Madagascar and New Zealand are of older separation, the latter approaching the restinseln.

The term 'oceanic' is discarded for the second group, because islands may be formed de novo close to continental shores; but the term proposed ('original') is not altogether satisfactory, as it does not express precisely what is meant. The first subdivision (volcanic islands) contains the most important examples, which have sometimes, from their considerable age and altitude, acquired peculiar and local organic forms. The second subdivision (heaped-up islands) includes those of coral and of sand, on which the dry surface is due to wave and wind action. These are all low and monotonous. The third subdivision includes portions of the sea-bottom laid bare by non-volcanic action, either by local elevation "or by withdrawal of the sea formerly held at a higher level by the local attraction of mountains or ice masses that have now disappeared." A single example of recent formation is given, the so-called 'Gulf-stream island,' northwest of Novaya Zemlya, where the Dutch navigators of 1594 found a sand-bank in seventeen fathoms of water. Peschel's error of placing the Japanese and Philippine islands among the volcanic is corrected: they are included among the continental, as both contain a series of old non-volcanic rocks.

W. M. DAVIS.

LETTERS TO THE EDITOR.

A new form of battery-cell.

IN the ordinary voltaic element, two solid plates are acted upon unequally by one or more liquids. About three years ago, it occurred to me to construct a battery-cell with three non-miscible liquid strata, and no solid plates; which I did, as follows: in a small beaker-glass I placed successively layers of mercury, dilute sulphuric acid, and a solution of iodine in ether. Upon connecting the uppermost and lowest layers with insulated wires, and introducing a coarse galvanometer into the circuit, I obtained evidence of a fairly strong current of electricity. Having neither time nor opportunity to pursue the matter further, I put it on record now in order that any student who happens to be interested in the subject may carry out the investigation. Theoretically, a three-liquid cell is interesting, because its internal resistance ought to diminish with rise of temperature. In this respect it might be very different from the usual voltaic elements. Possibly a combination of solid plates with the upper and lower liquids might give a cell having an internal resistance constant for varying temperatures. F. W. CLARKE,

Correcting compass deviation.

Some years ago, frequently recurrent shipwrecks from magnetic disturbance in the Gulf of St. Lawrence directed my attention to the subject of improving the mariner's compass, or supplementing it in some way which would make its indications trustworthy. The causes of the shipwrecks which I have mentioned seemed to be deposits of iron ore near the shore, so extensive in their area as to render the compass-reading false and misleading. The problem of improving the compass is an important one; for, apart from such risks as those which beset navigation in the Gulf of St. Lawrence, the deviation on board ship due to the presence of iron in the structure or cargo of the vessel is an element of some uncertainty, and danger even, when all the devices known to the mariner's art are used to correct the readings.

Poised concentrically with the strip at such a distance as to avoid mutual influence, I placed a light magnetic needle of a length equal to that of the strip. When strip and needle were near enough to a piece of iron to be attracted by it, one of the two acute angles formed by them indicated the position of the disturbing iron; and this inclination at an acute angle promised to be of value in solving the problem of correcting compass-readings. But magnetic influence on the large scale which prevails on shipboard proceeds from distant centres along large curves, in which terrestrial and local forces merge, which are not attractive, but simply directive; so that when I tried my device on a steamer under very favorable experimental circumstances, as the magnets, large and small, were directed into curves so great as to be practically straight lines, the needle and strip were always at right angles with each other. Were it feasible to use a very long magnetic strip at sea, my device might be available; but, so long as ships roll and pitch on the ocean's unruly surface, the dimensions of the ordinary compass must remain as they are. Since abandoning the fragile little model which I launched with some expectations long ago, I have frequently reverted to the problem it was intended to solve; and it has occurred to me, that were an electro-magnet poised so as to be in constant and free communication with a battery, and were it possible to make it, when desired, so intense in its power that its induction affecting the iron of ship or cargo should increase the deviation which, when less intensely excited, would affect it, then the direction of the deviation would be, of course, known by the direction of the increase of that deviation, and the problem of correcting the compass-reading would be advanced a step. The intensity of the electro-magnet would yield such results as a long (impracticably long) magnetic strip. The electromagnet would require to be so constructed as to be capable of developing the utmost intensity possible; and the current sent through it should be controllable at will, so that the indications at moderate and highest intensity might be compared. I have neither the skill nor opportunity to carry out the suggestion here given, and publish it in the hope that some competent man of science may be able to embody it in a practical and useful form. GEORGE ILES.

Montreal, May 25, 1883.

