births over deaths in 1880-90 would have been from 25 to 30 per cent. more than in the previous decade, or at least 9,500,000, whereas it appears to be under 7,000,000. The figures of the 1890 census are, therefore, quite incredible. The superintendent of the 1890 census has issued an explanation, which does not, we fear, amount to very much. He makes a great deal of the errors in the 1870 census, which we have already glanced at, and asserts that the rate of growth of population, when proper corrections are made, was much less than 30 per cent. in the 1870-80 period, so that the rate of 24 per cent. between 1880 and 1890 does not show a great falling off. But while he makes too much of the 1870 errors in amount, he makes no mention at all of the much larger immigration between 1880 and 1890 than in the previous decade, which should have made a difference of at least 3 per cent. in the rate of growth in favour of the latter as compared with the former period. A farther explanation is that there is a permanent tendency for the rate of growth of the population of a country like the United States to fall off. But this is not confirmed so far by any figures of a completely trustworthy kind, while the falling off in the rate of growth to be here accounted for is too great and sudden to be explained in such a manner. The blunder is thus left quite unexplained, and the people of the United States, we may hope, will not fail to see to it. It concerns wider than merely national interests that the blunder should be seen to. For purposes of comparison, every census in the world is thrown out. Looking at the causes of the errors in the 1870 census, viz. an attempt to understate the numbers of the people in Democratic States, and at the special complaints of under-statement which have now come from New York and other Democratic centres, we have altogether too much reason to fear that the cause of the blundering is political. But, whatever the cause may be, it should be stringently looked into. SPIDERS' WEBS. American Spiders and their Spinning Work: a Natural History of the Orb-weaving Spiders of the United States, with Special Regard to their Industry and Habits. By Henry C. McCook, D.D. Vol. II. pp. 1-479, with 5 Coloured Plates and 401 Woodcut Figures. (Philadelphia Allen Lane and Scott, 1890.) IN : Na notice of vol. i. of the above work (NATURE, vol. xlii. p. 244), its object and scope were explained. Vol. ii., now before us, fully justifies what was there stated as to the thoroughness with which the available materials on the subject have been brought together from all sources, and for the first time presented to the world as a whole. A similar popular treatment also of this interesting and most important part of the subject is again here observable. Vol. i. was occupied with the snares and web-spinning of orb-weaving and some other spiders, principally in relation to the getting of their livelihood. Vol. ii. treats of these spiders in respect to the propagation of their kind, and web-spinning as subservient to this. Vol. i., in fact, presents us with spiders safely arrived at maturity, and forming their snares and webs with all the diversity and perfection peculiar to each species; while vol. ii. takes them up at that point, and shows them to us in all the different peculiarities pertain ing to the performance of the ultimate object of their existence. Naturally, therefore, the volume before us begins (part i., chapter i.), with an account of the sexes in their relation to each other preparatory to actual pairing. This latter and the points arising out of it form the staple of chapters ii. and iii., which complete part i. A certain air of sentimental allusion, which appears to pervade the author's method of presenting this part of his subject, is perhaps merely a matter of taste, and so beyond the province of scientific criticism. It may be, however, that this, while it certainly adds nothing to scientific accuracy or progress, does add to the popularity of the subject, which is evidently throughout the work one of its author's great objects. On the small size of many male spiders compared with their bulky females, Dr. McCook does not appear to accept the views of a former writer upon it, in which it should be observed that the primitive equality in the size of the sexes is by no means implied; the general rule being that the male is the smaller of the two. But if it be granted that the female had a propensity for attacking and devouring the male, those males which happened to be the smallest and most active would be the most likely to escape, and perform the functions of the sex; natural selection would then come in, and operate gradually in the direction of lessening the size of the males. That there are numerous spiders, and groups of spiders, in which the sexes are nearly equal in size, or live in amity together, or in which the males are furnished with some protective armature against the ferocity of the female, proves nothing against the theory of the action of natural selection in lessening the size of the male in such cases as those where a devouring propensity existed and was otherwise unprovided against; for in groups where any approach to equality in size existed and became protective, or where some other protection became developed, there would be no need, in fact no case, for natural selection in the direction of diminished size, there being no advantage to be gained under it. The drift, however, of the author's reasoning on this subject (p. 7) is not very apparent. Part ii. treats