the year. A study of such types in previous years showed the prevailing tendency was for a break up not to occur for a fortnight after such a High became established. This forecast made upon reasonably secure grounds, was correct for the larger part of the area.-G. F. H. Abstr. from Met. Mag., July, 1922.

A REVIEW

CLIMATIC CHANGES, THEIR NATURE AND CAUSES. By ELLSWORTH HUNTINGTON AND STEPHEN SARGENT VISHER (Large 8vo. xiii and 329 pages with 23 charts and tables.

Yale Univer

sity Press, New Haven and New York, 1922. $3.50) The first chapter in this very original and interesting work points out the wonderful uniformity of climate throughout all geological time, in the sense that the mean temperature of the earth, for at least several hundred million years has, according to the geological evidence, never varied more than perhaps 30° C. above or below the present level. Even this range of 60° C. (108° F.) may be double or triple the range that has actually occurred. That the temperature has not passed beyond certain narrow limits, whatever their exact degree, is clear from the fact that, if it had done so, all the higher forms of life would have been destroyed. The temperatures between 0° C. and 40° C. are shown to be extremely critical ones. Water which is essential for life becomes a solid below 0° C. and above 40° C. protoplasmic life is carried on with increasing difficulty and is rendered impossible at some point between 50° C. and 100° C. when water disappears and becomes a vapor.

In Chapter II, it is shown that, within the limits outlined in Chapter I, there has been great variability and the remainder of the book is devoted to explaining the character and probable causes of these variations. The variations associated with the eleven-year sunspot period, with the 35-year Brückner period, with historic climatic pulsations and with the glacial epochs all seem to be essentially of the same nature.

Chapter III considers the various hypotheses which have been advanced to explain climatic fluctuations of long period and especially of the hypotheses as to the cause of the glacial epochs. These have been very numerous. The best known appear to be, (1) Croll's theory of the changing eccentricity of the earth's orbit; (2) The carbon dioxide theory elaborated by Chamberlin, Arrhenius and others; (3) Changes in the form of the land surfaces of the globe, both as regards elevation into mountain chains and the greater or lesser extent of continental masses, a theory to which C. E. P. Brooks has recently devoted much thought; (4) The volcanic dust hypothesis originated by Abbot and Fowle and elaborated by Humphreys; (5) The hypothesis of polar wandering; (6) The thermal solar hypothesis.

This latter hypothesis assumes that all changes of climate, including the glacial epochs, are due to changes in the radiant energy coming from the sun. The authors adopt and develop this latter hypothesis. They believe that changes in solar energy have been the chief causes of climatic changes, but that the effects are modified by all the causes previously cited. One of the curious anomalies of solar activity, however, is that as the sun gets hotter the earth gets colder and glacial epochs are brought

about by intense solar activity. Chapter IV is devoted to explaining the influence of solar activity in increasing the number and changing the distribution of cyclonic storms. Chapters V and VI take up the pulsations of climate within historic times and Chapters VII and VIII are devoted to the glacial epochs.

In Chapters XI and XII there is a consideration of the terrestrial causes of climatic changes.

Chapter XIV takes up the question of the causes of solar changes and the authors incline to the view that these are external to the sun and probably arise from some kind of effect induced by the planets and by passing stars. They believe that the effect is brought about, not by means of gravity, but by some form of radiation from these bodies, possibly of the nature of electrons.

Schlesinger and his assistants made an elaborate computation of the movements of the nearest fixed stars in relation to the sun for the past 70,000 years and for the coming 70,000. A very interesting result of the comparison was that a Centauri approached to within 3.2 light years of the sun about 28,000 years ago, a time which corresponds very closely to the time of the last glacial epoch. Also a period of about 81 years in solar activity is thought perhaps to be due to the orbital rotation of the two stars in a Centauri whose period is about that length.

In Chapter XIV an apparent relation is pointed out between earthquakes and solar activity; and, as earthquakes are accompanied by movements of the earth's crust, it follows that these also may to some extent be brought about by solar changes, probably as a result of changes in the distribution of atmospheric pressure.

The authors find it difficult to explain the causes of all the phenomena presented by means of the accepted and well established physical processes in the atmosphere and Huntington has developed an hypothesis of electrical action which it will be difficult to maintain. This is the weakest side of the book and should have been omitted until a stronger basis in experiment and observation are available. The writer is a believer in the predominant influence of solar changes in producing climatic changes but their explanation by well known physical processes are not exhausted. The introduction of little understood processes in their explanation does not strengthen, but weakens the arguments in favor of this relation.

