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Salts and their Reactions. By Dr. L. Dobbie and H. ing out behind (Phil. Trans., A, ccii. p. 346, corrected by

Marshall. Pp. 198. (Edinburgh: James Thin, final note). Hence we have 1904.) Price 3s. 6d. net.

Retarding force This book is intended to serve as an introduction to

Solar repulsion 30 the study of practical chemistry, and has for its basis a series of notes intended for use in the Edinburgh At the earth's distance u/U is about 10-*, so that the reclasses. In an interesting preface Prof. Crum Brown tarding force is about 1/30,000 of the solar repulsion states his belief in the possibility of devising a course If we take S/U as 5.8x10-5 dyne/sq. cm. (Phil. Trans., that would be “ something better than a mechanical loc. cit., p. 539), and the radius of the earth as training to enable students to pass a mechanical ex- 6-37% 10%


the total solar repulsion is about amination consisting in the detection of simple salts

75 X 100 kgm., say 75,000 tons, and the retarding force is in solution." Notwithstanding this assurance, one

about 2500 kgm.

But another effect comes in which will more than counterfinds that about half the book consists of descriptions

balance this. The hemisphere of the earth which is of the ordinary tests and schemes of analysis common

advancing in the orbit is on the whole colder than that to most books treating of elementary practical which is retreating, owing to the lag in the warming of chemistry.

the surface exposed to the sun. I find that if one hemisphere The first part of the work consists of a short and is at 301° A. and the other at 300° A., the greater radiation very clear account of the general physical properties from the warmer side gives a net push directed from tha! of salts and salt solutions. An outline is given of the side to the colder of about 165,000 kgm. Of course this ionisation hypothesis and of its applications, some of hemispherical distribution of temperature is only a rough which are practically illustrated at a later stage. approximation to the real condition, and even if the force be After a short account of the nature and use of in- as large as 165,000 kgm. only a component of it acts along dicators, a chapter is devoted to alkalimetry and

the orbit tending to accelerate the motion. Still, that com. acidimetry. The experimental part of the book, ex

ponent must almost certainly be much greater than the recluding the sections on qualitative analysis, is only tarding force due to the Doppler effect, and on the whole, represented by about twenty-five pages, and although

therefore, there is probably a small acceleration in the orbit.

A force of 2500 kgm. would destroy about 4'10" of the the selection of experiments has evidently been care

earth's momentum in one year. Even if the accelerating fully made, it seems a pity that the practical illustra

force were twenty-five times as great as this it would only tion of a really excellent theoretical introduction should generate 1/10 of the present momentum in one year. be so meagre.

This illustrates the insignificance of radiation pressure on The remainder of the book is taken up with a de- the larger bodies in the solar system. scription of the reactions of metallic and salt radicals, I take this opportunity of correcting another error in the and with schemes for analysis. In several small par- address in NATURE of September 22, which has been pointed ticulars a departure from the conventional methods out to me by Mr. C. T. Whitmell. It arose from some very has been made with distinct advantage. Dry-way faulty arithmetic on p. 541 of the paper in the Philosophical reactions, which so few chemists appear to appreciate,

Transactions already referred to. Apparently in the formula are relegated to an appendix, which also contains the giving the radius of each of two equal spheres the mutual inevitable and perfectly useless description of the re

radiation-repulsion of which balances their gravitative actions of the so-called rare elements. Teachers who

attraction, a square root of 10 was omitted, and the value

of that radius should be a=0.698°/10*p. A wrong value have the management of large practical classes should

was also assigned to the density of the sun. Mr. Whitmell find the volume of value.

has very kindly re-calculated the results depending on this formula, and I have worked them out independently. We now find that two equal spheres will have equal radiation

repulsion, and gravitative attraction with radii as given LETTERS TO THE EDITOR.

below :[The Editor does not hold himself responsible for opinions Temperature

Radius in expressed by his correspondents. Neither can he undertake


centimetres to return, or to correspond with the writers of, rejected


1930 manuscripts intended for this or any other part of NATURE.


6:1 No notice is taken of anonymous communications.]


0-5645 Radiation Pressure.


