort of the season."]

Relation of malaria to temperature. Reprinted. (Pp. 691-692.)

[The author, Maj. Angus Macdonald, has examined English temperature records from 1763 to 1919 in conjunction with malaria prevalence, and estimated the probabilities of continuous endemicity of the disease or recurrence in the present. He says further: "Elevation of temperature does not occur in England with regularity and continuity necessary to maintain endemic malaria. When the necessary coincidence of carrier importation and high mean temperature occurs, both epidemic and endemic malaria may break out for a limited time in limited areas. Many other factors affect the disease, and the living conditions in England over 100 years ago may have been more favorable to its incidence, but the temperature factor is essential."]

All of the above group was reprinted as a separate.

The rate of ascent of pilot balloons. B. J. Sherry. (Fig.). (Pp. 692–694.) [In approaching this question the writer divides the factors that control the rate of ascent of pilot balloons into two classes: (1) Those that relate to the kind and purity of the gas used, also to the shape, free-lift, material and surface of the balloons, and (2) those that relate to the atmospheric conditions prevailing at the time of the ascension, with particular reference to temperature distribution and air movement. The air density, viscosity, etc., are considered only indirectly. Numerous experiments were made with pilot balloons. The author expresses his conviction, however, that "it is probable that no entirely satisfactory formula for the rate of ascent of pilot balloons will be produced." Corrections to the formula now in use, especially to provide for the usual effect of turbulence near the ground, are presented.]

Some recent papers on the rate of ascent of pilot balloons. W. R. Gregg. (Pp. 694–696). Abstract and discussion.

[After citing theories set forth by Van Bemmelen and by R. P. Batty, the reviewer states: "The results given by the authors of the papers thus briefly reviewed are really not contradictory at all. They all show that the rate of ascent is higher than the average when the air through which the balloons rise is in a state of turbulence. This turbulence may be due to unequal heating of adjacent masses of air, to topographic irregularities, to high wind speeds or to different wind directions or speeds, or both, of adjoining layers.]

A report on two pilot-balloon ascents made at Shoeburyness. N. K. Johnson. (P. 696.) (Review reprinted).

[The author points out the extreme caution required in interpreting the upperair data derived solely from the single-theodolite method. The two balloons here cited developed defects and ceased their uniform rate of ascent after reaching 25,000 or 30,000 feet. He therefore lays considerable emphasis on how much more may be learned of the atmosphere where the two-theodolite method is employed.]

Visibility of pilot balloons. M. K. Johnson. Abstract. (P. 696.)

Vertical current detected by comparing cloud motion with apparent speed of pilot balloon. Joseph Leshan. (Fig.) (Pp. 696-697.)

[The pilot balloon ascension made at Washington, D. C., on the afternoon of November 23, 1920, showed a rapid rise in velocity up to the 800-meter level, and an almost equally rapid decline thereafter to the 1,800-meter level, when the balloon entered a roll of stratocumulus cloud. The appearance of the clouds

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and a nephoscope observation made at that time seem to show that the balloon gained about 100 meters during the last minute of ascension over the assumed rate of ascent, and that the velocity during the last minute should be corrected from 6.2 to 13.3 meters per second.-Author's synopsis.

A contribution to the meteorology of the English channel. H. G. Grant. Abstract. (P. 697.)

[An attempt to analyze the barometric disturbances which give rise to the Channel weather, and the relation of the topography to the sudden changes which occur.]

Pilot-balloon work in Canada.1 J. Patterson. (P. 697.)

The making of upper-air pressure maps from observed wind velocities. C. L. Meisinger. (7 figs.) (Pp. 697–701.)

The weather factor in aeronautics. C. L. Meisinger. (5 figs.). (Pp. 701-708). Certain relative insolation values. W. J. Humphreys. (P. 708.)

[Correction of table on page 20 in Davis' Elementary Meteorology and on page 80 in Humphreys' Physics of the Air.]

Influence of exposure on temperature observations. F. D. Young. (3 figs.) (Pp. 709-711.)

[Although the daily temperature observations of the Weather Bureau are designed to indicate as nearly as possible the temperature of the free air surrounding the thermometers, it is not practicable to accomplish this exactly, on account of the influence of the character of the exposure of the thermometers on the readings. Both maximum and minimum temperatures are affected.

