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references make it difficult to detach any one from the "meteoric stones," and showed the immense number rest, or to gather the substance of the author's specula- of facts that he had found out about them. In this tions on any one part of his subject. In the preface he one word fact--fuct-lies a great world of difference tells us that he had been urged to publish not a reprint, between Chladni's meteoric stones and Oudemans's sea. but a systematic treatise. It is, we think, greatly to be serpents. The meteoric stones could be seen and regretted that he has not found it possible to take this handled, the sea-serpents “are very shy, and it is not advice. The labour of compression and of proper advisable to approach them with a steamboat." "Instan. co-ordination would no doubt have been great, but taneous photographs of the animal will alone convince it would have been amply repaid by the increased zoologists, while all their reports and pencil drawings currency given to the author's views. As it is, we fear will be received with a shrug of the shoulders"; this that the fate of these weighty volumes will be that students + latter sentence, which precedes the preface, makes one of the stamp which Mr. Heaviside would most wish to shudder at the amount of “reports and pencil drawings" attract will turn over his pages, picking up a suggestion contained in the six hundred following pages. here and there, will then work out things in their own And yet, perhaps, this work is not altogether without way, and finally return to the present treatise to ascertain its value. From the middle of the sixteenth century-wben how far their results have been anticipated. And this is Olaus Magnus wrote about “ a very large serpent of a really matter for regret, for almost every page bears the length of upwards of 200 feet and twenty feet in diameter, impress of a vigorous and original mind, and we cannot which lived in rocks and holes near the shore of Bergin doubt that the author's speculations would have exercised i Muntil this very present hour all sorts and manners a considerable influence on the progress of electromag- of gigantic forms have been reported about by netic theory, if it had not been for the disadvantageous sailors and others, and even pencil drawings of them form under which they are presented.

H. L. have been made, and the collecting together and printing

of such a series of records forms as strange a chapter of the science known by the people as has ever made its

appearance. THE GREAT SEA-SERPENT.

There is but little necessity of insisting on the need The Great Sea-Serpent. An Historical and Critical of experience in seeing ere one can describe what is

Treatise. With Reports of 187 Appearances (including seen, nor on the need of a power of describing those of the Appendix), the Suppositions and Sugges what one correctly sees so that the description may tions of Scientific and Non-scientific Persons, and the be applicable, nor need one wonder that such powers Author's Conclusions. With 82 illustrations. By A. of seeing and describing were not to be found united C. Oudemans, Jzn. Published by the Author, October, in the many seagoing worthies whose extraordinary 1892. (London : Luzac and Co.)

| narratives crowd the pages of this volume. But what IN a large, well-printed volume, Dr. A. C. Oudemans, are we to say about the capacity for belief to

1 Jzn., publishes what he is pleased to call "an be found in the compiler of this work, who conhistorical and critical treatise" about the “Great Sea- cludes his task by naming a form he has never seen, Serpent,” with the reports of 187 appearances, the suppo- | Megophias megophias (Raf.) Oud., and further thinks sitions and suggestions of scientific and non-scientific that a Phylogenetic table, which he gives, “will in a persons, and the author's conclusions.

practical manner show the rank which, in my opinion, It is impossible, however, to treat this laborious work sea-serpents occupy in the system of nature"? as a scientific treatise, nor will the author, we trust, be This volume contains an account of the literature* on vexed with us when we add that it is the very last form the subject of sea-serpents; a detailed record of the of a work that we would have expected from the pen of various accounts and reports concerning observations of the learned Director of the Zoological Gardens at the sea-serpents chronologically arranged and thoroughly Hague. for when one gets by practise to know the utter discussed ; and criticisms on the papers written on the worthlessness of the descriptions given by even well-edu- same subject; next the various explanations hitherto cated persons of often the most easily diagnosed forms of given, and lastly the author's own conclusions-these he life--and surely experience of this nature must often have divides into “fables, fictions, exaggerations and errors." come across Dr. Oudemans's path-one cannot fail to and what he is pleased to call “facts." Among the ficregard as positively hopeless the reconciling of a mass of tions he regards the belief that the sea-serpent “casts such crude observations as fill the pages of this book. its skin, as common snakes do, and that it is born on The very trouble and no doubt anxiety caused by reading land"; among the exaggerations that it has “a tail fully over such a pitiful series of records has to some extent a hundred and fifty feet in length”! among the errors affected the author, for he quotes as the motto for his “that there are two species of sea-serpents, or that there volume the extremely sensible words of a very able are several species of them all belonging to the same biologist, whose chief fault it was not to leave a greater genus"; or that "it ever takes (mistakes) a boat for one record of his wisdom for posterity, to the effect“ That it of the other sex.” is always unsafe to deny positively any phenomena that As to the facts, which may be—it is well to note may be wholly or in part inexplicable,” meaning thereby | "inferred from what is reported," we find enumerated to deny a phenomenon because it cannot be explained, among them the external characters of the sea-serpent, and then in the immediately following preface he its dimensions, form, and skin. Of its internal charac compares himself to Chladni, who took the trouble ters “it is not astonishing that we don't know much." to collect all the accounts concerning observations of yet it is clear “ that if the animal opens its mouth there