113 Os p. 515 of your issue of September 22 I stated that The last was given previously as 3-4 cm. there is a retarding force.on the earth as it moves along its The effect of radiation pressure on terrestrial dust is orbit amounting in all to about 20 kgm. The calculation worthy of consideration, for it may be quite appreciable was made on the supposition that the earth is a full radiator when the particles are small and are among surroundings of uniform temperature. I have found on revising the at different temperatures. For simplicity of calculation, let calculation that there was an error in the arithmetic, and

us suppose very small dust particle, of density p. to be that the force is considerably greater, though still too small cylindrical with radius a and length a, and let its fiat ends to have an effect worth considering. The following is a be black and let its curved surface be perfectly reflecting: simple method of obtaining its value. It assumes that the

Let it be situated between two indefinitely extended parallel earth may be treated as a black sphere exposed to sun- vertical walls, one at a temperature 0° A., the other at a light, radiating as much as it receives, and with all its lower temperature 0,9 A., and let its ends be parallel to the surface at one temperature.

walls. The two faces of the dust particle will, if it is small If the stream of solar energy falling normally enough, be at very nearly the same temperature, so that 1 sq. cm. is S per second, a black sphere, radius a,

we may leave out of account the pressures due to the emitted receives na’S per second. If it radiates R per second per radiation and consider only those due to that received from sq. cm. its total radiation is 4 aʼR, and the assumption of the walls. Ifo is the radiation constant 5:32 X 10-5, and if equal receipt and expenditure gives R=S! 4. The total U is the velocity of light, the difference of pressure on the repulsive force exerted by the sun's radiation is Sma”, U,

two sides will be 20(0,4-0,4)/3U, and the acceleration due where U is the velocity of light. The total retarding force to this on area ma’ and mass pra is 200, -0,9/3Upa, due to velocity u in the orbit is 4/3 Ru ! (12.7 a?. This is the

When p=1, a=10-8, A, = 400° A., fa=300° A., this accelerDoppler effect due to crowding of energy in front and open- ation is 0.02 cm.

m. / sec.,'

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If the law of radiation pressure can be taken as still holding when the radius is reduced to a = 10-s, the acceleration is 2 cm. / sec.'. This implies that such a particle of dust, in a vacuum, and between vertical walls respectively at 27° C. and 127° C. would not fall vertically, but would deviate about 2 mm. per metre towards the colder wall.

The effect found by Prof. Osborne Reynolds (Phil. Trans., ii., 1879, p. 770) on a silk fibre exposed to radiation from a hot body, and assigned by him to radiometer " action, is far larger than this. The radius of the fibre was 0 000625 cm., and its length was probably about 15 cm. When it was hung up in a test tube containing hydrogen at atmospheric pressure, and was exposed to radiation from a neighbouring jar filled with boiling water, the lower end of the fibre moved through 0.01 cm. This would imply an acceleration of about 0.7 cm./ sec. , about sixty times the acceleration on a dust particle of the same radius under the conditions assumed above. The action detected by Reynolds increased, too, very rapidly as the pressure fell, being ten times as great when the pressure was reduced to 1 inch of mercury.

J. H. POYNTING, The University, Birmingham, December 15.

an affinity has never appeared to me to be probable. The characters cited-the presence of an integument and micropyle, the single functional megaspore, and the detachment of the indehiscent, seed-like organ as a whole-are important points of analogy with true seeds, but in Lepidocarpon " these organs differ too much in detail from the seeds of Gymnosperms to afford any evidence of affinity.” ? I doubt whether my friend Mr. Smedley really intended to suggest anything more than an analogy.

As regards the Gymnosperms, evidence has been accumulating for some time past indicating their connection with the fern-phylum rather than with the Lycopods. Some account of this evidence will be found in my discourse at the Royal Institution on the origin of seed-bearing plants (1903)," while a more recent summary is given in Mr. Arber's article on Palæozoic seed-plants in NATURE for November 17, p. 68.

The seed-like organs of some Palæozoic Lycopods, such as Lepidocarpon and Miadesmia, seem to be cases of homoplastic modification, and not to be indicative of any affinity with those groups of seed-plants which have come down to our own day.

D. H. Scott. Jodrell Laboratory, Kew.


Fishing at Night. The notice in your Journal of the “ Sea Fishing Industry," written by Mr. Analo, suggests to me that he or some other of your readers may inform me why sea fishing takes place for the most part at night. I have heard the subject discussed all my life, and the answers have been of the most opposite and unsatisfactory character, such as to obtain a supply of fish for the morning markets, and because fish come nearer to the surface in the dark. Everyone must be familiar with the sight of our fishing boats preparing to take their departure as the evening approaches in the different harbours on our coasts. Some of the masters, unfortunately, like the Apostle Peter, have toiled all night and caught nothing.

