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BOOK REVIEWS. Psychologie im Umrissen auf Grundlage der Erfahrung. Von Dr. HARALD HÖFFDING. Tr. from the Danish by F. BENDIXEN. Leipzig. Essai de Psychologie Generale. Par CHARLES RICHET. Paris, Bibliotheque de Philosophie Contemporaine.

FEW philosophical reformations have a more instructive history than that which introduced experimental methods and scientific conceptions into the study of mental phenomena. The cleft between the student of matter and the student of mind had no existence in the harmonious mental culture of Greek philosophers. The nature that is the common storehouse of the physicist, the physiologist, and the physician, was also the mine from which the philosopher drew his lore. The great modern revival that separates the sciences, and forces a medical congress to separate into nineteen sections to insure that he who reads will be understood, has left the philosopher in the high altitudes of the mountain-top, while the busy scientists throng down into the mine. Not until our day has the philosopher taken much interest in the carloads of rich ore dug out by the miners, and come to seriously consider the announcement that this patient digging had discovered many rich veins of thought suggesting those unifying generalizations for which he was searching in the clouds. The good effects of this change of method and re-arranging of interest are easily discerned. The 'know thyself' has been interpreted as including the whole man, body and mind, past and present, as modified by all kinds of natural and artificial agencies. But the most distinctly new contribution that this revival of nature-philosophy has brought about is the origination of a scientific psychology, borrowing its methods as well as many of its facts and conceptions from other sciences, and so re-uniting what should belong together, — while maintaining its distinct character by the use to which it puts this material, and the point of view from which it regards it.

The two volumes before us are both typical results of the new psychology. The one comes from the professor of philosophy in the University of Copenhagen; the other, from a professional physiologist of Paris. Their purpose is to set forth in plain language the conclusions which experimental research and observation have allowed us to draw regarding the nature and function of psychical phenomena, and to delineate the general conceptions to which these facts give warrant. As text-books, both will be eminently useful, and an English version of either would be a welcome contribution to our literature. The point at which the works divide is that the one is written especially for those in whose minds the philosophical interest is uppermost, while the other appeals more directly to the physiologist.

Professor Höffding, while seeing in objective research the central method of psychology, fully recognizes in self-consciousness a most important supplementary means of study. Not only that we can only make our own what we assimilate to our past selves, the deposit of a host of conscious acts, — but also that the higher mental processes are amenable to no other mode of study. On the other hand, he recognizes in consciousness a somewhat subordinate concomitant of certain psychical acts, and regards with equal interest such acts as have not this accessory; moreover, he holds that the latter can alone determine what is the naturally' correct mode of viewing the former. The author thus sees growing around the central 'natural' view of man several psychologies, a physiological psychology, a psychophysics, a comparative psychology, a sociological psychology. He does not attempt a strict definition of his science, and is more anxious that it should receive the benefit of a number of lights reflected from several quarters than that it should stand out as a distinct, self-made, smoothly finished speci

men.

The experimental basis' on which this psychology rests, includes quite as much such every-day facts as are made interesting by the tact of a humane observer, as rows of formidable tables fresh from the laboratory. The criticism passed upon Wundt's Physiological Psychology,' that it is simply a physiology with a psychology attached, would not be applicable here. Professor Höffding makes the physiology distinctly subordinate to the psychology, 1 M. Richet is also editor of the Revue Scientifique.

while constantly utilizing the facts that physiologists have discovered. For the non-technical student this is perhaps the better plan it retains for psychology that general broadening interest which its pursuit as a technical specialty may for a time weaken. The plan of the work is somewhat different from those of our textbooks of psychology, and is an improvement upon them. After defining his point of view, he considers the relations between body and mind as well from the physiological as the philosophical point of view, and passes to the study of the conscious and the unconscious, treating the phenomena of instinct, unconscious cerebration, etc. Here, as elsewhere, his acceptance of the evolutionary theory, and his use of the analogy between the growth of the individual and that of the race, give life to his pages. He next accepts the trifold division of the intellect, the feelings, and the will, though accenting the fact that each depends upon the other, and the development of all three follow the same path. His chapters upon the mutual relations of intellect, emotions, and will, are full of sound educational material. He devotes an unusual space to the emotions, while rather slighting the will. To single out any points for special treatment would hardly be serviceable: the important aspect of the volume is its modern appreciation of the intimate connection between fact and theory. Dr. Höffding has made a distinct advance in the problem of adopting new psychological results into the body of accepted truth, which serves to educate the next generation.