The fruit-region instrument shelter, designed to allow a freer circulation of air and lessen the disturbing effects of exposure, is described in this paper and compared with the cotton-region shelter in general use.

Data are given to show differences between current temperatures inside the region shelter and current readings of the dry bulb of the whirled psychrometer outside the shelter, at different locations and at different hours. After sundown radiation of heat from the roof and sides of the shelter reduces the temperature of the air in its interior below that of the outside air. Within certain limits, the stronger the radiation and the more quiescent the surrounding air, the greater will be the depression of the temperature inside the shelter below that outside. Minimum temperatures recorded in different portions of the foliage of two lemon trees did not differ materially from those recorded inside a fruit-region instrument shelter, located between the two trees, all the thermometers being at the same height above the ground.-Author's synopsis.]

Differences between the readings of sheltered and unsheltered thermometers in field work.2 H. J. Cox. (Pp. 711-712.)

The comparison of the indications of some house thermometers in winter. H. I. Baldwin. (Fig.). (Pp. 712-713.)

[See BULLETIN, Apr., 1920, p. 39.]

Temperature and relative humidity in cold-storage plants for eggs and candy. O. T. Lay. (Pp. 713-714.)

[An account of the writer's experience in an investigation of aqueous vapor in its relation to certain cold storage problems. Following are some of the points discussed.

1. The temperature should be kept low for eggs and moderate for most kinds of candy.

2. The relative humidity should be comparatively high for eggs and low for candy.

3. The sling psychrometer was found to be the most practicable method of finding the relative humidity in different parts of the storage rooms.

4. The demand for such work has steadily increased in Chicago.

5. The probability that there is a latent field for such specialized work in other commercial centers.-Author's synopsis.]

The distribution of climatological stations.2 C. J. Root.

(Pp. 714.)

A comparison of two types of evaporation pans.2 G. A. Loveland. (P. 715.)

1 See Feb., 1921, BULLETIN, p. 21.

See Mar., 1921, BULLETIN, pp. 38-39.

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The meteorology of the Temperate zone and the general atmospheric circulation. V. Bjerknes. 2 figs. Pages 1-3.

[The squall and steering lines of cyclones constitute, when considered together, a line of discontinuity north of which the air is characterized by low temperature, high visibility, dryness, and motion from east and north. South of the line the opposite of these characteristics is the rule. The line of discontinuity, which can be traced for great distances, and, if observations were available, could probably be traced around the entire Northern Hemisphere, has been called the polarfront line, and may be regarded as the meeting place of polar and equatorial air.

Loops occasionally form in this line, with the result that masses of warm or cold air are separated from the parent masses. These loops and their results are somewhat dependent upon the latitude of the polar-front line. Such cutting off of air masses represents the formation of HIGHS and LOWS.

The weather of the Northern Hemisphere is the result of the advance and recession of the polar-front line. When the warm air extends farther north than usual, there is a tendency for an accumulation of cold air north of the line. When the pressure from this accumulation becomes sufficiently great, the cold air breaks through and flows southward, causing a change of the type of weather. Thus, the polar-front line is of great importance in forecasting, and, as observations are extended around the earth, it may assist in long-range forecasting.—C. L. M.] The energy of cyclones. Pages 3-5.

[This paper is in reality a symposium of a running discussion that has been appearing in recent issues of Nature (London). It presents in concise form the present ideas of British meteorologists on the intricate subject of cyclonic energy. A few excerpts from Sir Napier Shaw's remarks may, perhaps, give the best idea of the scope of these discussions and conclusions:

"A cyclone is a more or less stable dynamical system which certainly travels, but changes as it travels. The second aspect is the variation of velocity of the wind with height in the general circulation and in the cyclonic area itself. The third, which is closely connected with the second, is the trajectory of convected air. This could be calculated if we knew the point from which it started and the variation with height of the current which carried it."

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"Consequently my view at the present time is that the energy of a cyclone is due originally to convection in a region with a suitable law of velocity with height; it is guarded at the top by the isothermal condition of the stratosphere, and on the sides by the balance of pressure and rotation. It is open to slow attack at the bottom on account of the friction of its winds with the surface, and unless its energy can be maintained by additional convection it must perish. I do not think that a traveling cyclone carries its supply of rain for long distances; it probably manufactures it out of the material on the lowest levels which it has to pass over. But it uses the energy so supplied first to form a secondary, and afterwards to absorb it or to be absorbed by it."]