MAINE'S EARLY LAW AND CUSTOM. Dissertations on early law and custom. By Sir HENRY SUMNER MAINE, K.C.S.I., LL.D., F.R.S. New York, Henry Holt & Co., 1882. 402 p. 8°.

WHEN a new book by Sir Henry Maine is announced, we expect to have something to read worth reading. Nor have we ever been disappointed. The author of Ancient law has always something interesting, suggestive,

instructive, to say. He gathers up the gist of contemporary thought, and presents it in a simple, lucid way, and always contributes something new from his own mind. The specialist finds, sometimes, a lack of definition, of exhaustive analysis, and here and there more or less serious errors. In spite of this, however, he must admit that we have no more interesting, no more instructive writings than these; that the reasoning is generally clear and sound; that the errors are, as a rule, incidental.

The present volume is divided into eleven chapters, to one or two of which notes of some length are appended. The first four chapters are devoted to early law in its relations with religion. Ancestor worship is discussed at length. We are told how the worship of father, grandfather, great-grandfather, and other ancestors, remembered or capable of being remembered, has among the Hindus a most elaborate liturgy and ritual. Our author thinks that wherever ancestor worship arose paternity must have been recognized. The father's power must, he tells us, have been antecedent to the practice of worshipping him. This seems a sound conclusion. When, however, we are told that ancestor worship preceded the existence of laws of inheritance, we demur. It is quite possible that ancestor worship originated as an expedient for preserving the knowledge of genealogical relationships, inheritances being determined according to these relationships. It has been very well said by Mr. Skene, that the genealogical table was to early society what the title-deed has been to society of medieval and modern times.

In chapters v. and vi. our author takes up the subject of royal succession and kingship in its connection with early civil justice. These chapters are very instructive. But on p. 131 we find the following statement: The past of the west lives in the present of the east.' This seems to us open to some criticism. Does our author mean to say that the gaps in the early history of the west may be filled up by importations of eastern custom? If so, we must make a protest. This is a very dangerous method, and not a scientific one. Without doubt, existing institutions in the east suggest to the student of institutions in the west hypotheses which he may profitably use as hypotheses; but they must not be used in any other way. The late Mr. Morgan was led into many errors by filling gaps in the history of one nation by extracts from the history of others. We remember our astonishment when we read his account of the Roman gens, in which he fills up the blank spaces of Gaius with importations

from America. We are not a little pleased to see that Sir Henry Maine does not follow him in this. He says (p. 283), "The Agnati were a group of actual or adoptive descendants, through males, from a known and remembered ancestor the Gentiles were a similar group of descendants from an ancestor long since forgotten." His note upon the gens is extremely interesting and valuable.

Chapter vii., upon the theories of primitive society, will, perhaps, be read with more interest than any other in the book. It is an argument to support the theory of patriarchal families against the theory of promiscuous hordes, against the theory of McLellan and Morgan. Have we any right to assume that the intercourse of men and women was in early times promiscuous? Sir Henry Maine thinks not. The first fact in sociological development is, according to his view, the family. Promiscuous intercourse, in so far as it has existed, he regards as due to the cultivation of unnatural, abnormal instincts, or else to a deficiency of women at certain times and in certain places. The origin of the family he traces to sexual jealousy, which he describes, rightly enough, as one of the strongest of animal instincts. In short, he takes very much the position which Mr. Darwin takes in his account of the descent of man. Sir Henry Maine defines the patriarchal family as the result of sexual jealousy indulged through power. This is a very good phrase. The whole argument, indeed, is vigorous and strong.

The house community (chapter viii.) is the next stage in sociological development. Then comes the village community, and lastly the manor. Nor is it possible for me to doubt that the typical manor arose out of the village community." Our author makes this statement on p. 331. The inquiry suggests itself: Why should not the patriarchal family take the form of the manor, and why should not the village community grow up within the manor? Had we space, we should like to discuss this matter at length. Sir Henry Maine does not sufficiently consider the fact that the patriarchal family includes, usually, an assemblage of dependents and slaves. Why not derive the manor, with its tenures and its customs, out of this group, and the village community out of the manor?

The last three chapters of the book (ix., X., xi.) are devoted to the decay of feudal property in France and England, to classifications of property, and to classifications of legal rules. We regret that we have not space to speak more particularly of their contents. On the

whole, the book is singularly interesting, and well worth reading. We may be able hereafter to notice more in detail, and discuss more fully, some of the themes which Sir Henry Maine has made so attractive.

REPORT OF THE UNITED STATES ENTOMOLOGIST.

