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whole series of curves with other frequencies; (2) that the distinctness of the combination-tones would on this theory vary greatly with phase-relationship of the primaries; (3) that the tones would disappear when the energies of the primaries are not very unequal. Voigt applies a similar method to the case, where the upper tone is weak compared to the lower to account for Koenig's second beat-tone. The first of the above objections again applies. Everett supposed that the distortion of the vibration-curve in passing through the ear would bring in the note the frequency of which is the highest common factor of the primary frequencies. The effect of a special kind of distortion has been tested, consisting in a proportional reduction of ordinates in one direction. The result does not confirm Everett's contention, but shows the appearance of the summation and difference tones.--Miss Maud Saltmarsh Experiments on condensation nuclei produced in gases by ultra-violet light. (1) Nuclei produced in air by ultra-violet light which has traversed a few centimetres of air are not affected by an electric field of 50 volts per centimetre. (2) The nuclei are equally effective in producing condensation of water, toluol, and turpentine vapours, and they are formed even by light which has traversed 50 cm. of air. (3) Alcohol vapour condenses without expansion on much smaller nuclei than does water vapour. (4) No nuclei were formed by the light unless oxygen or CO, was present in the gas. (5) No trace of H2O, could be detected in the clouds formed on the nuclei. (6) Oxygen containing ozone also contains nuclei for condensation, and these nuclei have similar properties to those formed by ultra-violet light. (7) The nuclei can be destroyed by heating the air containing them. It seems probable that the nuclei formed by ultraviolet light do not cause condensation by virtue of any particular chemical composition, but that they are particles large enough to act like dust particles as centres round which condensation can begin.-S. Butterworth: The self-induction of solenoids of appreciable winding depth. The existing formulæ for coils of this type-viz., those of Rosa and Cohen-are shown to be inaccurate, the error amounting to onefifth of 1 per cent. for the best formula when the winding depth is one-tenth the diameter of the coil. For greater winding depths the error is larger. The inaccuracy in Rosa's formula is due to the neglect of curvature in correcting for thickness, while in Cohen's formula the error is due to the approximate method of development. New formulæ are developed by methods which are free from such approximations, and which apply to any coil for which the length is greater than twice the diameter, and the winding depth is less than one-tenth the diameter. These formulæ are capable of giving eight-figure accuracy. Simplified formulæ are also given which are suitable when only four-figure accuracy is required.
Mathematical Society, May 13.-Sir Joseph Larmor, president, in the chair.-Dr. Bromwich: The diffraction of waves (i) by a wedge, (ii) by a circular disc.W. E. H. Berwick: An invariant modular equation of the fifth order.-G. B. Mathews: A direct method in the multiplication theory of the lemniscate function.
Literary and Philosophical Society, April 27.--Mr. F. Nicholson, president, in the chair.-Prof. W. H. Lang: Studies in the morphology of Isoëtes:-Part iii., The structure and growth of the rhizophoric region of I. lacustris, and the development and arrangement of the roots. Part iv., The progressive growth of the young plant of I. lacustris, and the nature of the cortical extension of the stock. In part iii. the structure of the rhizophoric lower region of the stock of I. lacustris; the nature of its meri
stematic growth; the way in which the segmentation of the growing line leads to the growth of a rootbearing surface, exposed by the progressive splitting, and to the carriage outwards of the roots initiated close to the meristem are described in detail. The organisation of the central vascular axis of the rhizophore behind the meristematic line is shown to correspond remarkably to that of the stem-stele as described in part ii. The arrangement of the roots, their exogenous insertion, and the course of the root-traces are compared with the corresponding features of Stigmaria. În part iv., the progressive growth and organisation of the young plants of I. lacustris are traced from the stage of an advanced embryo to that at which a small plant exhibits adult characters as regards root- and leaf-arrangement. The symmetry of the plant is only evident when the second leaf and second root are developed. Further roots arise from a meristem established at the base of the vascular axis of the shoot long before any cambial activity has begun. The rhizophore continues from this meristem as a region of progressive growth, bearing roots acropetally. It may correspond strictly to the root-bearing region in Lepidodendreæ. The primary root in Isoëtes is lateral to the axis of the rhizophore; the construction of the plant thus appears fundamentally distinct from the Gymnosperms and Angiosperms, where the first root continues the axis of the plant and behaves as a taproot. The progressive cortical growth of the young plants of Isoëtes appears to continue uninterruptedly
into that of the adult stock.