is an opportunity to learn something about its teeth, country, the author is nevertheless able to introduce a tongue, &c.," and so we get a series of “inferred” facts | mass of detail relating to practical sanitation which we about them. We have further details of its colours, believe would be looked for in vain even in our standard sexual differences, a very full account of its “physiologi- | text-books on hygiene. We may instance as examples cal characters," some of its "psychical characters," con- of this the paragraphs on the scavenging of London, and cluding with its enemies, its repose, its sleep, and its the disposal of rubbish and street refuse ; the description death.

of the preventive measures adopted in this country for Enough has been written to prove that this volume is the limitation of the spread of infectious disease, together not without a certain amount of interest. We have found with an account of the ambulance service and hospital it a rather troublesome task to read it through, but to ships; the explanation of the methods adopted for the open its pages at random one is sure to be arrested by ventilation of some of our important public buildings; some startling phase of belief or by some marvellous the excellent résumé of school hygiene, for which we have narration, and the first half of the book very certainly no doubt the author is deeply indebted to Dr. Newsholme ; deserves to be described as a conscientious compilation and the summary on industrial hygiene, although the It is written in most excellent English.

author is rather inclined to repeat many of his remarks | under this head when describing “the sanitary provisions

as to industries.” Dr. Palmberg's admiration of English PUBLIC HEALTH.

sanitation is pronounced, and in commenting on our A Treatise on Public Health and its Applications in appreciation of the beneficent results of good ventilation,

Different European Countries. By Albert Palmberg, we find him giving vent to the quaint statement that M.D., Medical Officer of Health for the County of "even in cold weather the windows of high houses are Helsingfors in Finland. Translated from the French opened, children and adults without fear of chill breathedition, and the section on England edited by Arthur ! ing the pure air"! Newsholme, M.D. (Lond.), D.P.H., Medical Officer of France, the author informs us, has no general sanitary Health for Brighton. (London : Swan Sonnenschein law, most of the sanitary regulations in force consisting and Co., 1893.)

of ministerial decrees, orders of prefects and councils of ALTHOUGH scarcely more than a year has elapsed health. Corresponding to this laxity of sanitary control, A since the issue of the Swedish edition of this work, the great sanitary improvements which have been from translations of it have already appeared in French, time to time introduced have not been followed in Paris English, and Spanish. A book which within so short an by a continuous fall in mortality, as in the case of the interval has attained to such a pitch of popularity may other European capitals. As the author very rightly be admitted to have practically established its claim to remarks, the time is past when it can be supposed that rank amongst the important contributions towards the good sense and administrative capacity merely suffice for literature of the subject with which it is concerned. Ex- the regulation of the Public Health. The drainage of tensive indeed as is the ground travelled over by the Paris is exhaustively treated, the sewerage of the town author, yet so ably has the material been handled, that being dealt with in detail, the writer in the course of his we feel it to be a matter for regret that the writer was description pointing out that the system in use is objecunable to deal with the hygienic administration of all, tionable, inasmuch as it allows deposits of sand to occur, instead of a portion only, of the important European and necessitates the maintenance of an army of 850 men countries. The sanitary administrations of England, to keep the sewers clear, the workers themselves at the Scotland, France, Germany, Austria, Sweden, and Fin- same time having a relative mortality from typhoid fever land are detailed ; but the description of the Public Health | twice as great as that for all Paris. Moreover, owing to service of Russia, Denmark, Norway, Holland, and Italy the friction of the enormous deposits of sand in the sewers is omitted. Not having visited these countries, and the wear and tear on the latter are great, and compel studied the subject by a personal inquiry on the spot, Dr. | frequent repairs. Palmberg very wisely preferred not to deal with them at The sanitation of Germany and Austria is dealt with in all, rather than run the risk of making inexact statements the same thorough spirit as pervades the rest of the book concerning them