However, the volume is a bold and interesting attempt to solve some of the riddles of the universe and it is announuced will soon be followed by a second volume treating more fully of the relations of the sun and earth.-H. Helm Clayton.

"RAINFALL" AREA TEN FEET SQUARE.

Do not blame meteorology for the ten foot square "rainfall" that has been heralded from Alexandria, Va. Entomology explains it. Protesting at the fanciful explanations and the mystery that has been thrown about this phenomenon, Dr. W. J. Humphreys, professor of meteorological physics of the U. S. Weather Bureau, declares that plant lice produce the supposed rain.

These insects are found on sycamore and other trees by the thousands. They are little brown mites, three-sixteenth to one-eighth of an inch long,

which suck the sap from the leaves and squirt it out of their bodies. This secretion is the liquid that falls and appears to be rain.

The spot in Alexandria does not deserve the fame that it has achieved, Dr. Humphreys holds, as there are dozens of trees in Washington that are producing the same kind of "rain." Several of these are located on Pennsylvania Avenue and are so plentiful with the sticky moisture that pedestrians avoid passing under their aphid-infected branches.

The liquid produced by plant lice is of a honey-dew consistency and stays on the pavement or ground much longer than would the same amount of rain water. It has been suggested that something of this sort made the famous manna of the Israelites in their flight through the wilderness from Egypt.

It is also declared absurd to explain the Alexandria "rain" as the exuding of moisture from a tree itself. Although there is a tree in South America which is said to do something of the kind, none of the trees of the Virginia city are of this species.

Rain seldom falls in a ground-wetting shower over an area of less than one square mile, although a few drops may fall over a much smaller area, says Dr. Humphreys. Even the falling of rain in one part of the District of Columbia and not in another is an extremely local condition. (Cf. Similar Case, Sept., 1921, BULLETIN, p. 113).-Science Service.

ANIMAL "FORECASTERS."

Animals by certain actions are said to indicate coming weather. Many ascribe this to some instinct on the part of animals which makes them better forecasters than men. Others see in these actions merely responses to present conditions (Cf. this BULLETIN, April, 1920, pp 39-40). Anyone observing actions of animals as a basis for predicting weather is merely doing in a crude way what the trained meteorologist does with his instruments. Thus, animals, plants, corn-fodder, and whatnot, as well as barometers, thermometers, and hygrometers indicate current conditions. The experienced person observes these and makes his forecast.-C. F. Brooks.

They say it's going to be a hard winter because the hairs are so long on the backs of caterpillars, but I hope to get up to the Boston meeting. -H. I. Baldwin.

CO-OPERATIVE OBSERVERS' DEPARTMENT.

For Weather Observers in the Americas

In Iowa the personnel of co-operative observers has undergone a great change in recent years and is now composed largely of persons who have only a transient or commercial interest in the subject rather than the more deeply scientific and "hobby" interest that characterized the co-operative observer of 10 years or more ago. In the five years I have had charge of this office the turnover in personnel is about two-thirds. This is probably due to the general unrest of the people resulting from the war and I believe that I can see signs of a return to the former spirit in the recent acquisitions to our co-operative observing force.

It seems to me that a discussion of some of the things that co-operative observers encounter in reading and caring for thermometers and the exposure of instruments might be interesting to them. For example; in

practice the co-operative observer finds that his maximum and minimum thermometers after being set nearly always disagree about one degree, the minimum of course being lower. This is almost universally true even though the laboratory correction cards furnished from Washington may show the instruments practically without correction or with the minimum having slight minus corrections. In many cases this discrepancy has lessened the confidence of the co-operative observers in the accuracy of temperature observations. In this connection caution could be included relative to keeping small detached portions of the alcohol column from lodging in the top end of the tube in minimum thermometers. Suggestions could also be made for the use of the maximum thermometer that is on the verge of being a “retreater." The suggestion I have offered frequently is to lower the bulb very slowly, for reading, to an angle not greater than 45 degrees-just enough to insure the mercury going down firmly to the constriction. A description of the effect of radiated and reflected heat from the east, south or west side of a large building upon thermometers in the "cotton region" shelter exposed near any of these sides, would be interesting. In changing the location of a co-operative observer's instruments, from one observer's residence to another, I have always insisted on having the shelter well removed from these influences. The effect of low bushes or fences and high trees or other objects upon the catch of rainfall, would be interesting. Also the elevation of the gage itself from near the ground to considerable elevation. I had the recent interesting suggestion, from one who ought to have known better, that his rain gage be located just outside a window so that he could conveniently reach out and make measurements during the progress of a storm.