May 11.-Prof. S. J. Hickson, president, in the chair.-Dr. Arthur Harden, Prof. W. W. Haldane Gee, and Dr. H. F. Coward: A report on the Dalton diagrams. A report on a collection of about 150 original pen-and-ink diagrams used by John Dalton. They describe the elementary principles of mechanics, heat, optics, and astronomy; the laws of expansion by heat; the special scale of temperature used by Dalton; meteorological subjects; and chemistry and the atomic theory. The diagrams dealing with the atomic theory show that Dalton used graphic formulæ for "compound atoms" much more frequently than would be suspected from a study of his printed books or notebooks. Many sheets illustrate the atomic composition of inorganic and organic substances. The latter are almost completely ignored in Dalton's published works, and in consequence his representation of them would be unknown at the present time were it not for the information disclosed by these diagrams. The formulæ are, however, very different from those now accepted. One of the diagrams is a list of atomic weights and symbols made in 1807, and is, so far as is known, the second list presented in public by him.
Academy of Sciences, May 10.-M. Ed. Perrier in the chair.-E. Bompiani: The equations of Laplace with equal invariants.-G. H. Hardy: The problem of divisors of Dirichlet.-Et. Delassus: The holonomial movements with multiple forms of Bagrange.-G. Chesneau: Contribution to the study of coloured glass of the Middle Ages. Analyses of violet, blue, green, and red glass, dating from the end of the thirteenth century, from Rheims Cathedral. The oxides of copper, nickel, cobalt, manganese, and iron were used as the colouring materials.-J. Bougault: The dioxytriazines. The synthesis of substituted semicarbazides. A method for preparing asymmetrical dioxytriazines has been given in a previous paper. These behave as acids towards alcohols, and give mono- and di-ethers in which the alkyl group is attached to nitrogen. The mono-alkylbenzyldioxytriazine on hydrolysis with boiling alkaline carbonate solution gives the alkylsemicarbazone of phenylpyruvic acid, and this, treated
The Morro Velho Method of Assay of Gold-Bearing Cyanide Soluticas
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in the cold with strong hydrochloric acid, gives the
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THURSDAY, MAY 27, 1915.
THE SCIENCE OF VULCANOLOGY. The Problem of Volcanism. By Dr. J. P. Iddings. Pp. xvi+273. (New Haven: Yale University Press; London : Oxford University Press, 1914.) Price 215. net.
explosive and eruptive actions of volcanoes could be accounted for by the access of sea-water to these incandescent materials through fissures in the earth's solid "crust." Now, after a full discussion of the astronomical, physical, chemical, and geological evidence involved, the author shows that there are no valid grounds against the conclusion that the earth's interior is solid and cold, and that all thermal action may be attributed to radioactivity, whilst many problems of far greater complexity than were ever thought of in the past await solution.
Although every outstanding branch of the inquiry meets with full and sympathetic treatment at the hands of the author, yet it is on the characteristics and relations of volcanic rocks that he writes with special authority, and more particularly on the light which has been thrown on petrology by microscopic research, the branch of study with which Dr. Iddings has been so long identified. But whether dealing with such problems as those belonging to his own studies or such varied questions as are suggested by the characters of nebulæ, Dr. Iddings is equally at home; and nowhere, to our knowledge, can there be found an account, so complete and illuminating, of all the varied lines of research bearing on the subject under discussion. A word of praise must be added for the numerous and beautiful illustrations, while the printing of the work exhibits all those excellences which we are accustomed to find in scientific works issued in the United States. J. W. J.
HIS work is the latest published of a series issued by the Yale University, acting as trustees for the Silliman Memorial Fund; the fund consists of the sum of 85,000 dollars left to provide for the delivery and publication of annual courses of lectures "to illustrate the presence and providence, the wisdom and goodness of God, as illustrated in the natural and moral world." Although the terms of the bequest strikingly recall those of the once-celebrated "Bridgewater Treatises," yet the testators of the Silliman Fund qualify the statement of terms by a declaration of a belief that "any orderly presentation of the facts of nature or history contributed to the ends of this foundation more effectively than any attempt to emphasise elements of doctrine or of creed." In the end they conclude that dogmatic and polemical theology should be excluded, and that "the subjects should be selected from the domains of natural science and history, giving special prominence to astronomy, chemistry, geology, and anatomy." A comparison of the terms of the Bridgewater and Silliman foundations give a by no means unsatisfactory impression of the improved relations between the representatives of natural science and theology which have arisen in the course of the last century.
LIQUIDS UNMATHEMATICALLY TREATED. (1) The Dynamics of Surfaces: an Introduction to the Study of Biological Surface Phenomena. By Prof. L. Michaelis; translated by W. H. Perkin. Pp. viii+118. (London: E. and F. N. Spon, Ltd., 1914.) Price 4s. net.