of the "Maternal Industry and Instincts of Spiders"; embracing the formation of cocoons for the reception of their eggs, and the bringing into existence of the young, which naturally leads (part iii.) to the consideration of the life of the young while still engaged in the struggle for existence necessary for the survival of the fittest. The dispersion of spiders on the approach of maturity leads to an account of their method of locomotion on gossamer lines and flakes, completing part iii. Part iv. enters into the subject of the senses of spiders, and their relation to habit. The structure of the eyes, and their functions are gone into in considerable detail. The remarkable position of these organs in the males of some species-such as Walckenaera acuminata, Blackw., in which they are seated near or at the top of a very long slender kind of footstalk -is mentioned; and it is supposed (p. 298) that this might give the male spider an advantage when in search of the female; but, apart from this explanation not being warranted by any known facts as to the xii. of part v. is on that most interesting part of natural history in all its departments-resemblance to other objects both inanimate and animate, with the causes and consequences of the resemblance. Space will not permit us to follow the author in the details of this part of his subject. The chapter will be read with pleasure and interest by most observers; but we may perhaps remark that there is at times an apparent tendency to take inability to perceive any resulting advantage from the resemblance as a proof that the resemblance is not the result of natural selection. Chapter xiii. of part v. treats of the enemies of spiders, and their influence on habit. This subject is, of course, closely connected with protective resemblance; and by no means the least interesting part of this chapter is the account of some truly parasitic spiders-Mimetus interfector and others. These take up their abode in the webs of other spiders, and after eating the rightful owner, regale themselves at leisure upon its eggs and young. Part v. ends with chapter xiv., on Death and its Disguises; Hibernation, and Death feigning." Natural death may be almost said to be an unnatural event in the history of most of the creation, excepting man ; but perhaps more frequent instances of it are seen by the entomologist and araneologist, than by other naturalists. Some of our British Drassidæ, in the genus Clubiona for instance, may often be found sewn up in a nest of leaves drawn together, with their egg-sac, brooding over it, in various stages of lethargy, sometimes so shrivelled and comatose as to be almost incapable of movement. These spiders probably drop to the earth with the opening of the nest for the exit of the young, and at once die when their progeny begin to live. The author gives interesting details of a similar kind in reference to spiders of the family Epeirida far removed from the Drasside, and we have also noted it in another family equally remote from both, Thomisidæ. "Death feigning" is considered to be perfectly voluntary, though perhaps developed out of an original state of "fright-paralysis"; contrary to the opinion and explanation given by Darwin of this habit. The concluding part of the book, part vi., contains an account of fossil spiders, a subject which, though bearing very little upon the 'spinning work of spiders," has a very strong and an increasing interest of its own. It appears to be well treated in the twenty-three pages here devoted to it. We cannot leave this necessarily very incomplete notice of Dr. habits of the spider, it would seem to be well enough accounted for as the result of excess of vigour or vital force belonging to the stronger or male sex. The action of natural selection would operate here also, indirectly, and these and other similarly excessive developments would only be checked when they tended to become, or became (as in some cases they indeed appear to have nearly become), positively detrimental, or at any rate disadvantageous, to the sex. The senses of spiders-" smell,” “hearing," and "touch"-are then gone into. In connection with the sense of "hearing," various stock stories about spiders and the effect of musical sounds upon them are detailed; but such small credit is attached to them as relating facts on which any scientific conclusions can be based, that it would hardly seem to have been worth while to swell an already bulky volume by their repetition. Chapter x. of part iv. ends with the details of the stridulating power of some spiders and its probable purpose. Chapter xi., on the colour, and colour-sense, brings part iv. to a conclusion. The more brilliant colouring and ornamentation of the male spider, in some groups, is accounted for by the preference supposed to be given on the part of the female to males thus ornamented. But it does not appear that this preference is yet proved in any instance as a fact; nor can it be fairly argued that, because sexual excitement often leads the male to display it in curious antics and contortions, it therefore follows that the female is in the least influenced by it; whereas in fact, as she is stated to be (p. 63), the female is generally an unmoved spectator. Doubtless the male frequently succeeds in his purpose after such displays-post hoc certainly, sed non propter hoc. The author having come to the conclusion that the female prefers the male for his bright colours, we are not surprised to find it argued, conversely, that in those groups where it is the female sex