S. W. December 20.

The Date of Easter in 1905. ALREADY queries have been addressed to me on the subject of the date of Easter in 1905, owing to the fact that, according to the almanacs, the moon is full at 4h. 56m. Greenwich mean time on the morning of March 21 next, and that therefore, according to the Prayer Book rule, it would appear that Easter Day should be the Sunday following March 21, viz. March 26. As the misunderstanding on the subject seems widely spread, perhaps you will allow me to explain that the “ moon " referred to in the ecclesiastical calendar is not the actual moon in the sky, which is full at a definite instant of time, but a fictitious moon, the times of the phases of which are so arranged as not to differ much from those of the actual moon. These phases are held to occur, vaguely, on certain days, and therefore hold good for all longitudes, and so avoid a practical inconvenience that would arise from the use of the actual moon. Thus, in the instance before us, in which the actual moon is full at th. 56m. a.m. Greenwich mean time, the same moon is full at uh. 48m. p.m. (on the preceding day) Washington mean time. The people adopting Greenwich time would, therefore, in the supposed circumstances, keep Easter Day on March 26, whilst those adopting Washington time would kerp it on April 23.

Perhaps the simplest expression for the date of the Paschal full moon is March (44 - epact), which gives the date directly when the epact is less than 24. When the epact is equal to or greater than 24, this expression gives the date of the preceding full moon, and the Paschal full moon is found by adding 29 to this date.

Thus in 1905 the epact is 24, therefore the calendar moon is full on March 20, and again on April 18. The latter is, by the rule, the Paschal full moon, and Easter Day is the following Sunday, viz. April 23.

A. M. W. DOWNING. H.M. Nautical Almanac Office.

A New British Bird ! A FINE example, a male, of the Pacific eider-duck, Somateria v-nigrum, was killed at Scarborough on December 16. This is the first recorded instance of the occurrence of this bird on our shores. Closely resembling the common eider, Somateria molissima, it may yet be readily distinguished therefrom by the bright orange colour of the bill, and the sharply defined, black V-shaped mark on the throat-hence the specific name v-nigrum.

The Pacific eider occurs in abundance along the coasts of north-western America and north-eastern Asia:

W. P. PYCRAFT. Natural History Museum, South Kensington.

Lepidocarpon and the Gymnosperms. The concluding sentence in your note on Mr. H. E. H. Smedley's admirable models of the fructifications of Paleozoic plants (NATURE, December 22, P. 183) may possibly be misleading to some of your readers. As the models of Lepidocarpon shown in your figure were prepared from my instructions, I may be supposed to share the responsibility for the hypothesis of an affinity between the lycopodiaceous cones and the Gymnosperms, stated to have been urged by “ the author," especially as the points of agreement mentioned are quoted, with some slight abridgment, from my paper on the seed-like fructification of Lepidocarpon in the Philosophical Transactions.' Such

1} &l. Trans. R.S., Series B, vol.cxciv., 1901, p. 320. See also NATURE, Vinm., 1900 1901, pp. 122 and 506.

Intelligence of Animals. In reference to the question of intelligence in animals, it may be of interest to mention a case of distinct reasoning power in a cat which for nine or ten years associated himself with our family; he would have scorned the suggestion that he belonged to it. When he found himself on the wrong side of a closed door--a very constant occurrence-he stood up and, catching the handle in his fore paws, rattled it. I do not think he tried to turn the handle, but he certainly knew that it played an essential part in the opening of the door. He is now no more, and de mortuis nil nisi bonum bars any further reference to his career, for he was a dissipated old scoundrel; but it is a pleasure to me to pay, with your permission, the above little tribute to his memory. Greenock, December 17.

T. S. PATTERSON. 1 Phil. Trans., loc. cit, p. 324. 2 NATURE, vol. Ixviii., p. 377. 3 Miss M. Benson, "A New Lycopodiaceous Seed-like Organ," New Phytolovist, vol. i., 1902, p. 58.

struggle for existence amid which some species are FAUNA OF THE HIGHLANDS."

still advancing. What Mr. Harvie-Brown particularly

Harvie Brown's“ Vertebrate Fauna of Scotland ”main- is a main reason for its faunal poverty; thus some of tains the high standard of excellence which has marked the more prominent land-features of the country, such the preceding volumes. It is punctiliously accurate as the long tongue of land of Ardnamurchan, act as and at the same time picturesque and full of interest. deterrents to the advance of land birds from south to One of the authors, the Rev. H. A. MacPherson, sacrificed himself too whole-heartedly an enthusiasm for ornithology, and died in 1901 at the age of forty-three, and Mr. Harvie-Brown has also to deplore the loss of another collaborator, Mr. T. E. Buckley, who died in 1902. Of both these naturalists there are appropriate in memoriam sketches.