Report of the entomologist (of the department of agriculture) for the fiscal year ending June 30, 1882. By C. V. Riley. Washington, Government printing-office, 1882. 167 p., 20 pl. 8°.

THE report before us, which is extracted from the annual report of the department of agriculture, is not only the most voluminous contribution to economic entomology of the year just closed, but it presents the results of the most extensive investigations in this field during that period. The author, an entomologist of unusual ability and experience, was aided by a corps of very efficient assistants, and had at his disposal a large appropriation. This combination could not fail to produce impor

tant results.

It is to be regretted that the report reflects the character of too many other public documents, in that much is printed which has not the slightest permanent value; letters, for instance, from correspondents, often in full, which could have been advantageously reduced to half their extent; or accounts like that of the invasion of the army-worm in New Jersey, which is pleasant reading enough, and well suited to a popular journal, but out of place here in the form in which it is cast. Very different from these are the portions written by the entomologist and the members of his staff: these are direct, and to the point."

As the volume containing this report may be had for the asking, it will be in the possession of all who are especially interested in economic entomology. On this account, it is not worth while to refer, in this place, to each of the many topics discussed. A few of them are of general interest.

The circular which accompanied the seeds of Pyrethrum, that were distributed by the commissioner of agriculture, is reprinted, and is illustrated by two excellent colored plates representing the flowers and leaves of P. roseum and P. cinerariaefolium. The circular gives a résumé of what is known respecting the history of Pyrethrum, the method of preparing the powder, and the modes of using it. Dr. Riley adds reports from persons to whom seeds were distributed. Only a few persons succeeded in raising good plants. These were

chiefly in the north. The failures were probably largely due to drought and bad seed. report of experiments with the powder, by Miss Murtfeldt, is also given.

Acting under the direction of Dr. Riley, Mr. Hubbard experimented upon scale-insects with various insecticides, and especially with emulsions of kerosene and milk. These emulsions were the most efficient of the substances used.

Several insects infesting the rice-plant are described. The rice-grub is the larva of a beetle (Chalepus trachypygus). This insect feeds upon the roots of rice, and has done considerable damage to rice-plantations. Howard states that the larvae and adults are both destroyed by the harvest-water;' and consequently the breeding-places must be those fields which are not flooded, and the patches of volunteer rice. Therefore the insect can be easily kept in check, except where upland rice is grown. The rice-stalk borer (Chilo oryzaeellus) is a new lepidopterous insect described by Riley. The habits of the larva, which are indicated by the popular name, are reported by Howard.

Economic entomologists will note with especial interest the discovery of the larva of the 'corn bill-bug' (Sphenophorus robustus). This larva infests the stalks of corn at or near the surface of the ground. If, as is now supposed, the adult beetle hibernates in the stalk, ploughing up the stubble, and burning it, will be a simple remedy.

The smaller corn-stalk borer' (Pempelia lignosella) is a new corn-pest which is very destructive in the Carolinas and Georgia.

In an article on the cotton-worm, a machine for spraying the cotton-plant from below is described, and illustrated by a full-page figure.

Embodied in this report is a part of a report on miscellaneous insects, made by Prof. J. H. Comstock to the commissioner of agriculture; the most interesting portion relates to lac insects, of which two species are described from Mexico and the adjoining portion of the United States.

MACGREGOR'S BALUTCHISTAN. Wanderings in Balochistan. By Sir C. M. MACGREGOR. London, Allen & Co., 1882. 315 p., illustr. 8°.

THIS is a rather loosely written narrative -with a tendency to slang expressions, such as green funk,'' make tracks' — of a reconnaissance expedition undertaken in 1876-77, in company with Capt. R. B. Lockwood, who,

unhappily, died shortly after the end of the journey from the effects of exposure. There is a provoking lack of appreciation of geographical form, and a want of understanding of geological structure, that deprives the observations of much value; and the pen-drawings that illustrate the book in good number are extremely rough. Perseverance and energy are, however, apparent enough in the success of the expedition; and the itinerary notes as to roads, supplies, and water, have a great value for those who may have to repeat the author's journey in this desert country. The party entered from the southern coast at Gwadar; and, after traversing for some two hundred miles a barren region of flat valleys or plains abruptly broken by mountain ranges, they reached the desert interior basin, into whose depressions the Mashkel flows from the south; the Halmand and others, from the north-east and north; and several smaller temporary streams, from the surrounding or dividing ranges, forming salt plains or marshes (hamun) at the lowest points. This district is absolutely barren, and very flat, broken only by sand-ridges, or occasional rocky peaks that rise like islands over the level plain. The largest central depression, known as the God-i-zirreh, is a dry salt waste about seventy miles long east and west, and twenty miles wide, surrounded by a barren sandy desert; and the passage across the southern margin of this desolate tract, hitherto unexplored, to a point named Shah Godar, exposed the explorers to great hardships. Water was found there only by digging in the sand of a dry streamchannel (175-185). This was their farthest station; and from it they returned eastward to Jacobabad, in Sind. The people were found avaricious and untrustworthy: their towns