which is the largest and bears the brightest hues, it is the less gaudy male who is helped and influenced in his choice by the increased size and excessive coloration of the female. The argument here also does not appear to have more real weight than in the former case, if even so much. On the subject of adaptation of the colouring of spiders to their surroundings and its beneficial effect, the opinion is expressed that, considering the great exposure to enemies of numbers of brilliantly coloured and conspicuous spiders, no generalization is yet warranted. No weight seems here to be given to the supposition that some of these exposed spiders may be distasteful as food; | McCook's bulky volume without drawing especial attenwhile it is admitted that many, as those of the genera Gasteracantha and Acrosoma, are protected by their spiny armature, and, it may be added, by their generally hard integument. The theory of "warning colours" is dismissed as inapplicable to spiders. Adopting the experiments of Sir John Lubbock and Mr. and Mrs. Peckham, spiders are considered to possess a sense of colour; but when we are told that a test case was afforded by a spider whose eyes had been purposely MR. BASSET'S ELEMENTARY TREATISE ON blinded with paraffin, our confidence in the result of these experiments will perhaps be a little shaken; since it is gravely argued from this test case that, because a blind spider exercised no apparent choice of one colour over another, this proves that the apparent preference of a spider before blinding was a true choice, and that there exists a colour-sense in certain spiders. Chapter tion to the numerous (401) woodcuts, and the coloured HYDRODYNAMICS AND SOUND. An Elementary Treatise on Hydrodynamics and Sound. WHEN WHEN the Senate of the University of Cambridge decided to adopt the suggestion of the Special Board for Mathematics to include the elements of hydro dynamics and the theory of sound among the subjects of Part I. of the Tripos, teachers of these subjects naturally looked to Mr. Basset to provide a text-book that should meet the wants of students preparing for the examination, and he has responded to the demand with great promptitude. The present treatise is designed, he tells us, for those who are reading for this examination and others in which a knowledge of these subjects is required. If the purpose of the book had been different-if, for instance, it had been written as a purely scientific training for hydraulic engineers, or for use in a physical laboratory -it would have had to be conceived in a very different vein. We should have looked for full explanations of elementary concepts, frequent appeals to experiment, constant arithmetical interpretation of the analysis, and a large proportion of physical reasoning. If, however, the book is to be judged by the standard it aims at, it must be regarded as an admirable specimen of an examination book. The propositions are clearly set out in a methodical order. They are isolated from each other as much as possible, and proved individually by the use of appropriate principles. The examples are for the most part | well chosen, and calculated to initiate the student into a great variety of the tips and dodges with which the examiners are likely to be familiar; and no more is generally given than would be useful in writing out bookwork and solving problems. We proceed to a detailed account of the work. The treatise is divided into two parts, of which the first deals with hydrodynamics, and the second with the theory of sound. In the first part there are five chapters. Chapter i. treats of the kinematics of fluids and of the general equations of motion. We are glad to see that the author has given prominence to the "flux method," and has had the courage to restore the elementary parallelepiped which Prof. Greenhill affects to despise; for the purposes of an elementary treatise the value of this artifice is too great to be lost. Very welcome also is the proof of the important principle at the foot of p. 11, first stated exactly in the larger treatise, vol. ii. p. 234, and apparently due to Prof. Greenhill ("Encyc. Brit.,” Art. "Hydromechanics"). We could wish that the theory of the bounding surface had been as fully explained. The same chapter i. contains a short account of sources, doublets, and images, and electric and magnetic analogies are given which add much to the usefulness of these sections. Chapter ii. treats of the motion of a sphere and of the motion of certain cylinders in an infinite fluid. The descent of the sphere under gravity is very nicely worked out, the usual ambiguity being avoided by explicitly introducing the distance of the centre from a fixed horizontal plane. The resultant pressure on the sphere is calculated, and the equations of motion deduced from Newton's second law. The chapter concludes with an interesting account of the resistance of a liquid to the motion of a spherical pendulum. This chapter contains an exception to the general plan of the work. Mr. Basset appears to write hydrodynamics con amore, and cannot always be restrained from trying to teach the student something which he will not be called upon to write out. We refer to his account of recent researches in the theory of the resistance of viscous fluids. Chapter iii. is occupied with the theory of the motion of a single solid in an infinite liquid. This part of the subject is less elementary than the others which are treated in the book, inasmuch as the machinery of moving axes has to be introduced. The author has cleverly