Lapas attēli
PDF
ePub

characteristic of continental sediments, the should always go together in the manner local breaks not representing a loss of geologic assumed. A simple explanation is supplied time of any marked historical value."

on the weak-allelomorph view, for Ee is the The plants certainly do not uphold this weak allelomorph and the selective reduction contention, but they do indicate a very con

Ee

ce is simply segregation in the en siderable hiatus between the top of the compound. Linkage supplies the explanation acknowledged marine Cretaceous section and

on the modifier view, for the E is then a domithe inauguration of the Lance. The Laramie

nant minus modifier in the fourth chromois not known within this area, but can it be

some, and Ee

e is simply Moe - e. As far doubted that it was the interval during which

as can be judged from the short account given, in other areas beds of Laramie age were laid

all the observed ratios are in conformity with down and subsequently removed in whole or

either of these views. Thus, Dr. Little has not in part? That there was an important inter

proved by direct and available means that the val of some kind is also shown by the fact

case is actually one of non-disjunction, nor that it was sufficiently long for over 60 per

has he proved it negatively by excluding wellcent. of the marine Cannonball fauna to be

recognized alternative hypotheses which are derived through modification of the typical

equally valid and even more in harmony with Fox Hills fauna.

F. H. KNOWLTON
the facts of the case as stated.

C. B. BRIDGES
PROOF OF NON-DISJUNCTION FOR THE
FOURTH CHROMOSOME OF DROSO-

SURVEYING FROM THE AIR
PHILA MELANOGASTER
DURING the spring and summer of 1920 I

The article on Surveying from the Air," secured genetic evidence that strains of D.

December 17, 1920, is a summary of the work melanogaster haploid for the fourth chromo- of the Coast and Geodetic Survey along the some had been produced by non-disjunction,

lines of aerial photography, and of necessity and in November cytological verification was

does not go into the requisite detail regarding obtained. The fact that non-disjunction of

the reasons for making the following statethe fourth chromosome is known to occur is

ment: perhaps the strongest reason for believeing These experiments proved very conclusively that that the aberrations observed by Dr. Little photographs from the air, using present-day equipmay be the consequences of non-disjunction. ment, are of little practical value to the hydroThe direct evidence presented by Dr. Little by grapher. no means proves such to be the case, which is This statement has been noted by Mr. Willis unfortunate, considering the ample means in T. Lee, of the U. S. Geological Survey in D. melanogaster for checking up this hy- SCIENCE, February 18, 1921, who cites Comptes pothesis by means of other fourth-chromo- Rendus Tome 169, October 27, 1919, in which some mutants (bent, shaven) and especially by mention is made of experiments near Brest direct cytological examination. Probably Dr. where successful photographs were obtained Little will include such evidence in his forth- of the bottom at a maximum depth of 17 coming detailed report. For the present, his meters. published evidence is in better conformity During the experiments at Key West, the with the assumption of a less extreme eyeless results of which were the only allelomorph, or of a dominant fourth-chrono- known to me, occasional successful photosome

minus” modifier. On the non-dis- graphs of the bottom were obtained in depths junctional view selective reduction of the of 35 feet and less. No attempt was made to three fourth chromosomes present is required, photograph at greater depths. When the conbut there is no obvious reason why E and e clusion regarding the “practical value” of the 1 SCIENCE, 53: 167.

photographs was arrived at, all factors re

ones then

crew.

garding their use for hydrographic purposes coast where enough land stations would apwere considered. Obviously, a comparison pear for control, but these areas are generally was made with the present-day methods of in bays or rivers where water is not clear hydrographic surveying.