With characteristic impartiality the authorities of Yale University have invited representatives of various branches of science to give clear and upto-date presentments of the condition of our knowledge on the subjects selected by them. The successive courses of lectures have been given by Profs. J. J. Thomson, Sherrington, Rutherford, Bateson, and Sir W. Osler from this country; by Profs. Nernst and Max Verworn from Germany; and by Arrhenius from Sweden; only three of the published courses, indeed, are by American men of science.
(2) Motion of Liquids. By Lieut.-Col. R. De Villamil. Pp. xiv +210. (London: E. and F. N. Spon, Ltd., 1914.) Price 7s. 6d. net. (3) Liquid Drops and Globules: Their Formation and Movements. By C. R. Darling. Pp. x+ 83. (London: E. and F. N. Spon, Ltd., 1914.) Price 2s. 6d. net.
For the science of vulcanology no better representative could possibly have been found than Dr. Iddings, and no more striking illustration of the progress of investigation and theory could be given than his discussion of the problem. Fifty years ago the question was thought to be virtually settled by the assumption of a molten central mass constituting the earth's interior, or at least of pockets of such heated material at moderate depths; granted this, it was believed that all the
tion of the style in which the subject matter is treated, about seventeen pages are devoted to a discussion of surface tension of a far more elementary character than is usually presented to an average B.Sc pass candidate working in the laboratories of a British university, and on the other hand the thermodynamical formulæ which follow are written down without any consistent attempt at lucid explanation. Had the book been described under the last portion of the title alone it is not improbable that it might have proved of use to biological students who are weak in their knowledge of physics and chemistry, but even they would do well to remember that a little learning is a dangerous thing, and the danger is greatly increased when this small cargo of information is allowed to sail disguised under the flag of a highly mathematical treatise.
(2) In the matter of sailing under misleading colours, Col. De Villamil is another delinquent. He recently published an “A. B. C. of Hydrodynamics containing little or nothing on that subject which would be of use to a student pursuing a university course of study in hydrodynamics. By adopting a title closely resembling that of Lamb's classical treatise, he thrusts on our attention a small book devoted almost exclusively to common or garden hydraulics, and dealing far less with the actual motions of the fluids than with the resistances which they exert on solids. Many of his statements are not very clearly expressed; for instance, what does he mean by saying that “in an incompressible liquid which has no free surface and whose envelope is inextensible all bodies moving in steady motion in it are stream-line"? (p. 199), or, again, that “if any flat body of any shape be caused to move irrotationally round a fixed point, every point in the body will describe a figure which is an inverted reflexion of the body moving"? (p. 205).
Had Col. De Villamil claimed to write about "Practical Hydraulics," it is probable that a good deal of the subject matter of the book would have been of use to engineers. In posing as a mathematical physicist the author is probably defeating his own ends.
(3) Mr. Charles Darling's lectures on "Liquid Drops and Globules" present to an unscientific reader a simple and lucid exposition of a number of pretty experiments on liquids, many of which can be repeated by the most uninitiated at a trifling expense. The apparatus required is mostly of the simplest possible character, though for lecture purposes a lantern attachment is necessary. We note the author's recommendation of tap-water as superior to "distilled water, which often possesses a surface so greasy as to retard
or even entirely prevent the desired result." Curiously enough, the present reviewer's experiences in spreading diatoms on cover glasses have confirmed this difficulty of greasiness, and for mounting in resinous media the best results were frequently obtained by evaporating from a thick convex drop of ordinary filtered water heated to a high temperature, the impurities in the water being deposited round the edge of the cover, where they could be wiped off. The greasiness so often present in distilled water frequently caused the drop to tear away from the edges of the cover long before it had became reduced to a mere film, and often left actually more deposit on the diatoms than the less pure liquid. The same occurred when the drop was initially too thin.
Readers who are unable to specialise in science, but who wish to interest themselves in some of its developments, can do no better than study a book of this kind. The experiments described form a delightful recreation for those engaged in duties of a non-scientific character, and at the same time they are directed on such lines as are likely to give them the closest insight into the intricacies and difficulties of scientific investigation. G. H. B.
INSECTS AND MAN.
(1) Flies in Relation to Disease-Bloodsucking Flies. By Dr. E. Hindle. Pp. xv+398. (Cambridge: At the University Press, 1914.) Price 12s. 6d. net.