The main purpose of M. Richet's work is to give a useful summary of those general propositions regarding the functions of the nervous system that have a direct psychological bearing. In this he has succeeded very well, and his success makes us realize the progress made in recent years. It is a book of this nature that impresses one with the rapidity with which mental science is taking on that long-desired scientific aspect. It is no longer meaningless to speak of psychological laws.

What M. Richet means by 'general psychology' can be best gathered from the titles of his chapters. These treat of irritability, the nervous system, reflex action, instinct, consciousness, sensation, memory, ideation, will. Under each heading the treatment is general, stating in brief the conclusions accepted by modern psychology. Within two hundred pages one has here a convenient handbook of the main principles on which an elementary course in psychology should be based.

There is one point in the volume which M. Richet has singled out for separate treatment elsewhere, and which should be noticed here. Between an ordinary reflex action and a conscious act, the author introduces a 'psychic reflex,' and by this he means all those involuntary acts which have become so by interposition of conscious, inferential elements. The dog that trembles when his master shakes a stick at him; the man who feels nausea while reading of a disaster; the vertigo experienced when looking down from a height; many kinds of laughter, as of tears, fear, pain, and pleasure, are likewise psychic reflexes. These actions all take place involuntarily, but they would not happen if a psychic element did not intervene. Disgust would not occur if the tale were written in an unknown tongue. A psychic reflex is a response to a peripheral irritation insignificant in itself, but so transformed by an act of the mind as to put in operation the reflex centres of the spinal cord. This distinction is a convenient one, and the term will doubtless be adopted.

Ancient Nahuatl Poetry. By DANIEL G. BRINTON. Philadelphia, The Author. 8°.

THE recent volume of the author's valuable Library of Aboriginal American Literature, the seventh of this series, contains a number of ancient Mexican poems with translation, notes, a brief vocabulary, and an introduction. The poems are from a manuscript volume in the library of the University of Mexico, entitled 'Cantares de los Mexicanos y otros opusculos,' and printed from a copy made by Abbé Brasseur de Bourbourg. It is unfortunate that the author has not been able to have the texts collated with the original, but his efforts in this direction were unsuccessful: therefore it is probable that some corrections will have to be made in the texts. But scientists will nevertheless be thankful to Dr. Brinton for the publication of the interesting collection of poems

which are here for the first time made accessible to the student, and it is to be hoped that all that is extant of ancient Nahuatl literature will be printed ere long.

The texts are preceded by a brief introduction, in which the character of Mexican poetry is discussed. The importance of poetry, music, and dance among the Mexicans is set forth, and their method of delivering the songs is described. Of particular interest are the remarks of the author on prosody; and these are the more weighty, as he has studied this subject among many North American tribes. It is very difficult to decide whether accent or quantity is the ruling element of poetry, and the author does not attempt to decide which is more important. It seems to us that this question can only be solved by studying music and poetry jointly.

Dr. Brinton finds another wide-spread peculiarity of Indian poetry occurring in Mexican poetry. It is the inordinate lengthening of vowels and reduplicating of syllables for the purpose of emphasis or of metre, and the insertion of meaningless interjections for the same purpose. It is an interesting question whether the accent in Mexican poetry is always on the vowel, or whether certain combinations of consonants can form a syllable, as is the case in some American languages. The instrumental accompaniment of the songs is described, and the connection of the rhythm of the drums with the prosody is emphasized. In the present collection, as well as in those of other nations, we find a peculiar poetical language which makes their translation very difficult. Dr. Brinton describes this poetic dialect as abounding in metaphors. Birds, flowers, precious stones, and brilliant objects are constantly introduced in a figurative sense, often to the point of obscuring the meaning of the sentence. The grammatical structure is more complicated and elaborate than in ordinary prose writing, and rare words occur frequently. The rhetorical figure known as aposiopesis, when a sentence is left unfinished and in an interjectional condition, in consequence of some emotion of mind, is not rare, and adds to the obscurity of the wording. The last peculiarity is characteristic of the popular songs of all nations, while the occurrence of rare words may be due to the fact that many of them are sacred songs. The richness of metaphor, and the complicated grammatical structure, are also wide-spread qualities of poetry.