The

were of the most forlorn description. difficulty of learning local names was not small. The instructions given by a local official to a guide who was to accompany Macgregor were overheard by him: This sahib will ask you the name of every hill, every river, and every hut you see.'-'What for?'-' Heaven only knows! These sahibs always do that: they ask the name of every thing, and then write it down.' But how am I to name all the hills?'

-Call them any thing you like, and he will write it.' It seems, that while the people have names for the ravines that they follow, and for the stopping-places on them, they generally have no names for hills and ranges; nor have they any idea of the connection of mountains with each other, or of any system of drainage. Sand-hills are very numerous on the deserts; and, on the plain north of the Mashkel hamun, a peculiar form was noticed, provoking one of the few pieces of careful description in the book (p. 157). The examples were very numerous, and all closely alike; their form was crescentic, and the largest were sixty feet high at the middle of the curve, descending to the general level at the horns; the outer slope is 30°, and the inner 45° with a still steeper inclination at the outer side of the top of the ridge; they stand on a perfectly level plain, with the curve to the north or windward, and horns to the south. One would afford cover enough for a regiment or two.' The author imagines that some obstruction like a bush formed the nucleus about which the sand originally gathered. A sketch-map accompanies the volume; but there is often an unfortunate disagreement in spelling between it and the text. Table of contents and index are lacking.

MATHEMATICS.

Strain of an isotropic solid. Mr. Stearn has given a very brief method for obtaining the expression for the internal energy per unit volume of a strained isotropic solid. — (Quart. journ. math., Feb.) T. C. 1967 Elliptic functions.-Mr. Glaisher has given a series of integrals of functions depending upon elliptic functions. The paper is of such a character that it is impossible, in this place, to do more than refer to it. It may, however, be remarked that the set of integrals obtained constitutes a valuable addition to the known elliptic function formulae. A continuation of the investigations may be inferred from the manner in which the author has introduced the present article. (Quart. journ. math., Feb.) T. c. [968 Spherical triangle. - Professor W. W. Johnson

remarks, that in the proof of the addition theorem in elliptic functions by means of a spherical triangle whose sides are o, y, and μ, where = am u, = amv, μam (u + v), and k is the ratio of the sines of the angles to the sines of the opposite sides, it is usual to state that the angle opposite to the side μ is obtuse, so that its cosine is Au, if the other angles are acute, so that their cosines are Ap and Ay. This may be shown to be a consequence of the assumption that k is less than unity. The present note aims to show that the restriction, k < 1, may be removed, in accordance with which Au is always positive; proving directly, that, in all cases, the cosine of the angle in question is -Au. It is further shown, in order to complete the proof, that the triangle from which the formulae are derived is possible for all real values of u and v, as well as k.- (Quart. journ. math., Feb.) [969

T. C.

PHYSICS.

Liquefaction of oxygen and nitrogen, and congelation of carbonic disulphide and alcohol. On boiling ethylen in vacuo, Wroblewski and Olszewski obtained a minimum temperature of -136° C. With the temperatures thus obtained, which were measured with a hydrogen thermometer, experiments were performed on liquefaction and congelation. Under the pressures 26.5, 24.8, and 22.5 atmospheres, oxygen began to liquefy at the temperatures -131.6°, -133.4°, and -135.8°. It formed a colorless and transparent liquid with a well-defined meniscus. Carbonic disulphide congealed at -116°, and melted at -110°; alcohol became a viscous oil at -129°, and solidified at -130.5°; nitrogen formed a colorless liquid with a visible meniscus. (Comptes rendus, xcvi. 1140.) C. F. M. [970

Electricity.

Alleged luminosity of the magnetic field.Professor W. F. Barrett says, "It is well known that the late Baron von Reichenbach claimed to have discovered a peculiar luminous emanation arising from the poles of a magnet, resembling a faint electric discharge in rarefied air."