enough for good photographic work. Buoys It may be argued that aerial photography or rafts may be used as control points, but is more rapid, because a photograph of more the cost and labor of handling them would than one square mile is made in a fraction of be excessive. A raft about 10 feet in diameter a second, and a strip 70 miles long and over would be needed in order to be legible on a a mile wide can be photographed in an hour. 1:10,000 scale photograph. The problem of There are several problems to be overcome by handling a large number of these floating both the aviator and the hydrographer before signals would require a good sized vessel and this can be done. Weather conditions along the sea coast are not as suitable for aerial The uncertainty of results is another factor. photography as might be expected. Let us The French have solved some of the problems see how the photographs as made by the by using the stereoscope, so that the confuFrench would apply to our waters. These sion, brought about by vari-colored bottom of photographs were made under the following uniform depth, is partly eliminated. Some conditions: Focal plane horizontal; altitude, shoals will show clearly, while others close by 2,600 meters; at time of low water; the sun do not appear in the photograph, probably due high above the horizon; calm sea. Along the to a difference in color or lighting. The coast of the United States, a calm day is gen- photographs will not record all shoals as seen erally hazy, so much so that it is impossible by the aviator. It is often necessary to fly to make photographs from an altitude of even over the same area repeatedly in order to ob4,000 feet without special treatment of plates tain good results. or films. We are aware of recent experiments Unless ideal conditions prevail, the cost of regarding the penetration of haze, but at the

an aerial survey with present-day equipment, time the Key West experiments were made, will far exceed that of a wire drag survey, little was known of this new process. Further

and will not give as certain results. We bedevelopments may make it possible to pene- liore that aerial photo-hydrography is of some trate haze at altitudes of 2,600 meters. But use in a few limited locations, and there are disregarding haze, those days that are calm

possibilities of future development, but at the and cloudless are infrequent. It is difficult

present date, revision work by photographs on to obtain data regarding meteorological con

land holds forth greater promise, and is one ditions as affecting aerial photography along

in which more certain results can be obtained. the coast, but from available data, it is ven

It may be of interest to quote a sentence tured that about one day a month would ful

from a letter dated January 10, 1921, from fill conditions as called for by the French,

Le Directeur du Service Hydrographique adand that is believed to be an optimistic esti

dressed to the Director of the Coast and Geomate.

detic Survey, in which the following stateRegarding control for the photographs, very

ment is made regarding aerial photography few places along our coast are as ideally fitted

along the coast of Syria in 1920. for control of aerial protographs as the area chosen near Brest. This locality is dotted

Los circonstances n'ont d'ailleurs pas permis de with numerous small islets, and ample control

l'employer systematiquement. (The circumstances could be obtained for each photograph. At

do not, however, permit of its systematic use). Key West, it was necessary to use boats as A careful analysis of the conclusion reached control points, so that the speed at which an in the article "Surveying from the Air," espearea was covered was limited to the speed of cially of the qualifying words " using presentthe vessels. There are a few places along our day equipment," and "little practical value,"

will probably derive the result that the statement is not as hastily worded as it was first thought to be.

E. LESTER JONES

SCIENTIFIC BOOKS Physics of the Air. By W. J. HUMPHREYS,

C.E., Ph.D., Professor U. S. Weather Bureau, Philadelphia. Published for the Franklin Institute by J. B. Lippincott Co., 1920.

Professor Humphreys states in his introduction that “it is obvious that an orderly assemblage of all those facts and theories that together might be called the Physics of tho Air, would be exceedingly helpful to the student of atmospherics.”

Of this there can be no doubt, and the author has rendered a great service by thus bringing together and making easily available material that otherwise would have remained scattered through technical magazines, official publications like the Monthly Weather Review and journals of organizations like the Royal Meteorological Society.

The volume had its inception in a series of lectures delivered by Dr. Humphreys at the San Diego Aviation School in 1914. These lectures revised and printed from month to month in the Journal of the Franklin Institute, 1917, 1918, 1919 and 1920, are now consolidated in one volume.

As late as 1917 our military authorities failed to appreciate the importance of a knowledge of aerography, that is, the structure of the atmosphere. In June of that year a high officer of the Signal Corps, at that time entrusted with aviation, wrote:

It has frequently happened in the past that men who might otherwise have made good pilots became so alarmed in advance over the subject of “holes in the air” and so impressed with the terrible dangers of aerial navigation, that they never succeeded in gaining the necessary confidence to become good pilots, etc.

This was given as a valid reason for refusing to utilize recent advances in meteorology! And again :

So little time is available and so great the necessity for extreme haste in preparing aviators for service overseas that there is no opportunity to give more than the elements of meteorology in one or two lectures.