Dr. Brinton considers some of the songs as belonging to a time anterior to the Conquest, and gives in the brief notes which accompany each of the twenty-seven songs his reasons for this opinion. Undoubtedly most of them belong to the time of about 1500. Others are evidently ancient songs, composed before the Spaniards influenced the native customs and ideas, and this makes the present collection the more interesting. It is welcome material for the student of the Mexican aborigines.

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THE author terms his book very properly 'a sketch.' It is the tale of his journeys in Guatemala, adorned with some remarks on the geography and history of the country. The author does not claim to give any new information, but it is pleasant to follow him on his ride through a semi-civilized country. The book is profusely illustrated, and the illustrations have the merit of being new, characteristic, and trustworthy, most of them being reproductions of photographs. The scientific contents are selected somewhat at random, but will serve the purpose which the author has principally in view," to awaken among Americans greater interest in the much-neglected regions between the Republic of Mexico and the Isthmus of Darien." There are several maps in the volume, but they are of no great value. The map of Guatemala, which is claimed to have been compiled from various sources, is only a very rough sketch of that country. By far the greatest portion of the book is taken up by the author's journeys; and this is the most interesting part, as it gives a fair idea of Central American life, and valuable hints to future travellers. It is followed by a chapter on the ancient inhabitants of Guatemala, a brief history of the Republic, and a sketch of its volcanoes and produce. In an appendix, which the author compares to the attic-room of a thrifty housewife, information about a variety of subjects and a partial bibliography of Central America are given.

The Principles of Elocution. By ALEXANDer Melville Bell. 5th ed., revised and enlarged. Washington, John C. Parker. 12°.

VERY many intelligent readers of the great orators, ancient and modern, must have experienced a feeling of keen regret that they themselves were unable even to approximate the directness, force, and fluency of those masters of the art of expression. It would almost seem that the power to rouse multitudes to action, to stir the deepest and most masterful emotions, to control and direct action, by the use of language, is so dangerous a one that it has been granted to but few. As a matter of fact, however, oratory or eloquence is nothing more than highly developed and cultivated power of expression. It implies the possession of something to express. The full head and the sympathetic heart are essentials.

But without aiming at the ambitious height of eloquence, there is a power of forceful and adequate expression by the use of language that belongs to us as human beings, but which is almost wholly overlooked in the training of the young. Not only is this undesirable in itself, but the conditions of our modern life render it more so. In politics, in religion, in practical life, and in social activity, men are endeavoring to communicate their own thoughts and convictions to others; and very many are the embarrassments that result from the lack of ability to properly express these thoughts and convictions. There is, therefore, a practical as well as a sentimental reason why our natural gift of expression should be cultivated.

All of this is very familiar to Mr. Bell, and, in addition, he has given so much time and study to the working-out of the practical applications of the thing, that he is to-day easily our first authority on the subject. In this last edition, the fifth, of his 'Principles of Elocution,' he has given us the ripest fruits of his thoughts and study.

Mr. Bell deprecates in his introduction the neglect of elocution, and ascribes it to two causes, — first, it is neglected because it is misunderstood and therefore undervalued; and, second, it is misunderstood because it has been confounded with recitation, and otherwise misrepresented by many writers on the subject. Mr. Bell defines (p. 6) elocution as "the effective expression of thought and sentiment by speech, intonation, and gesture." Inasmuch as it involves the exercise of language, elocution must embrace the physiology of speech. It must study carefully the instrument of speech, so that the elocutionist may have all its parts under his complete control. The author therefore takes the pupil back to respiration as the first step toward making him an expressive and agreeable speaker. Suggestions in respiration lead naturally to the principles of vocalization, and these to those of vowel formation. From this point on, the book is made up largely of practical exercises on the successive steps in the elocutionary process. These exercises and illustrations are a peculiarly valuable feature of the book; for they are not roughly thrown together, but carefully arranged on scientific principles.

We know of no higher praise of Mr. Bell's book than to say that it is pre-eminently fitted to be recognized in our high schools and colleges as the authoritative exponent of that branch of training which has too long been left out of their curriculum.

Bau und Verrichtungen des Gehirns. Von Dr. JOSEF VICTOR BOHON. Heidelberg.