avoided the use of Lagrange's equations and Routh's method of ignoration of co-ordinates, but it must be confessed that it is sometimes a little difficult to see how some of the terms in the equations are obtained by means of the principles invoked. The student may well be puzzled to account for the term - M'g in the equation of motion of the sphere on p. 69. The most interesting problem discussed in the chapter is that of the motion of an elliptic cylinder. Drawings of the path of the centre of gravity in the three cases of oscillation, revolution, and just complete revolution, are given. In the first case, the path looks something like an orthogonal projection of a curve of sines, and the cylinder moves so as to have turned through the maximum angle when the centre is at an inflexion; it then turns back, and the angle described goes through a periodic oscillation while the cylinder moves over a wave-length. In the second case, the path looks like a nodal trochoid, and the cylinder makes one complete revolution in the time taken to pass from a node to the next consecutive node but one. In the third case, the path looks like a nodal cubic with an inflexion at infinity. The cylinder moves from infinity with its major axis initially parallel to the asymptote; at the furthest extremity of the loop it has turned through a right angle, and it then goes off to infinity in the opposite direction, and only turns through two right angles in the whole length of its path. Other interesting things in the chapter are the application of the theory of helicoidal steady motion to explain the necessity of rifling guns, and the theory of the motion of a cylinder in a fluid bounded by a fixed rigid plane, leading to the suggestion of the realization of “action at a distance" by means of fluid pressure. 17 Chapter iv. is devoted to liquid waves. All the elementary problems are treated very elegantly. Long waves are in the first place regarded as a particular case of progressive harmonic waves, and the "exact theory" of long waves in a canal comes afterwards. This seems to us the most natural order. Another point of interest is the discussion of a case of instability, due to Lord Rayleigh. Mr. Basset has done well all through to insist upon the importance of investigations relating to stability. Chapter v. is occupied with the theory of rectilinear vortices. The vortex line is treated as an ideal limit of a vortex cylinder, and some cases in which the cylinder is of finite section are discussed. We think it unfortunate that in treating the elliptic vortex cylinder the value of the constant D is not given, as it is directly proportional to the circulation; but the student reading the section is certain to take it to be an arbitrary constant. The simplest cases of motion of a straight vortex in a bounded space are treated by the method of images. The chapter concludes with new proofs of Helmholtz's celebrated "laws of vortex motion." A brief account of Sir W. Thomson's theory of " vortex atoms" would have been of interest here. Part ii. of the treatise deals with the theory of sound, and contains five chapters. The first of these (chapter vi.) is intoductory, and explains the relation of musical notes to the vibrations of bodies, and the connection be tween sound and the propagation of waves in air. It is admirable rather for conciseness than for completeness of exposition. Chapter vii. is occupied with the vibrations of strings and membranes, nearly the whole of it being devoted to transverse vibrations of strings. The method of acoustics is adopted, as developed in Lord Rayleigh's treatise. It consists in assuming the motion to be periodic, and dependent upon a function called a normal function, in a series of which arbitrary functions can be expanded. Mr. Basset has changed the nomenclature, so that the "normal co-ordinate" of Lord Rayleigh is here called a "normal function." Is this intentional ? The method adopted dispenses with the necessity of proving Fourier's theorem. Other things in this chapter worthy of note are the formation and discussion of the equation of motion for a string subject to viscous resistance and under the action of a periodic force, leading to a particular illustration of the well-known theory of forced vibrations. Chapter viii. is occupied with the theory of the vibrations of bars. It opens with an account of the stress in a bent bar, and we have here the first hint in an English book on acoustics of any difficulty in that subject. In a footnote Mr. Basset clearly states the nature of the assumption usually made, and further expresses his conviction that it is not rigorously true, describing the character of the change in the equations of motion if a more exact theory were adopted. It is a good thing to have mentioned this. The rest of the chapter is devoted to the lateral vibrations of bars. The differential equations are obtained by the use of the stress equations, the idea of the method of formation being taken from a paper by Dr. Besant, and the frequency equations are given for the various cases of ends supported in different manners. Although, perhaps, a discussion of them may be beyond the purpose of the book, we cannot help thinking that a few numerical results would assist in the comprehension of the subject The two last chapters deal with the theory of waves in air. Chapter ix. contains the formation of the differential equation of vibrations, and a discussion of the value of the velocity of sound as given by Newton and Laplace's suppositions respectively. To explain