These views are referred to here, simply to show in some measure the amount of official inertia which had to be overcome. After many promising lives had been sacrificed, the need of the fullest knowledge possible was manifest; and before the war ended aerography had come into its own in both army and navy schools of instruction.

Professor Humphreys divides his treatise into four main parts; mechanics and thermodynamics; atmospheric electricity and auroras; atmospheric optics; and factors of climatic control. The author had the great advantage of access to the Weather Bureau Library, and critical readings by his colleagues. Furthermore, the text appeared in type before final publication. The work is unusually free from typographical errors.

There are a few slips, however. On page 49 the symbol for temperature of the isothermal region T might with advantage have been placed in front of the radical, or at least in some way separated more than at present. Again, it would be a gain if instead of saying that the temperature of a black radiator, in this case the earth, was 259° C. absolute, the author had used the more common form 259° A., adding if he thought it nécessary, in degrees C. It is desirable in a text-book to avoid confusion, by using consistent notation. The reviewer holds that it is not good form to speak of a given temperature as 259° C. absolute on one page and on the next page give a diagram expressing the same value in degrees Centigrade, that is, -14° C. One may expect to meet a slip from such loose practise and sure enough it

On pages 75 and 76 it is stated : The effective absolute temperature of the earth as a full radiator is approximately 260° C.

Rather a warm condition; but of course the author means that the effective temperature on a certain approximate absolute scale is

Occurs.

on

Winds

260°. There is a scale which might have been is no longer tenable; and there is not sufficient advantageously used here, namely the Kel- emphasis laid on the fact that the high rotavin-Kilograde scale. True, few are as yet tive values are hypothetical, not real so far as familiar with it; but the colors should always mobile air is involved. be in advance of the line, not abreast nor yet Chapter XI.,

Adverse to behind. In an up-to-date scientific book we Aviation,” explains the so-called “holes in have the right to expect leadership rather the air," " bumps," " dunts," etc. There is not than tolerance.

a mathematical symbol in the whole chapter. The airman has got to forget the unscien- The different phenomena are explained in tific, arbitrary scales of his fathers; and stop straightforward, simple language. However, using inches, minus signs, etc. His range of there is much yet to be learned in connection temperature is from summer day surface with favorable and adverse conditions; and values to winter sub-polar readings near the we await some Maury who will do with the stratosphere; and old-fashioned methods are logs of airships what the old Commodore did inadequate.

with the logs of the clippers of his day. Pressures are generally given in this book Chapter XIV. contains many photographs in millimeters of mercury with occasional of cloud forms, but neither here nor in the lapses into inches. In a treatise dated 1920, first chapter where many instruments are one might look for pressure values through- given, is mention made of a nephoscope. Fair out in units of force, that is, dynes or kilo- credit for cloud work done at Blue Hill Obdynes per square centimeter.

servatory is not given; nor is mention made In the chapter on “Atmospheric Circula- of Professor Bigelow's International Cloud tion” which is well put, and more clearly Report. explains the mechanics of deflection than most Chapter XV., on The Thunderstorm" has other text-books, it is demonstrated that in 105 pages, and yet is not included in Part II., the case of a wind with a velocity of 22 meters dealing with Atmospheric Electricity and per second, there will be a modification of Auroras, which has only 18 pages. velocity, depending upon whether the wind is Part III., on “Atmospheric Optics," has 129 blowing east or west; that is, a given mass pages and is based largely on the well-known weighs less going east than going west. A Pernter-Exner "Meteorologische Optik” and note might have been added giving results of Mascart's “ Traité d'Optique." recent gravity determinations at sea on fast- Part IV., 74 pages, deals with factors of moving (22-knot) destroyers (25-mile-per-hour climatic control, that is, in the author's words, vessels); in which it was definitely ascertained a discussion of the physics of climate and not that the barometric pressure changed 0.1 of its geographic distribution. The chief kilobar (0.075 mm.) when the course factors considered are latitude, brightness of reversed. Going east with the earth the the moon and planets, solar constant, solar centripetal force is greater than when steam- distance, obliquity of ecliptic, perihelion phase, ing west. All this is of importance in con- extent and composition of the atmosphere, nection with fast-moving airships.1