Uebersichtliche Zusammenstellung der Augenbewegungen, etc. By Dr. E. LANDOLT. Tr. by Dr. H. MAGNUS. Breslau. THESE Contributions to the anatomy and physiology of the nervous system are evidences of the time and attention now devoted by the Germans to the preparation of aids to instruction whereby the student can readily obtain correct notions of his subject. Especially in the nervous system, where recent research from a variety of sources has so essentially altered the accepted views, is such an elementary reconstruction of the subject necessary. Dr. Rohon's pamphlet contains a lecture delivered before the Anthropological Society of Munich, setting forth in clear language the main outlines of current notions of the structure and functions of the brain. The main interest in the pamphlet will centre in the colored chart, which illustrates with great clearness the points referred to in the

text.

Dr. Magnus presents a chart for the use of physicians and instructors, showing the main points with regard to the motion of the eyes that one ought to retain. The main laws of motion of Donders, Helmholtz, Listing, etc., are given; then a cut illustrating the origin of the motor nerves of the eye. This is followed by a table giving the origin, course, insertion, axis of rotation, etc., for each muscle of the eye. The second part of the chart explains very clearly the effect of paralysis of each of the muscles; how such paralysis limits motion of the eye; what position the eye assumes; whether double images arise, and how they are placed; and so on. The chart shows careful preparation, and will doubtless be widely used.

The Journal of Morphology. Ed. by C. O. WHITMAN, with the co-operation of EDWARD PHELPS ALLIS, Jun. Vol. I., No. 1. Sept., 1887. Boston, Ginn & Co. 8°.

THE new zoological periodical, the first number of which has been so long expected, has at last made its appearance in the shape of a thick and handsome volume of more than two hundred pages, issued from the well-known press of Messrs. Ginn & Co. of Boston. It has been delayed almost unpardonably long, and yet its makeup and the character of its contents compel us to forget the delay, and confess that it was well worth waiting for. The plates alone would make the journal unique among American periodicals devoted to the subject; for they are mostly from the hands of Werner and Winter, the Frankfort (Germany) lithographers, whose names alone are ample guaranty of excellence. In brief, the journal appears to us admirable in almost every particular. The paper is good; the press-work is well done; the minor details of arrangement of footnotes, titles, headings, etc., give evidence of care and forethought.

In this periodical we have a substantial token of the progress of two distinct undertakings of which all American scientists ought to be proud. The first is that of Dr. Whitman, the editor, whose hope and struggle for many months have been to set going in the right way a zoological periodical that shall worthily represent American morphologists before the world, and be a suitable outlet for our strong and increasing zoological literature. Professor Whitman has certainly succeeded in making a good start.

A word is due also to the publishers, Messrs. Ginn & Co., for their courage in undertaking such a periodical, which can never be expected to be a financial success, as the demand must always be extremely limited. The difficulty of establishing such a journal will be the better understood when we consider that the proceedings of societies, supported by large endowments, meet with practically no sale, but are distributed throughout the world by exchange, and furnish a very excellent means for the placing on record of such papers as are given in this magazine.

The other undertaking is that of Edward Phelps Allis, Jun., of Milwaukee, with whose co-operation the journal is edited by Dr. Whitman. Mr. Allis first formed, and then put into active operation, the idea of a private biological laboratory of research. For this he was fortunate to secure Dr. Whitman as director, and to it the name of the Lake Laboratory' has been given. Besides the director, Mr. Allis has added to his laboratory Dr. William Patten as assistant, and it is understood that Mr. Allis is himself at work upon important investigations.

NOTES AND NEWS.

IN September a school of Oriental languages was opened at Berlin, the object of which is to give merchants and civil officers an opportunity to learn the languages of Asia and Africa. The staff of the school consists of two teachers of the Arabian language, while Persian, Chinese, Suaheli, and Herero have one teacher each. These have studied the languages they teach in the country where it is spoken, and they are assisted by natives. This school will undoubtedly prove of great value to the commerce of Germany with the countries of Asia and Africa. The merchant or consular official who understands and speaks the language of the country in which he lives and works will have a great advantage over competitors who have to make use of the service of interpreters. Formerly students had the opportunity of studying Oriental languages at German universities, but there they were taught from an exclusively

scientific point of view; and it is well known that a language learned in this way, though its grammar may be well mastered, is of no practical value to the student, particularly where the difference between the written and spoken languages is great, and where the dialects are numerous. In the new school the languages are taught as living languages, and this gives the institute its principal importance.