This volume deals specially with the western parts of the counties of Sutherland and Cromarty --West of the great “watershed ”—and with similar portions of Rossshire and Inverness-shire down to the boundary of “ Argyll.” In the introductory matter we find terse physiographical accounts of Skye, the Ascrib Islands, Handa, Priest Island, and the coast of the mainland, designed to illustrate the most outstanding faunal feature of

the area, namely, its isolation. Mr. Lionel W. Hinxman contributes a brief account of the geology of the northwest Highlands, and there is another interesting section dealing with climatic and other changes, including those due to the hand of man. Few of these can be said to do man's intelligence much credit.

Mr. Harvie-Brown confesses that the chief interest of the area in question is the comparative poverty of its fauna. “ The true faunal value lies in its isolation by sea and mountain ranges. " It appears to me to be almost the poorest and least favoured of our Scottish Faunal Areas, Fig. 1.–Fulmar's first nesting place on Handa (at small white X). From "A Fauna of the North-West both as regards species

Highlands and Skye." and in its paucity of individuals of many of them." But it includes | north. The nature of the soil, the vegetation, the dissome old frequented haunts of some of our tribution and character of wooded areas, and the rarer birds, it illustrates faunistic changes traceable climatic conditions have also to be borne in mind, but to climatic changes, and it gives evidence of a keen Mr. Harvie-Brown has not done justice to himself or

to his theme in his treatment of this aspect of the 1. “A Fauna of the North-West Highlands and Skye." By : A. Harvie problem. Of course it is not given to everyone to be Brown H. A. . (Edinburgh: David Douglas.) Price 305

a Humboldt, but without attaining to his compre


hensiveness of outlook it would not have been difficult The book is beautifully got up and illustrated, and to improve the chapter on the “Faunal Position" of though, unfortunately, somewhat of a luxury, is sure the area in question; and even in regard to the par- to be welcomed by those who are interested in the ticular factors which Mr. Harvie-Brown emphasises wild life of Scotland. Its mood is one that will foster in his interpretation of the faunistic peculiarities of the interest in open-air natural history, and the thoroughareas, his " argument," as he calls it, appears to us too ness of its lists should help to lessen the ruthless jerky and elliptical to win conviction. But he gives killing of supposed rarities.

J. A. T. some references to papers dealing with the physiographical conditions in some detail. Turning to the list of mammals—which is somewhat

A NATURALIST IN SARAWAK." mournful-we find that there is only one bat, the NE

EARLY forty years ago Dr. Beccari, the well pipistrelle; the hedgehog, the lesser shrew, and the known traveller-naturalist, made extensive water-shrew are rare; the true wild cat still lingers; journeys in Sarawak, but not until now has he pubfoxes, once very numerous, are now scarce; the marten, lished an account of his experiences; indeed, for this once abundant, is trembling in the balance between volume we have to thank the Ranee, H.H. Lady Tarity and extinction; the polecat has become decidedly Brooke, who wisely urged Dr. Beccari to give the rare; a colony of badgers still persists; the rabbit, intro- public the benefit of his knowledge, for, as she justly duced about 1850, is in many places taking a rapid, stated, the conditions have practically remained unlamentably rapid-hold of newly afforested grounds; changed from times unknown. and so on. The chief value of such information lies in the precision with which it records increase or decrease, €.g. of squirrel and polecat, within a term of years, and thus illustrates evolutionary processes going on around us.

We need hardly refer to the records of adder, lizard, and slow worm, of frog and toad, and two newts; but we may be allowed to note, without being captious, that the title on the back of the book and on the beautiful frontispiece, “A Fauna of the North-West Highlands and Skye,” is somewhat too big for the volume, which deals with mammals, birds, reptiles, and amphibians, and no more.

The most entertaining part of the book is that which deals with the birds, in regard to which the authors speak from rich experience and with infectious enthusiasm, There is naturally enough a dominant note personnel, but it is always pleasant, even when the information given does not seem very important. Among the rare visitors we may mention the lesser whitethroat, the barred warbler, the nuthatch, the golden oriole, the great grey shrike, the waxwing, the rose-coloured pastor, the roller, the hoopoe, the osprey, the bitten, Pallas's sand-grouse, the rednecked phalarope, the great crested grebe, and the fulmar. Among the most interesting residents are the chough, the raven, the hen-harrier, the sea-eagle, the rock dove, and the ptarmigan. This section is rich in historical material, e.g. in regard to the

Fig. 1.-Adult Male Mayas Tjaping. From Wanderings in the Great Forests of Borneo.' starling, the golden eagle, the seaeagle, the osprey, the grey lag goose, and the Dr. Beccari collected in the land of the Land Dyaks, fulmar. .Ipart from their historical interest, the of the Sea Dyaks, and of the Kayans, not to mention notes on the birds are full of interesting observa- less numerous peoples, and he gives a first-hand tions, and some of the descriptions by the late account of the people, their houses, dress, weapons, and Mr. MacPherson are fine pieces of picturesque writing.