the latter an account is given of the thermodynamics of gases, leading to the relation of pressure to density when the changes are isentropic. Chapter x. contains an account of some of the simpler problems of plane and spherical waves. We find here the theory of the notes in a doubly closed pipe, and a short discussion of the forced vibrations produced by attributing an arbitrary periodic motion to a disk at one end of the pipe. The interest of vibrations in pipes lies rather, as it seems to us, in the cases where the pipe has one or both ends open. Even when these are treated as "loops," something may be done towards a theory of organ pipes. The relation of the notes in a "stopped" to those in an "open" pipe is not even given as an example, nor do we find any account of the interesting problem of reflexion of waves in a pipe at the stopped or open ends. The next subject treated is the reflexion and refraction of plane waves at a surface of separation between two gases; this is very nicely worked out, the equations and conditions being very clearly given. The rest of the chapter is occupied with spherical waves. We have here Lord Rayleigh's solutions for (1) purely radial disturbance within a rigid spherical envelope; (2) the vibrations in a conical pipe; (3) the resistance of the air to the motion of an oscillating sphere, and the theory of the scattering of plane waves by a small sphere. The last problem, as here solved, requires the expansion of the velocity potential in a series of spherical harmonics -the only instance in the book of the use of these functions. The book is well printed and nicely bound. The few blemishes we have had occasion to notice will not seriously diminish its value, and Mr. Basset is to be congratulated on having produced a work that certainly A. E. H. L. ought to achieve success. LOWNE ON THE BLOW-FLY. Anatomy, Physiology, Morphology, and Development of the Blow-fly (Calliphora erythrocephala). Part I. By B. Thompson Lowne, F.R.C.S., F.L.S., &c. (London : R. H. Porter, 1890.) MF R. LOWNE'S new work on the blow-fly, of which Part I. has just appeared, requires the serious attention of all who occupy themselves with insect anatomy. It contains the results of a diligent and protracted inquiry, and will teach even specialists a good deal which they did not know before. Mr. Lowne has written before on this subject. His earlier book (1870) on the blow-fly was the manual of what we may now call a past generation of insect-anatomists, who studied it zealously, and, we fear, often got hopelessly puzzled with its many difficult passages. The present publication is not a new edition, but a totally new work, and the author has only thought it worth while to mention his earlier memoir quite casually in one or two places. The interval of twenty years has enabled Mr. Lowne to make great advances in the knowledge of his subject, and his old treatise on the blow-fly may now cease to be read. This increase of knowledge is due to laborious microscopic investigation, and to a lengthy, though not exhaustive, study of a literature which is copious, technical, and very largely German. The student has to thank the painstaking author for many new facts, and also for a good deal of information, which, though not new, was previously accessible only to specialists. Perhaps the most interesting remarks which we have found in Part I. relate to the imaginal disks (it would be better to call them imaginal folds), those curious inward growths of the larval epidermis from which nearly the whole body of the fly is ultimately fashioned. Mr. Lowne's account should be carefully examined by those who have hitherto been content with text-book information, or the descriptions of Weismann, which, original and brilliant as they were, required rectification on a number of special points. We can look forward to a discussion of these imaginal folds far more interesting, and at the same time simpler, than any that present knowledge has produced. Such a type as Corethra (which, by the way, is misquoted as Chironomus in the note to p. 77) shows a slight telescoping of the imaginal antenna within the larval head. Other types, as yet imperfectly described, exhibit deeper and more complex invaginations, while the Muscidæ form the extreme term of the series. At this moment we want above all comparative studies, and till they are supplied, minute descriptions of highly special cases are hardly intelligible. Few biologists seem to be aware of the interesting research which lies open to any competent student in a well-selected series of Dipterous larvæ and pupæ. It will ultimately be necessary to include other insectorders, for imaginal folds are not peculiar to Diptera. Many Lepidoptera are instructive in this connection. Pieris, for example, as J. Dewitz (Biol. Centralblatt, Bd. iii. p. 582) points out, exhibits that connection between the sutures of the clypeus and the antennary folds which the author (quoting Mr. Hammond) has noticed on p. 43. The subject is not sufficiently worked out for popular treatment, and the beginner who takes up Mr. Lowne's account of the development of the fly has many a hard nut to crack. The new work contains many interesting particulars concerning the life-history and minute structure of the blow-fly; there are not a few useful figures, and the bibliographical references are tolerably extensive. If the succeeding parts are equally full of matter, the treatise will make a really considerable addition to our knowledge. Nevertheless there are some faults to be pointed out. The