- The semi-annual session of the National Academy of Sciences will be held at Columbia College, Nov. 8, at noon, and continue for three or four days.

The question of teaching physiology and hygiene to elementary classes in the public schools is one that is far from a successful solution. With a criminal rashness, legislatures have been induced to prescribe alcohol-teaching as a requirement, and the result has been to create noxious temperance-tracts with a smattering of physiology attached, instead of scientific text-books. A very great improvement in this direction is a recently issued primer of health lessons by Dr. Jerome Walker. Around the main facts of physiology, the author has woven an attractive text, fully and well illustrated, and has given the subject that kind of interest which healthy children appreciate. He has very much reduced the space usually allotted to alcohol and narcotics, but it may be questioned whether the reduction is sufficient. A few very objectionable passages (considering the age of the children to whom the book is addressed) still remain. On the whole, Dr. Walker has set an example in the right direction, and the instruction to teachers is not the least valuable chapter in the book.

One of the subjects discussed at the annual meeting of the French Association for the Advancement of Science, which has just been held at Toulouse, was the project for making a maritime canal between Bordeaux and Narbonne. The different phases of this project, which was first mooted twenty years ago, were passed in review by M. Wickersheimer, deputy for one of the departments through which the canal will pass. The latest project was prepared this summer by a company which has been formed for the purpose of making the preliminary survey; and according to this scheme, the canal, which would be about three hundred and thirty miles in length from sea to sea, would start from the western side of Bordeaux, and follow the left bank of the Garonne for a distance of fifty miles, crossing that river at Castel-Sarrasin by a pontcanal (or aqueduct), and follow the right bank of the river as far as Toulouse, where a large port would be created. From Toulouse to the Mediterranean seaboard at Narbonne, the maritime canal would be quite independent of the railway from Bordeaux to Cette, but it would twice cross the Canal du Midi. The curves of the canal would be of the same radius as those in the Suez Canal; that is to say, not less than 6,000 feet, and there would be 38 locks, the fall of which would range from 20 feet to 30 feet. The depth would be about 24 feet, but if the minister of marine should determine to make use of it for the first-class ironclads of the French navy, contrary to what was originally determined, the company will be prepared to make it three feet deeper. It is estimated that the mean speed of vessels passing through the canal will be seven miles an hour, and they would be drawn by locomotives running along a line of rails placed on the banks, a force of from 1,000 to 1,200 horse-power being required to produce this rate of speed. The canal is to be lighted by electricity, the electric light being generated upon the engines used for the traction of the vessels. The total cost is estimated at £130,000,000, or less than half of the estimate originally prepared. The distance saved for vessels coming from the western ports of France into the Mediterranean would be 680 miles.

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-It is noted in the Journal of the Society of Arts, London, that while the consumption of the other dietetic articles used for beverages -tea, coffee, and chiccory — show a decline last year, cocoa is marked by a considerable increase. This is remarkable, since for about four years, from 1875 to 1879, it remained pretty stationary at about 10,000,000 pounds, but after 1880 it began to make steady progress, advancing from 10,500,000 pounds in that year to over 15,000,000 pounds last year. Of powdered cocoa and chocolate England received 1,332,000 pounds, chiefly from Holland. She

also imported 3,211 hundredweight of husks and shells of the cocoabean, which are also used up for cheap cocoa. There are about ten chocolate and cocoa manufacturers in Holland, whose yearly requirements of cocoa-beans may be estimated at 3,000 tons, in round numbers, principally of Guayaquil, Caracas, and Domingo kinds. They mostly manufacture cocoa preparations, known by the name of soluble cocoa, cocoatine, and cocoa-powder; viz., the roasted and powdered cocoa-beans deprived of most of their natural fat, or the cocoa-butter, which is used as a valuable ingredient by manufacturers of chocolate and cocoa sweetmeats, and also for pharmaceutical preparations. In the early part of last month no less than twenty-five tons of this cocoa-butter was sold in Holland, and fifty tons in London. The oldest of the Dutch cocoa-works was founded on a small scale more than a century ago, and most of the other works have existed from forty to sixty years; but all of them remained insignificant until the before-mentioned powdered preparations found their way to foreign countries, especially England and Germany, where certain Dutch brands of powdered cocoa have been very well received and enjoy a large sale. There are people who suppose that the superiority of the Dutch cocoa-powder is to be attributed to a peculiar mode of manufacture, different from the methods followed in other countries. The idea to extract the fat from the roasted cocoa-beans, and to sell the powder, is said to have originated in the brain of a Dutch chocolate-maker about 1830. It is now generally practised in France and England. The average consumption in the United Kingdom last year, per head of the population, was, of cocoa, 0.41 pounds; coffee, 0.86; tea, 4.87. Tea brings into the revenue £4,500; coffee, only £200,000; and coffee mixtures and chiccory, £5,273. The latter seem to be declining.

