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tures with the same concentrations in soil solutions.

3. "The toxicity of soluble salts in the soil was found to be in the following order: sodium chlorid, calcium chlorid, potassium chlorid, sodium nitrate, magnesium chlorid, potassium nitrate, magnesium nitrate, sodium carbonate, potassium carbonate, sodium sulfate, potassium sulfate, and magnesium sulfate."

Since the author did not determine and did not know how much of these salts were actually in the soil solution he could not very well indicate their relative toxicities. It will be noted that sodium carbonate is placed near the bottom of the list as a relatively harmless salt, whereas, as a matter of fact, it is one of the most toxic salts occurring in the alkali soils of the west.

4. "Land containing more than the following percentages of soluble salts are probably not suited without reclamation to produce ordinary crops: In loam, chlorids 0.3 per cent.; nitrates, 0.4 per cent.; carbonates, 0.5 per cent.; sulfates, above 1.0 per cent. In coarse sands, chlorids, 0.2 per cent.; nitrates, 0.3 per cent; carbonates, 0.3 per cent. and sulfates, 0.6 per cent."

Here again the author draws conclusions without having accurate data on which to base them. If the above percentages were to be adopted by chemists in determining the suitability of alkali soils in the field for crop growth, the results would be misleading in the extreme. The results are not in accord with those obtained by determining toxic limits in field studies, nor with laboratory experiments in which toxicity is related to the alkali actually in the soil solution instead of to that which was put in.

In the paper by Harris and Pittman, published in November, 1918, the authors have adopted the same erroneous method but they are more careful in drawing conclusions as the absorption of the salts added is apparently recognized but is not determined and related to crop growth. The conclusion, however, that "Loam soils and soils with a high waterholding capacity may be successfully farmed at a higher alkali content than others" may

possibly be true but there is no data given in the paper which justifies the conclusion, for the per cent, of alkali salts recoverable from the two kinds of soil was not correlated with crop growth.

It is also suggested that the results obtained by Brown and Hitchcock published under the title "The effects of alkali salts on nitrification" (Soil Science, Vol. IV., No. 3) and by Singh on the "Toxicity of alkali salts" (Soil Science, Vol. IV., No. 6) would have been more valuable had they been correlated with the recoverable salts rather than with the salts added to the soils with which they were working.

F. B. HEADLEY

NEWLANDS EXPERIMENT FARM, FALLON, NEVADA

ON HIGH-ALTITUDE RESEARCH

I AM beginning to appreciate the difficulty of making one's self understood in a statement where matters are suggested rather than explained in detail, and where a critical attitude is urged until a result is actually verified by experiment, even when one feels perfectly confident beforehand what the result will be. The present statement is written for the purpose of correcting any misconceptions that may have arisen from my recent press

statement.

First, the time necessary for a preliminary exploration of the atmosphere will be required chiefly for the preparation. It is not like an exploration of "darkest Africa," for, with the proper rocket apparatus and instruments, each flight will occupy but a short time; and not many will be needed to obtain a very considerable amount of information, such as an accurate knowledge of densities, that would be needed for any further developments.

The expense also will be chiefly that for preparation; namely, for machine construction and tests. A final form of apparatus, designed for reaching any particular altitude, should not be expensive. This is, of course, true of any product that requires machine development.

Incidentally, the object of these experiments is by no means restricted to the taking of photographs in the earth's atmosphere, although this application may have more uses than were at first suspected.

Regarding the ultimate developments of the method, I do not wish to leave the impression that these will be restricted to researches in or near the earth's atmosphere. On the contrary, every one of the matters so far proposed is, as I have already maintained, based upon sound physical principles, and can therefore be realized. Further, there are additional principles, the application of which is certain to lead to results of even greater interest and importance. All these results will be realized, however, not by argument and discussion, but by the application of real research methods to the problems that are waiting to be solved.