(2) Insects and Man. By C. A. Ealand. Pp. 343. (London: Grant Richards, Ltd., 1915.) Price
(1) HIS book is an attempt to combine in one volume the entomological information required by the doctor and the medical facts required by the entomologist, with regard to bloodsucking flies and the diseases they carry. The literature on this subject, being a special one, is very large, and is being added to daily. The whole subject is one that dates back only twenty years, and to attempt to present in a small compass a summary of these two aspects is no easy task. To do it successfully requires exceptional judgment in selecting what to omit and what to include, as well as a first-hand knowledge of both aspects of the subject. There is no evidence that the author has the latter, and the volume bears the impress of the laboratory, not of the tropics where these insects live and where men die daily from the diseases they carry. No one with actual tropical experience would omit from an account of measures taken against mosquitoes the use of traps and fumigants; no one with a first-hand
knowledge of insects would deal with technical points of entomology as is here done; the frontal suture is mixed up with the frontal lunule, the different venation systems are not tabulated, the value of the antennæ in classification is not made clear, there is an error about peripneustic, and so on. The volume, so far as the entomology goes, is largely a selection from Sharp's "Insects" (Cambridge Natural History) and Alcock's "Entomology for Medical Officers." These excellent works are, of course, listed in the references, but there does not seem to be any obvious reason for summarising parts of them.
The medical and the entomological student will find the references valuable. The doctor or sanitary officer who is not seeking special knowledge will find the volume a surprising revelation of the great importance attaching to this branch of entomology, and we wish it might do much to educate public opinion on this very vital point.
That is so more especially in England, where it is impossible to realise the part played by insects and the importance of these diseases. In this respect accuracy of technical detail and an up-todate summary of the scientific aspect is less important than picturesque description and lucid writing, both characteristics of this volume. We commend it to the public which reads general science, and to medical men desirous of keeping their knowledge of this subject up to date. It is well illustrated and produced, and an exceedingly readable volume.
(2) The author has put together a series of abstracts of published works on various phases of economic entomology under chapter headings such as "Insects and Human Disease," "Insects and Plants,' Beneficial Insects," and so on. the main, the work to which attention is given is that of the American worker, and the volume as a whole is very largely taken up with selections from recent American authors. The selection of subjects is curiously uneven quite obscure household pests are mentioned, while really serious ones are omitted; the bee as a honey-producer and the silk-worms are omitted while the Chinese waxinsect is discussed. In agricultural and horticultural entomology one gets the impression that, while much progress is being made in America, none is being made elsewhere. The Americans are quoted as the pioneers in the use of parasites to control pests, while the pioneer work of Perkins in Hawaii is not referred to.
The author lays no claim to first-hand knowledge of the subject, but has clearly read voluminously from American works. His abstracts are well written, but the accuracy due to personal knowledge of the subject is conspicuously absent. i
No one would contend, for instance, that "the control of scale insects and aphides, therefore, in such districts practically resolves itself into control of the ants," though the Argentine ant is, of course, a factor in spreading scale insects; nor would anyone conversant with the literature say of the codlin moth, "no insect of economic importance has received so much attention from entomologists." The curling of the leaves of Prunus is not caused by the fungus that lives on the secretion of the aphides; only a portion of the Coccidæ cover themselves with a scale; in no insect is the duration of the life-cycle to be "counted in hours ❞—and so on. It is far too easy to find misleading statements in general, which would not occur to an author who had other than a purely book knowledge. We would have suggested that to the title might be added the words "The romance of," for one feels that it is the "romantic" element of the journalist that guides the choice of subject; picturesque detail and local colouring is the object sought, and no methodical attempt has been made really to "compile a concise summary of the varied relations of insects and man," as the author claims (page 21). A great deal is said about certain sections of the subject, but the ground is not covered in any complete or methodical manner.
It is probably inevitable that a new subject will be exploited by the journalist seeking picturesque "copy," but we hope it will not again be presented in a serious form calculated to mislead the
student into thinking he has a concise summary of the subject; and if we must have such books as this, let us hope they will take into account the work done in this country and in our Colonies, every whit as good, though less blatantly set forth in sober reports, with no touch of the American journalese. We have to do a great deal yet to educate the British public (particularly the ruling class) to make them realise that there is a big future for economic entomology, but it will not be done by quotation from American entomologists, and the implication that they and they only can do the work.
H. M. L.
CULTURE AND METAPHYSICS.
(1) German Culture: the Contribution of the Ger
mans to Knowledge, Literature, Art, and Life. Edited by Prof. W. P. Paterson. Pp. x + 384. (London: T. C. and E. C. Jack, 1915.) Price 2s. 6d. net.
(2) The Principles of Understanding: an Introduction to Logic from the Standpoint of Personal Idealism. By H. Sturt. Pp. xiv +302. (Cambridge: At the University Press, 1915.) Price 5s. net.