LETTERS TO THE EDITOR.

"The attention of scientific men is called to the advantages of the correspondence columns of SCIENCE for placing promptly on record brief preliminary notices of their investigations. Twenty copies of the number containing his communication will be furnished free to any correspondent on request.

The editor will be glad to publish any queries consonant with the character of the journal.

Correspondents are requested to be as brief as possible. The writer's name is in all cases required as proof of good faith.

Recent Methods in the Study of Bryozoa.

IN Science for Oct. 7. Prof. Joseph F. James refers to certain new methods in the study of Bryozoa, and doubts their efficacy in classification; he also refers to a forthcoming publication which shall make this clear. Pending the publication of this paper by my esteemed friend, I cannot help expressing my decided approval of the methods he calls in question. Theoretically, development has proceeded in two lines, one internal, to accommodate itself to the needs of internal function; and one external, to accommodate itself to environment, to the world with which the being comes in contact. Variations of function are far less frequent than those of environment: hence internal structure may still be very similar when external features have already extensively varied. Hence internal structure usually furnishes the reliable characters, which distinguish genera and higher groups; external features are used for specific determination.

Very few who have practically attempted the classification of paleozoic Bryozoa into genera as defined according to the old method have failed to see that such genera contained heterogeneous assemblages of forms, often ran into each other, and contained no distinct positive characters which were useful when great numbers of Bryozoa were to be classified. The new method has furnished solidity to this structure. The species fall into easily recognized groups, as distinct as those of other organisms on the same scale of development; all this simply because of the abandonment of external characteristics in the distinguishing of genera, for those of an internal nature, made easily accessible by the slide and the microscope. In this department of study, Prof. H. A. Nicholson took the first decided stand, and is still contributing at short intervals valuable papers on this interesting group of fossils; but I believe that to one of our fellow-countrymen, Mr. E. O. Ulrich, belongs the credit of the perfection of this system. His work, which expresses his matured views on this subject, is now in the press, forming a part of Vol. VIII. of the forthcoming Illinois Report.' By his kindness

I have been permitted to see plates, and furnished with private extracts from the same, and I feel free to say that it will be a monumental work in history of the study of Bryozoa.

The practical test of the theory of development, which holds good everywhere else in animated nature, is also satisfactory here. Instead of artificial we have natural classification, and that also of a more definite and practical form. It remains to be seen whether microscopic sections are sufficient to determine the species. A circumstance peculiar to Bryozoa makes this in almost all cases possible. The form, size, and arrangement of cells may be readily seen in tangential section; the presence of interstitial cells may also be thus discovered; whereas the little elevations or low spines around the apertures of some cells may be seen in the sections as spiniform tubuli. Elevated patches of cells may usually be recognized by the local increased size of cells in the sections, and maculæ will be shown by judicious longitudinal sections.

It remains to be seen what characters of specific importance cannot be shown in microscopic sections. One of these is the size of the specimen; another, its method of branching; a third, its general contour. These may all be expressed by a simple drawing, taking no cognizance of individual cells. Besides the details above referred to, microscopic slides will of course furnish numerous others referring to internal structure alone. The fact, however, is, that not only do microscopic slides reveal the characteristic features of the surface, but they often reveal them in a much better way than the specimens at hand; for these may be abraded, perhaps ever so little, but just enough to rub away the little spines, or to remove the walls of interstitial cells, and, by thus exposing the diaphragms of the same, lead to the conclusion that they do not exist. Any one who has ever looked over a quart-measure of specimens without finding one suitable for description will know what this means.