arrangement of the matter is not always convenient or luminous; see, for example, the place (p. 12) chosen for the definition of an insect and the definition of morphology. Now and then an ill-considered remark, perhaps having no close connection with the subject in hand, distracts or misleads the reader. Why should the author go out of his way to speak of mammals, birds, and reptiles as "separate and divergent genetic series" (p. 26), a proposition by no means so evident that it can be thrown in as a passing illustration! Surely Mr. Lowne, by thinking twice, would have saved his readers from puzzling over that strange remark (p. 7) that in all insects (this is apparently the sense) there is no cœlom or "distinct continuous body-cavity." We shall await with much curiosity the promised proof of the hepatic function of the Malpighian tubules. Meanwhile we can only wonder in what sense the author uses the word hepatic. We shall also be glad to learn the reasons for believing in a metenteron," as defined on p. 17. No one interested in insect anatomy is likely to adopt all Mr. Lowne's views, but no such person can hesitate to admit that he offers us a substantial contribution to his favourite subject. OUR BOOK SHELF. L. C. M. A Treatise on the Diseases of the Sheep; being a Manual of Ovine Pathology especially adapted for the use of Veterinary Practitioners and Students. By John Henry Steel. (London and New York: Longmans, Green, and Co., 1890.) SHEEP and their diseases have had but little attention from the veterinary profession, and consequently this work, just published by Mr. J. H. Steel, one of the most astute and successful veterinary practitioners and teachers of the present day, must be looked upon as the result of an important step in the right direction. Though we admit the author's ability and the probable usefulness of the book, yet the most conspicuous feature connected with it is the evidence which it gives of how very little of a sound, practical, and useful nature is known by scientific men in relation to sheep. No claim is made to originality in the subject-matter produced, and indebtedness to the various authorities quoted is freely acknowledged. There is, however, a distinct want of discrimination between those who are the leading authorities on certain subjects and those who are not. One who could write the three names, Walley, Williams, and Gamgee, in the order presented, shows he has no regard for precedence in virtue of merit. Gamgee in his day was perhaps the greatest genius who had ever adorned the veterinary profession, and Williams is unquestionably the most successful living extraordinary kind appear where the writer, who is not author of veterinary works of a high order. Errors of an himself familiar with the subject, attempts to enlarge upon the statements of others from whom he quotes; for example, in writing of the tick, ked, or fag (Melophagus ovinus), he says "the animal buries its head and proboscis nimble and active, and sometimes as large as a horsein the skin, and once fixed hangs on for months. It is bean." Any entomologist familiar with sheep cannot fail to see that the author has mistaken the grass-tick (Ixodes) for the sheep-tick (Melophagus), which belongs to a different genus, and has confounded the habits of the two creatures in an extraordinary manner. Apart from errors of this kind the work is far from complete, but if due care were taken to correct mistakes and to consult as additional references such recent works of a superior kind as "The Animal Parasites of Sheep," by Dr. Cooper Curtice, published at Washington by the United States Government during the present year, the second edition might be made a most serviceable, interesting, and valuable volume. Wild Beasts and their Ways. By Sir Samuel W. Baker, F.R.S. Two Vols. (London: Macmillan and Co., 1890.) No one who has read any of Sir Samuel Baker's books of travel will need to be told that he has all the instincts and aptitudes which, under favourable conditions, make a man an eminent sportsman. He is, however, much more than a sportsman; as he himself says, he has never hunted without a keen sense of enjoyment in studying the habits of the animals pursued. In the present work he records some of the experiences he has had in various parts of the world, and students of natural history will find in his narrative much that cannot fail to interest them. The book is not, of course, in the strictest sense scientific; but it has points of contact with science, and these will make it as welcome to zoologists as it is sure to be, for other reasons, to general readers. Sir Samuel confines himself to wild animals which he himself has had opportunities of watching, so that all the incidents and and vividness which can belong only to descriptions that scenes he brings before us have that kind of freshness embody the results of direct personal observation. The work is admirably illustrated by reproductions of drawings prepared by Mr. Dixon. Properties of Matter. By P. G. Tait. Second Edition. (London: Adam and Charles Black, 1890.) THIS is a revised and considerably extended edition, and the author has paid special attention to points in connection with which difficulties had been found. Among the more important additions are the results of some of M. Amagat's splendid and hitherto unpublished work relating to the compression of liquids exposed to enormous pressures. This in itself, when completed, will, as the author remarks, "form a singularly interesting and practically new branch of the subject." |