CLARK COLLEGE,

ROBERT H. GODDARD

WORCESTER, MASSACHUSETTS

SCIENTIFIC BOOKS

Studies on the Variation, Distribution, and Evolution of the Genus Partula. The Species Inhabiting Tahiti. By HENRY EDWARD CRAMPTON. 313 pp., 34 plates, 252 tables, 7 text figures. Publication No. 228 of the Carnegie Institution of Washington, January, 1917.

Interest having been diverted from pure science by the war, no adequate review has appeared of this monumental and fundamentally important work which represents the results of four journeys of exploration made by its author in Polynesia; in the course of which more than 75,000 adult snails were collected together with over 7,000 adolescent individuals; more than 200 of the valleys of the Society Islands having been visited for this purpose.

The present volume deals with snails from Tahiti alone, and the thorough, scholarly, and conservative treatment given the subject renders this work of paramount value to all future students of the variations of Partula. Not alone were variations and distribution

of the adult snails studied, but the young contained in the brood pouches of the adults were dissected out, thus throwing light upon the fecundity of each variety, and the ratio of elimination of the young before they can reach maturity.

Crampton shows that these snails are not found in the dry low-lands along the shore, nor do they occur in the cold regions of the high peaks of the interior, for a temperature of 55°-60° F., stops their activity. The snails are therefore restricted to the relatively moist deeply wooded troughs of the intermediate regions of the valleys where they are commonly found during the day-time on the undersides of the leaves of the banana, wild plantain, caladium, turmeric, wild ginger and dracæna.

The ridges between valleys are generally dry, and thus the snail population of each valley is more or less isolated. Crampton finds that these snails descend from the trees and bushes and feed during the night, or on moist days, upon decaying vegetation. The young and adolescent being more active in this feeding reaction than are the adults.

It has long been known from Garrett's studies that the Tahitian species of Partula like the Achatinella of Oahu varied from valley to valley, some forms ranging over a wide area while others are restricted to a single valley, or even to a limited region within a valley.

In general moreover the farther apart two valleys the wider the diversity between their snails, although this is not always the case. Crampton's work has the merit of giving precision to our hitherto more or less vague knowledge of the distribution of the 8 species of Partula found in Tahiti. He shows conclusively that great changes have occurred since Garrett studied the snails, in 1861-1884, and that in some cases the species have spread over wider areas, and in the interval have produced some new sub-species or varieties. Thus the fascinating picture of a race in active process of evolution is presented. The details of this process are rendered clear by the excellent photographs of relief maps, and

the numerous diagrams which accompany the

text.

In a brief review such as the present it is not possible to do justice even to some of the more important details of Crampton's masterly work, but it is interesting to see that according to Garrett, Partula clara was rare and found only in a sector of valleys comprising about 1/4 the area of Tahiti, while Crampton found it to be very common and to range over 4/5 of the whole island, this dispersal having been accomplished by migration from the former restricted habitat of the species. There are now 7 subspecies, and mutation has occurred not only in some of the new valleys the snail has occupied since Garrett's time but also in the area in which it was found by Garrett.

Partula nodosa which in 1861 was confined to Punaruu valley has now migrated into 6 other valleys, and 3 new varieties have arisen in the area into which it has traveled, as Crampton illustrates in his text-figure 6 on page III.

Nearly one half of Crampton's volume is devoted to an analysis of the group species Partula otaheitana with its 8 subspecies and varieties of primary, secondary, and tertiary degree, thus constituting the most complex of the known species of Partula.

Crampton collected more than 20,000 adult and 6,000 adolescent snails of this form in practically every habitable area of Tahiti.

In Fautaua valley these snails form an extremely complex colony which stands in parental relation to the diverse colonies of other valleys; for in any one of the latter the shells exhibit one combination or another of the so-called unit characters displayed by the Fautaua group as a whole. In this snail Crampton finds some evidence that in the variety rubescens red and yellow colorations bear a Mendelian relation to one another, red being dominant. On the other hand in the variety affinis plain color seems to be dominant over the banded pattern in Mendelian inheritance.