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As regards the publication of Mr. Foord, Contributions to the Micro-Paleontology of the Cambro-Silurian Rocks of Canada,' it is an excellent exemplification of the methods (for this is what Professor James criticises) of the advanced school of students of the Bryozoa, and is a practical recognition of the merits of a work done by an American paleontologist. All of the species figured are accompanied by magnified sections of the same, and all except Monticulipora Westoni have also figures of the specimen's natural size; and perhaps the shape of that species, "Zoarium irregularly hemispherical," would not be difficult to grasp by the working paleontologist. The fact that Prof. H. A. Nicholson, immediately after the separation of Mr. Foord from the Geological Survey of Canada, was pleased to publish papers conjointly with that gentleman, serves to show what that eminent authority's opinion as to the merits of Mr. Foord's specific work was.

These remarks I hope represent fairly the claims of the new school as to the advantages of their methods of study. One observation alone remains to be made. I suppose that Professor James was not in earnest when he objected to the new method on account of the difficulty of making slides, no more than the physicist who should object to the advance made in his science simply on account of some of the refined mechanisms now used in his department, no more than the student of Entomostraca who should object to the classification reached in his science from the difficulty in finding a specimen which is willing to be quiet enough to let itself be accurately drawn. He simply expresses the difficulty he finds in leaving his old methods of study and adapting himself to new ones, and this accidentally escaped into print, not in the form in which he would be willing to have it remain at second thought. But the truth is, that microscopic slides are not difficult to make. Messrs. W. F. and John Barnes of Rockford, Ill., manufacture an instrument which I know from experience to be both cheap and useful. The specimen to be cut is ground with emery until a plane is formed having the same direction as the intended section. Then successively finer grades of emery are used until a fine polish is obtained, which can be made very fine indeed by using polishingpowder sprinkled over a piece of plate glass. Then the specimen is carefully washed, dried, and glued with Canada balsam to the slide which is to retain the specimen. Then the specimen is ground away until only a thin sheet remains fastened in the Canada balsam, after which it is again smoothed, washed, and protected by a thin cover-glass. Forty to sixty slides can be made in a day.

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Search for Gems and Precious Stones.

IN reference to the interesting article of Prof. P. L. Simmonds on the search for gems and precious stones, read before the Society of Arts of England recently, reprinted in your issue of Oct. 14, allow me to suggest a few corrections. Professor Simmonds estimates the yield of the Brazilian diamond-mines at £800,000 annually, while a little later on he says that the yield has dwindled to 24,000 carats, which at the outside will not yield more than £2 to £3 a carat, and that of India, Borneo, and Australia at £200,000, when these latter figures would probably cover the annual product of Brazil as well as that of the other three countries named. Australia produces so very little as scarcely to be a factor in the computation. Even before the opening of the African mines, in 1867, the estimated value of the product of Brazil from 1861 to 1867 was only £1,888,000, or something over £300,000 per annum, at a time when Brazilian diamonds commanded a higher price than at present, and now they produce much less. His statement that the opal is out of fashion would have been true several years ago, but is not to-day, when more of these stones are sold, and at better prices, than ever before.

The carat is given as 3.174 grains; whereas, since there are 151.5 English diamond carats in an English Troy ounce of 480 grains, an English carat would be 3.1683168 Troy grains, or, less exact, 3.168. A diamond carat is always divided into four diamond grains equalling .792074 of a Troy grain. If 31.103 grams equal an English Troy ounce, a carat would be .205304 of a gram.

An international syndicate composed of London, Paris, and Amsterdam jewellers, wishing to establish a uniform carat, in 1877 confirmed .205, however, as the true value of a carat, in which case we have 151.76 carats in an ounce Troy.

These may seem trifling differences, but yet they are enough to affect a $10,000 lot of diamonds, worth $100 a carat, to the amount of $4.83 between the 3.174 carat and the 3.168 carat, and $19.80 between the former and the syndicate carat.

It would perhaps have been better to make the reference to imperial jade, which he mentions several times, under the head of the jade-quarries of Burma, as this (Feitsui) imperial jade is jadeite, not jade, and is generally only emerald green in spots or streaks, the mass being a dead white, lending a vividness to the green which occasionally almost rivals the emerald, and has thẹ hardness of 7.