All this is very interesting reading, but there Mr. Harvie-Brown gives here and there an inkling is little, if anything, that has not been recorded in of his strong views on bird protection; thus, “the Ling Roth's great compilation “ The Natives of Bird Acts require steady and relentless revision and Sarawak and British North Borneo,' or in the writings change. The idea of saving trouble at Westminster of more recent travellers. Indeed, it is the great fault and County Council and Sheriff Courts, by dividing of this book that the numerous contributions that have Great Scotland into two divisions-north and south- of late years been made to the natural history and for all species mentioned in these Acts, is absurd, and 1 "Wanderings in the Great Forests of Borneo: Travels and Researches appears to me to be eminently calculated to defeat all

of a Naturalist in Sarawak." By O. Beccari 'Iranslated by Dr. E. H

Giglioli, and revised and edited by F. H. H. Guillemard. Pp. xxiv + 424 useful purposes of the Acts.'

illustrated. (London : A. Constable and Co., 1904.) Price 16s. net




ethnology of Sarawak are one and all ignored. A few opinion that at least two species of orang-utan exist references are given to older publications or the in Borneo Dr. Beccari has come to the following Sarawak Gazette, and to some of the papers based on conclusions :—There is no well authenticated case of a the collections sent home by Dr. Beccari. The reader female with lateral face-expansions, though there is must consequently bear in mind that there is a con- some evidence that such do occur; but there are young siderable amount of information about the animals and orangs with milk dentition which have them well depeople of Sarawak which, to say the least of it, supple. veloped, and adult male individuals are found with ments Dr. Beccari's book. To the ethnologist the the expansions rudimentary. Not associated with the chief value of the book lies in the identification of above character is the frequent absence of the terminal animals, and especially of plants, employed by the phalange of the hallux with the total or partial supnatives, as the author not only gives their uses, but pression of the nail. Evidently there is great varitheir native and scientific names.

ability in the orang, but Dr. Beccari holds that there is The general naturalist will find the book packed only one species of Simia satyrus with two main variewith interesting, information. Dr. ties, "tjaping” with lateral adipose cheek-expansions enthusiastic and keen witted field naturalist. The in- and highly developed cranial crests, and “kassa" tending traveller will pick up many valuable sugges- with no lateral cheek-expansions and its skull devoid tions, and the stay-at-home naturalist will gain an of strongly pronounced crests. Nevertheless, he extremely good idea of the conditions of life in the suggests " that in a remote past the Mayas tjaping



Fig. 2.--Ra Mesia Tua 1-Mudæ, Becc. (flower 22 inches in diameter). From “ Wanderings in the Great Forests of Borneo.'


jungles of Borneo. The author not only describes and the Mayas kassa were two quite distinct species, what he saw, but he seeks to trace the interdependence perhaps having their origin in separate regions, and of organisms upon one another and their relations to only later coming into contact on the same area the environment. As Dr. Beccari is a professional at present it seems hardly likely that the two races botanist, the botany of a tropical forest is dealt with should remain distinct." Dr. Beccari brought home more fully and with greater knowledge than is usual a large number of skins, skeletons, and heads of these in similar books, and those botanists who are interested animals, and he confesses to have killed and wounded in ecology will find much that will be of service to others which he could not take away. He adds them.

practically nothing to our knowledge of their habits. The most important zoological observations are Dr. Beccari does not hesitate to throw out a number those on the orang-utan. The Dyaks recognise of hypotheses, many of which will by no means be several varieties of orang, the two more important implicitly accepted by biologists; for example, he being the “Mayas kassa " and the “Mayas tjaping,' suggests (p. 32) that the prominent nose with narrow with a laminar lateral expansion of naked skin in front nostrils directed downwards of the Semitic people is of each ear. (In a foot-note we read that tjaping, in associated with living in an open country," whilst Malay, is the term applied to a small, nearly triangular Negroes and Malays, for the most part dwellers in the piece of silver which is hung in front of baby girls forest, have snub noses with wide nostriis turned upas a fig-leaf.) Wallace and others have expressed the wards, such as characterise most monkeys." Again,

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