Partula hyalina is peculiar in not being confined to Tahiti for it is found also in Mangaia, and Moki of the Cook Group and

Rurutu and Tubuai of the Austral Islands, and in marked contrast to this wide dispersal Partula, filosa, is found only in Pirai, and P. producta in Faarahi valley and have not migrated from these valleys since Garrett's time.

Crampton concludes that in the production of new varieties the originative influence of environment seems to be little or nothing, and isolation is a mere condition and not a factor in the differentiation of new forms. This is in accord with the studies of Bartsch upon Cerion, for he found that no new varieties were produced in any of the numerous colonies of Bahama Cerions which he established upon the Florida Keys from Ragged Keys near Miami to Tortugas. When however, these Cerions of Bahaman ancestry crossed with the native Florida from the second generation of the hybrids gave rise to a large number of variations both in form and color.

This observation indicates that similar experiments should be conducted upon Partula, for it seems possible that new species may result from the breeding of mutations with the parent stock, or of species with species producing fertile hybrids unlike either of the parent stocks.

The editorial work upon Crampton's volume reflects the greatest credit upon Mr. William Barnum the well known editor of all publications of the Carnegie Institution of Washington. The 15 colored plates lithographed by Hoen are faithful reproductions of the colors and appearance of these snails, and the fact that the book is published upon the best of paper is fortunate for it will be even more interesting to students a hundred years hence than it is at present.

Crampton's work is of such wide interest and importance, and in the light of Bartsch's observations so suggestive of future experimental research that it is hoped these studies may be pursued continuously under the auspices of the Carnegie Institution until final conclusions have been reached through breeding experiments conducted in the field.

A. G. M.

GRAVITY AND AEROSTATIC PRESSURE ON FAST SHIPS AND AIRPLANES

THE latest issue of the Meteorological Office Circular, No. 42, December 1, 1919, contains an interesting note on the Behavior of Marine Barometers on board fast ships. The views expressed are based on certain experiments made by Professor Duffield upon the value of gravity at sea. In his work it became necessary to study carefully the variations of pressure recorded by a mercury barometer of the new type under different conditions of ship motion.

It has been suspected for a long time that on fast ships and in strong winds, pressure readings might be considerably influenced by eddy action.

The experiments in this case were carried out on H.M.S. Plucky, a destroyer. Steaming at 22 knots against a head wind of about 12 m/s., the barometer showed a fall of 1.2 kilobars compared with the reading when going with the wind. This is an aspiration effect and will vary with the location of the instrument aboard the ship. Three barometers were used and the change in the cabins was only 0.4 kb. The fall is sudden and unless the navigating officer is posted might be taken as an indication of impending change in weather. It is stated that opening or closing doors and ports did not materially affect the readings but this we are disposed to question since it has long been known that very noticeable aerostatic pressure variations occur during high winds on opening or shutting doors and windows. At Blue Hill Observatory using large and sensitive barographs with fast moving record sheets we have obtained variations of from 3 to 5 kbs. The location of the opening determines the character of the change; windward openings cause a rise, leeward ones, a fall.

This brings home the necessity of correcting the records of fast ships and it would be especially interesting if our Hydrographic Office would furnish open scale barographs to fast ships and analyze the variations in aerostatic pressure when such vessels were encountering high winds ahead or astern. If

our ships and planes could also carry pressure tube anemometers of the Dines's pattern or the modified form provided for the Navy, records showing to a nicety gustiness and relation of speed to pressure would be available.

The next interesting feature of these experiments is the deduction that a ship moving east and therefore travelling with the earth's rotation experiences a consequent increase in the centrifugal tendency, resulting in a slight decrease in the value of gravity as indicated by a mercurial barometer. A west-bound ship, on the other hand, would show an apparent increase. This was put to test on the Plucky and it was found that

on a west course the mercury barometer when compared with an aneroid stood relatively higher than when on an east course, indicating that the mercury weighs less because a longer column is needed to give the same pressure. For a speed of 22 knots the difference amounted to approximately 0.2 kb.