Of the articles of jade shown by the New Zealand Court at the colonial exhibition, England, Professor Simmonds says, “Evidencing the skill of the Maoris in working this hard material, the second in this respect to the diamond, although much more fragile," etc. This would lead one to infer that the material possesses great hardness, when, in fact, the hardness of jade is only 6.5, less even than that of rock crystal, and it can be worked with sand, by which laborious means, undoubtedly, all of the aboriginal ornaments of the Maori were made. So far as its fragility is concerned, it is the toughest of all known minerals, and this is the reason why it is so difficult to work. It would require less time to polish twenty surfaces of agate, which is harder than jade, than it would to polish one of jade on the same wheel. Krantz, the mineral-dealer of Bonn, having a fifty-pound piece of jade which he wished broken into small hand specimens, a friend kindly offered him the use of a large half-ton trip hammer to break it with. At the first blow the hammer was demolished, and the jade was only fractured by being heated and thrown into cold water.

We frequently hear minerals or gems loosely spoken of as second or third in hardness to the diamond. On the Mohs scale of hardness, the diamond is represented by 10, the sapphire by 9, topaz 8, and quartz 7; but, although the difference on the scale is only 1, there is room for several substances between the diamond and the sapphire; and, as we have no such known substance in nature, we place diamond on 10. In reality, so great is the difference between these two substances, that, if the hardness of the sapphire is 9, that of the diamond would be fully 100, relatively to the rest of the scale. Professor Simmonds also says that coral has the hardness

and brilliancy of agate. Quartz and agate are placed at 7 in the Mohs scale, whereas coral has only the hardness of about 3, the same as that of marble (calcite), and can be scratched by fluorite. It is impossible to see how this opaque substance can be said to "shine like a garnet, with the tint of the ruby."

A word, in closing, about the hardness of agate and rock crystal. Mineralogically these are classed together at 7; but in reality the crystalline varieties should be 7, and the crypto-crystalline varieties 7.3, since they will readily scratch quartz, and quartz will not scratch them. GEORGE F. KUNZ.

New York, Oct. 31.

Living Lights.

WE have noticed in your journal (Science, x. No. 246) a review of the book on phosphorescence called Living Lights." The writer, it seems, must have made a very hasty perusal to have failed to see that the statements therein are not conjectural, but in each case are from individuals we are accustomed to honor as credible witnesses.

The fact of this review being in the columns of a science journal is, of course, the only reason for our interest in it. The most charitable construction which we can put on this surprising exhibition of lack of knowledge is that the reviewer did not notice the array of great names which support the statements of the book, for we cannot think that any one would knowingly dispute the words of such men and naturalists.

The reviewer starts off by throwing discredit and ridicule on the entire world of luminosity, seemingly denying that attribute to all living objects. He says, "Not only do fire-flies fly, glow-worms glow, zoophytes twinkle in the sea, but sea-anemones, alcyonarians, gorgonias, star-fishes, earth-worms, crabs, shell-fish, lizards, frogs, toads, fishes, birds, monkeys, and men must be added," etc.

We confess to embarrassment in approaching the task of replying to such, for one is impressed with the notion that some occult jest is intended; but again we are reminded of the character of the journal, and a feeling of surprise follows at the incomprehensible lack of knowledge displayed regarding the subject in hand.

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Thus for twelve of the illustrations: for the remaining ones, it were absurd indeed to defend them. The former, as being matter not yet widely extant, some of it not published outside of society bulletins, may well be regarded as unfamiliar. The quotation which the reviewer takes from the book is treated so as to mislead. author evidently meant to convey that it is difficult to represent the phenomenon of luminosity in marine animals, as their integrity is injured on exposure to air, though no question is entertained of their luminosity. A kindly review of this portion would rather praise the caution exhibited by the author in stating that the pictures may possibly not exactly portray the real appearance as it exists in the sea. The statements of the reviewer are so sweeping and (possibly) damaging among those not informed, it would seem advisable to state facts, though it is a humiliating thought that the brilliant work of so many eminent men should in such quarters be unknown.

It is but justice to do this, as the author of Living Lights' is at present beyond reach, at a distance from home, and of course unable to reply seasonably.

The statement, “zoöphytes twinkling in the sea" might well have covered the ground for one group, without enumerating “seaanemones, alcyonarians, gorgonias," etc., also; but this enumeration will serve to suggest what objects concern us, as those arraigned for false attributes. We presume that few will deny the luminous gift to fire-flies, glow-worms, etc., which are mentioned in this connection. Let us, then, pass to the sea-anemone record. Colonel Pike of Brooklyn, an American naturalist not to be questioned, has given at length his testimony, and we know that the author himself has an experience as to their luminosity, which,

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