The difference in temperatures taken in similarly situated shelters painted white, dilapidated or painted some other color, would be interesting.

The importance of a record of snow on the ground each evening for the purpose of determining general snow cover, should be interesting. The extremely low minimum temperature that frequently follows a deep cover of fresh snow is of much practical importance. Though I have not followed this far I have nearly always been able to trace such temperature to active radiation of recently fallen snow. This has been brought out strikingly at Charles City, Iowa, which has a reputation for freak temperatures. Co-operative observers' records in the vicinity show that the condition is not peculiar to Charles City but very common to the entire area. A faithful record of snow cover would assist considerably in a study of this sort. On numerous occasions I have made good use of the snow cover idea in forecasting minimum temperature for shippers of perishable produce.-Charles D. Reed, Meteorologist and Director, Des Moines, Iowa.

KEEP COOL AND SAVE FUEL.

The most obvious way to save fuel is not to use so much of it, and you should not. U. S. Public Health Service officials claim that most of our city homes are too hot and that the average healthy adult could get

along just as well or better with a house temperature two to ten degrees lower than that usually maintained.

Americans are not such hot-house plants as to require the 72 degrees or more heat frequently found in their offices and apartments. Sixtyeight degrees, it is claimed, is a good temperature for the living room, while it can be kept at 65 without discomfort or ill effect.

Cutting the heat down from 72 to 65 degrees represents a saving of almost a fifth of the fuel bill, Bureau of Mines experts estimate. Some physicians claim that winter coughs and colds are more often due to having the house too warm than of keeping it too cold. The lower temperature would represent a lower doctor's bill in many instances.

Much fuel is wasted in heating rooms not in use. This is especially true of bed-rooms, as health is promoted by sleeping in unheated rooms to which plenty of fresh air has access.

People in France and other European countries apparently enjoy health and comfort, without ever having a fire in their house of the proportions which the extravagant American thinks necessary to his wellbeing.-Science Service.

NOTES.

DR. ANTON DAVID UDDEN, instructor in physics in the University of Pennsylvania, during the last year McFadden fellow of the AmericanScandinavian Foundation, studying with Professor Bohr in the University of Copenhagen, died in San Antonio, Texas, on September 5, at the age of thirty-five years. He succumbed to a nervous breakdown which occurred at the close of his study in Europe. Dr. Udden will long be remembered by war-time Signal Corps Meteorologists as a center of cheer as well as of inventiveness. His article on the distribution of meteorological elements at various levels in cyclones and anticyclones has just been sent to the U. S. Weather Bureau for publication in the Monthly Weather Review.

The officers of three sections of the American Geophysical Union for the year ending June 30, 1923, are: Meteorology-E. H. Bowie, chairman; R. DeC. Ward, vice-chairman; A. J. Henry, secretary. Terrestrial Magnetism and Atmospheric Electricity-W. F. G. Swann, chairman; L. A. Bauer, vice-chairman; J. A. Fleming, secretary. Physical Oceanography-J. P. Ault, chairman; G. W. Littlehales, vice-chairman; W. Ě. Parker, secretary.

The Wings of the Wind.

Hentzen, a student at the Hanover Institute of Technology, in commenting upon his recent motionless flight of more than two hours is reported to have said:

A motionless flight of a longer duration than the one I made today is not a question of the machine, but of nerves. The flight was certainly strenuous. I had to watch out and keep a sharp eye on every roll of the ground in order to catch or exploit every air current. The fact that I was able to maintain my altitude steadily so long over Wasserkuppe [a mountain of the Rhoen range, 3115 feet high] without being forced to glide down is due to the fact that upward currents favorable to air sailing were distributed over the whole hill region. Meteorological training and a thorough knowledge of wind currents is certainly of first-line importance to the pilot of a motorless airplane; a good machine comes in the second line.