Since bodies travelling east are lighter than when they are travelling west, we expect to find (other things being equal) a west wind above an east wind, a shell fired east with a longer range than when fired west, and an airship going east with a larger carrying capacity than when flying west. H. M. S. Plucky weighed about 4 cwt. less on an east course than when steaming west. Professor Edward V. Huntington in SciENCE, January 9, 1920, p. 45, shows that a body moving westward at high speed requires an increase in the supporting force.

Dr. Carl Herring in the same issue discusses the possibility of moving a mass so rapidly that the net weight would be zero.

Aerographers of course are familiar with the equation on which the above reasoning for gravity rests, namely 20v cos & sin a. In this, is the angular velocity of the earth's rotation, that is 2"/86164 seconds or .00007292 radians per second; v, the velocity of the ship in meters per second, p, the latitude and a the deviation from true north or south, of the ship's course. Dr. Duffield gives this value for latitude 50° N. as .005 kb. per knot.

Another matter under discussion is the effect of the ship's vibration due to engines upon the sensitiveness of the barograph record. At present it can be said that on a vi

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must watch his barometer not less than his compass. With him it is all important that true static pressures be recorded; and at least he should be keenly alive to the importance of the corrections to be applied, most of them functions of speed. When an aneroid is moving at 45 m/s (100 miles an hour) not an unusual speed, he may be called upon to add to or subtract from his proper speed, the air speed, say 25 m/s., also the earths angular velocity.

The exposure of the barograph is important. The containing box must have an opening either facing the wind or away from it: if the former, the pressure shown is aerostatic plus aerodynamic. Zahm and others have discussed pressure distribution around a steamlike body and J. G. Coffin has actually designed and used a container that rotates periodically. He found that when the aperture was 45° either side of the head-on position the observed pressure was normal or true static.

From all the above, it is evident that hereafter in the charting and discussion of storm centers at sea, as based on pressure readings, we must know whether the ships were headed east or west, the angle of inclination of the ship to the wind, the speed of the ship and the speed, direction and gustiness of the wind. ALEXANDER MCADIE

BLUE HILL OBSERVATORY,
January 20, 1920

STATE REWARDS FOR MEDICAL

DISCOVERIES

A REPORT has been issued by a joint committee of the British Medical Association and

of the British Science Guild, which has been considering the question of awards for medical discoveries. According to the abstract in the Journal of the American Medical Association the committee defines medical discoveries as being: (1) the ascertainment of new facts or theorems bearing on the human body in health and on the nature, prevention, cure or mitigration of injuries and diseases; (2) the invention of new methods or instruments for the improvement of sanitary, medical and surgical practise, or of scientific and pathologic work. The reasons given for rewarding medical discoveries are the encouragement of medical investigation and the discharge of a moral obligation incurred by the public for its use of private effort. The various public types of rewards are cited as; titles and honors given by the state, by universities and other public bodies; prizes and medals; patents; promotion and appointments; pecuniary rewards by the state. Concerning the general principle of assessment, the committee hold that, in the interests of the public, all medical discoveries should if possible receive some kind of acknowledgment or recompense. But in view of the variable conditions, nature and effects of particular investigations, it will often be difficult to assess the kind of recompense suitable. In the first place, a distinction should be drawn between compensation and reward. By compensation is meant an act of justice done to reimburse losses; by reward an act of grace in appreciation of services. The following different cases should be considered: A. Discoveries involving pecuniary or other loss either by direct monetary sacrifice or by expenditure of time, or by diminution of professional practise, without corresponding pecuniary gains. An example is that of Jenner, who occupied himself so closely with the investigation of vaccination that he lost most of his medical practise and also a considerable sum in expenses. This was fully acknowledge by Parliament, which granted him $150,000. B. Discoveries that have increased the professional emoluments of the investigator by enhanced practise or other means.

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