vulcanism, sun spots, land elevation, land and The discussion of change of velocity with water distribution, atmospheric circulation, latitude, deflective effect of the earth's rota- ocean circulation, and surface covering. tion, relative values of centrifugal and rota- Elaborate tables of gradient wind velocities tional components, and gradient winds, is are given in the appendix. We notice a few thorough and well expressed. Of course, the minor typographical errors. On page 136, explanation of friction acting as the effective latitude 10°, the change of direction is 20.61 damping factor against high rotational winds not 261, and the heading needs revising on

1 See SCIENCE, February 6, 1920; also ry page 162, m.m. should be mm.; on page 221, 9, 1920.

figure 31 should be 32; and on page 227, figure

was

57, the lengend should give the elevation of the 4. The application of names is determined station. ALEXANDER MCADIE by means of nomenclatural types.

Note.-A generic name is always so applied REPORT OF THE COMMITTEE ON

as to include its type species; a specific name NOMENCLATURE OF THE

is always so applied as to include its type BOTANICAL SOCIETY

specimen. OF AMERICA

Rules and Recommendations At the Baltimore meeting of the Botanical

Section 1. Publication of Names Society of America (1918), the Committee in

Article 1. A specific name is published Generic Types presented a set of rules for fix

when it has been printed and distributed with ing the types of genera. The report was pub

a description, or with a reference to a prelished in SCIENCE (49: 333–336. 1919). At the

viously published description. same meeting the committee was enlarged to

Note.-A recognizable figure may be the nine members and made a standing committee

equivalent of a description in the literature on botanical nomenclature, with authority to

of paleobotany and diatoms. prepare a code of nomenclature. The stand

(a) In the transfer of a species from one ing committee consists of Le Roy Abrams,

genus to another, the original specific name N. L. Britton, E. A. Burtt, A. W. Evans, J.

is retained, unless the resulting binomial has M. Greenman, A. S. Hitchcock, M. A. Howe,

been previously published. C. L. Shear and Witmer Stone. The actual

Recommendations: Botanists will do well, work of elaborating a code was done chiefly

in publishing: by a subcommittee consisting of J. C. Arthur,

1. In describing parasitic fungi to indicate J. H. Barnhart, R. S. Breed, N. L. Britton,

the host and to designate the name of the O. F. Cook, F. V. Coville, A. W. Evans, B.

host by its scientific Latin name. Fink, A. S. Hitchcock, M. A. Howe, F. H.

2. To give the etymology of all new generic Knowlton, P. L. Ricker, C. L. Shear and H. C. Skeels. The following code was presented by the committee:

Article 2. A generic name is published when it has been printed and distributed

(a) With a generic or specific description A TYPE-BASIS CODE OF BOTANICAL NOMENCLATURE

(or a recognizable figure, see Art. 1, note) and PRINCIPLES

a binomial specific name, 1. The primary object of formal nomenclature in systematic biology is to secure

(6) With a generic and specific name and stability, uniformity, and convenience in the

the citation of a previously published descrip

tion, designation of plants and animals. 2. Botanical nomenclature is treated as

(c) With a definite reference to at least beginning with the general application of

one previously published binomial. binomial names to plants (Linnæus' “Species

Note a.-A name is not published by its Plantarum," 1753).

citation in synonymy, nor by incidental men3. Priority of publication is a fundamental

tion. Such a name may be taken up but not principle of botanical nomenclature. Two

to replace one already properly published.

Note 6.-Of names published in the same groups of the same category can not bear the

work and at the same time, those having presame name. Note a.–This principle applies primarily to

cedence of position are to be regarded as

having priority. genera and species.

Note b.- Previous use of a name in zoology Recommendation: Botanists will do well, in does not preclude its use in botany; but the publishing, to give the etymology of specific proposal of such a name should be avoided. names when their meaning is not obvious.

names.

« iepriekšējāTurpināt »