Balloon racing-a game of practical meteorology. Ralph H. Upson. Pages 6-7.

[This paper presents a strong plea for much more use of the free-balloon as a valuable aid in the study of meteorology. The writer, who has had considerable experience in practical ballooning, calls attention to the great advantage in making meteorological observations aloft with delicate instruments in a craft entirely free from pitching, vibrations, noises, and wind, and of the first-hand knowledge acquired in handling a balloon whose control is completely dependent on coördination with existing weather conditions.

The highest art of ballooning, says the author, finds expression in the national and international races which are held annually. These commonly run anywhere from 400 to 1200 miles' distance, and extend over 18 to 60 consecutive hours.-H. L.]

Meteorological aspects of the international balloon race of 1920. C. G. Andrus. 2 figs. Pages 7-11.

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[Successful free ballooning depends on meteorology, and especially on the study of free-air conditions. The International Balloon Race from Birmingham, Ala., October 23, 1920, was the first occasion of its kind in this country where meteorological upper air and surface reports were made available to the pilots and where assistance was provided to guide them in the interpretation and use of the telegraphic reports which the Weather Bureau supplied from the eastern and central United States. It is clear that more extensive free-air observations are necessary. Advices and up-to-the-minute data were of unusual value in this race, owing to the complex atmospheric conditions, which demanded a cautious nicety of control by the aeronauts. Conditions were not unfavorable at the surface, and were nearly normal in the free air. An analysis of the cyclonic conditions has been made in terms of the Bjerknes hypothesis of stream lines, and the application of this method explains the peculiarities encountered by the balloonists.

Explicit forecasts were made for the race. These verified, and the winning teams were those who followed closely the course mapped out by the Weather Bureau. Not merely the horizontal currents of the atmosphere but also the thermal activity and the radiation, condensation and equilibrium values must be given due consideration in the modern aerial weather forecasts for-free ballooning. Likewise, efficiency on the part of the aeronauts demands that they make the greatest use and allowance for the weather factor. Aerial transport of every character will do well to study this weather factor in order to promote greater efficiency.-Author's synopsis.]

The application of Bjerknes lines to the development of secondary lows. C. G. Andrus. 4 figs. Pages 11-12.

[The application of the Bjerknes lines of wind convergence to the solution of the problems of trough development at the time of the National and International Balloon Races in September and October, 1920, afforded some useful conclusions concerning the principles of the Bjerknes hypothesis in secondary LowS. This study has been made purposely only in terms of the surface elements and the winds aloft. Irregularities in these conditions, can be traced to imminent development of a change in the cyclonic formation. A description of these irregularities both at the surface and aloft has been made in order to record some forecasting hints, which, while neither infallible nor complete, offer some aid in detecting the sudden development of secondary Lows in barometric troughs.Author's synopsis.]

Origin of some secondary cyclones on the middle Atlantic coast. C. F. Brooks. 4 figs. Pages 12-13.

[When a strong cyclone centered in the Middle West extends its influence to the Atlantic coast a small secondary low-pressure area is often formed just inland from the coast. The southerly wind readily establishes itself at the surface along the low, flat coast, and therefore brings about a rapid fall in pressure not only by blowing away the dense, cold air, but also by bringing much warmer air soon from over the Gulf Stream. Perhaps a hundred miles inland, on the other hand, the relative roughness of the land tends to retain the cold surface air for some time, while the southerly wind rides over it. Once the pressure along the coast has become lower than that inland, a secondary eyclone develops and survives for the short time till the relatively small volume of cold air becomes mixed with the warm and blown away.-Author's synopsis.]

Note on deep easterly winds over the Middle West on January 24, 25, and 26, 1921. L. T. Samuels. Fig. Pages 13-15.

[Kite flights and pilot balloon observations made in the north-central portion of the United States on January 24, 25, and 26, 1921, showed easterly winds persisting to heights of 3 kilometers or more. Easterly winds at these altitudes are rare in the United States during the winter season on account of the strong latitudinal temperature gradients usually existing. Pressure was generally high to the north of this region and low in the south, with a moderately steep surface temperature gradient extending from south to north. A large temperature inversion at Ellendale, however, caused the pressure to remain higher over this

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