Prof. Barrett and several other gentlemen, members of a committee appointed by the Society for psychical research, have been making experiments with a view to proving or disproving the existence of the alleged phenomenon. No member of the committee appears to have been able to see the emanation; but the committee did discover, in some way not detailed, a certain gentleman, Mr. G. A. Smith, and a boy, Fred. Wells, an assistant in a baker's shop,' who each appeared able, in a room perfectly dark to other people, to see a faint glow, like a waving cone of light, at either pole of a strong electro-magnet, and to tell, by the appearance or disappearance of this glow, when the current was turned on or off by means of a commutator in charge of several gentlemen in an adjoining

room.

Theoretical mechanics. — Mr. George F. Swain presents an article upon the application of the principle of virtual velocities to the determination of the deflection and stresses of frames. An exact method of finding the elastic deflection in any direction of any point of a frame of any kind, due to Lamé, is first explained. The determination of deflection is in itself a problem of small importance. It finds its application, however, in the calculation of the so-called 'statically undetermined' structures, such as the continuous girder, and the arch with fewer than three hinges, where the forces acting depend upon the condition that the deflection of some point in the frame in some particular direction must be a given quantity. These structures are taken up in succession, and the general equations to be used in their calculation are given. Trusses with superfluous bars are next discussed; and a historical account of the literature of the subject closes the article.-(Journ. Frankl. inst., Feb., March, April.) G. L. V. [972

Naval iron vessels. The advisory board of the navy department reports in favor of fitting up the League Island navy-yard to build the iron and steel ships to be constructed. (Bull. iron steel assoc.. April, 1883.) R. H. T. 1973

Forced draught in steamers. - Experiments on the Satellite and Conqueror, reported by R. J. Butler to the Royal institute of naval architects, indicate that forced draught is not advisable on long runs, but that it is useful on runs of less than six hours. For such cases a fan draught is recommended. (Engineering, March.) R. H. T. [974

Hydraulic machine-tools.- Mr. R. H. Tweddell describes to the British institute of civil engineers forms of machine-tools driven by hydraulic pressure. Riveting has long been practised with hydraulic riveters; hydraulic stamps and forging-presses are now made to do good work; machine-tools have been made by Armstrong; and an hydraulic system of power-transmission has been adopted at Penhouet, France. Portable hydraulic machine-tools are found to save greatly in floor-space, and to save power as well. · (Engineering, March 23.) R. H. T. [975

CHEMISTRY.

(General, physical, and inorganic.)

Borotungstic acids.-D. Klein prepared disodic borotungstate (14 WO,. B2O3. 2 Na2O. 4H2O+ 25 H2O) by adding the required amount of boracic acid to neutral sodic tungstate. Although other salts were prepared from the sodium salt, several attempts to separate the acid in a state of purity were unsuccessful. The mother liquors of the sodic borotungstate contained a sodium salt of tungstoboric acid, which was precipitated as the barium salt by adding baric chloride. This acid, which is comparatively stable, was prepared by treating the barium salt (9 WO,. B2O ̧ . 2 BaO+18 H2O) with dilute sulphuric acid. Tungstoboric acid proves to be a convenient reagent for characterizing the alkaloids and peptones. With even a minute quantity of the salts of quinine, cinchonine, strychnine, morphine, and codeine, it gives a white precipitate. With peptones it behaves like phosphotungstic acid. The author finds that cadmic tungstoborate is well adapted for use in the mechanical separation of the mineralogical elements of rocks in petrography. In the solid form, its specific gravity is 3.28, and a liquid may be obtained from it of any density between 1 and 3.8. At 75°-80° it melts in its water of crystallization, giving a sirupy liquid of sufficient density (3.7) to float garnet or spinel. — (Ann. chim. phys., xxviii. 350.) C. F. M. [976

Action of chlorine on certain metals. When thoroughly dried chlorine was allowed to remain in contact with Dutch metal, A. Cowper found, that, apparently, no chemical action had taken place at the end of three months. On introducing even a trace of moisture, the chlorine was rapidly absorbed. Zinc and magnesium were not attacked by the gas after it had stood several days in contact with fused calcic chloride. Silver and bismuth were acted on slowly; while tin, antimony, arsenic, and mercury were atIn tacked with the same energy as in the moist gas. the dried gas, sodium remained untarnished. Potassium, at first bright, became slowly covered with a purple film, probably of the subchloride. - (Journ. chem. soc., cexliv. 153.) C. F. M. [977 Drying gunpowder magazines. It having been officially recommended that chloride of lime should be used for removing the moisture from magazines, Prof. Munroe held that this was due to a con