and calls for no special remark. In treating of the various countries, the plan which the In the description of the general regulations in force in writer has followed has been first to give a brief summary Sweden relating to hygiene in towns, we think, however, of the sanitary laws in force, and then to describe in that these laws might with advantage have been more detailthe methods adopted in the capital towns for carrying systematised, much after the plan that the writer has out these regulations. Of all countries England claims the adopted in dealing with Finland. largest share of attention, Dr. Palmberg assigning to her The translation is remarkably well done, and with one the chief place amongst the nations for the excellence of exception is quite free from the sort of mistake usually her Public Health administration, and the care with met with in English editions of foreign works. The which all matters connected with hygiene are attended instance we refer to occurs on page 380, where the author, to. The chapter on England contains a good résumé of in describing the forms of stove ordinarily employed in our principal sanitary laws, together with a summary of Germany, makes use of the following words :--“Although the model bye-laws of the Local Government Board. | the construction differs from that of the English ventilatThe description of sanitary apparatus is excellent, the ing stoves made by Douglas Galton and Boyle and Son." text being plentifully supplied with illustrations. Not- | Dr. Palmberg's book is undoubtedly a valuable one. withstanding the limited space which is allotted to each and should prove of the utmost utility to all interested in

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sanitary science. By placing in our hands a description and composite numbers, squares, cubes, square roots, of the Public Health systems in vogue amongst con

&c., Bessel's coefficients for interpolation to the fifth tinental nations, it allows us the opportunity of comparing

differences, binomial coefficients for interpolation, also

for fifth differences, and lastly a useful table of the errors them with our own, and correcting our shortcomings by

of observations, from which we can at a glance determine their experiences. Notably should this be the case in

the ordinates of the probability curve, values of probaour methods of food inspection.

H. BROCK bility integrals, &c. An explanation, preceding the tables

themselves, shows how they may be advintageously used, and the author offers the reward of "a dollar" for

the first notice of a mistake "to promote the detection of OUR BOOK SHELF.

errors." The English Flower Garden: Style, Position, and Catalogue of the British Echinoderms in the British

Arrangement ; followed by a Description of all the best | Museum (Natural History). By F. Jeffrey Bell, M.A.
Plants for it, their Culture and Arrangement. By W. (London: Printed by Order of the Trustees.)
Robinson. Third Edition. (London: John Murray,

DURING recent years many additions have been made 1893.)

to the collection of echinoderms in the British Museum; This quite recently published new edition of this most and, as Dr. Günther explains in his preface to the present charming and useful book has been so completely altered volume, much time and labour have been given to the as to be at first sight scarcely recognisable, and we are study and arrangement of these additions. It seemed glad to record that all these alterations have been im- expedient, he says, to prepare, together with the nominal provements, the result of a determination on the author's list of the specimens, a complete account of the species part never to give up the effort of making it better. In | hitherto found in British seas. All students of the subject the present edition the old plates, many of which con- will congratulate themselves on the fact that this decision tained but feeble portraits of plant life, have been broken was arrived at, for the result is that they are now provided up, and in their places we find delightful pictures of some with a handbook which will enable them to identify, of our best loved flowering shrubs and plants, at one time without much difficulty, any specimens that may come represented as growing over walls or cottage porch, or in their way. Mr. Bell, in beginning the preparation of again by the lake or riverside. All of these are perhaps so full a catalogue, had before him a task of no small not equal in execution, but it has seldom happened to us difficulty, and in the manner in which he has discharged to see so large a number of illustrations with so few that it he has displayed great patience, insight, and know. are below a high standard. Such delightful woodcuts as ledge. A number of well-printed plates add largely to those of the double flowering hollyhock, the Alpine pink, or of Rodgersia podophylla brighten up the pages and add much of interest to this book. So familiar is this volume

--- - --------------to most lovers of plants, of which the fact of three editions

LETTERS TO THE EDITOR. within ten years is a satisfactory proof, that it seems almost needless to explain that the first portion of it is [The Editor does not hold himself responsible for opinions ere devoted to a series of chapters on such subjects as design pressed by his correspondents. Neither can he undertake and position of a garden, on the wild garden, the Alpine to return, or to correspond with the writers of, rejected garden, on spring, summer, and autumn flowers, and we

manuscripts intended for this or any other part of NATURE. note even on “ Pergolas," the illustration of this latter

No notice is taken of anonymous communications. ] being from Venice. Alas! in these northern countries

The Hatching of a Peripatus Egg. our sunshine scarcely ever needs a shade. The whole of

IN NATURE, vol. xliv. p. 468, I briefly described some the first portion of the book is rewritten, and many new

eggs of the larger Victorian Peripalus, which were laid by illustrations are given, such as the “ primrose garden in

specimens kept alive by me in the winter (Australian) of 1891. a small clearing of a birch wood” in Surrey, the group of At that time, following previous authority, I identified the “Solomon's seal at the foot of a wall," and others too species which laid the eggs as P. leuckartii. It appears now, numerous to mention.

however, that the real P. leuckartii – at any rate, in New South The second and much larger portion is devoted to a Wales—is undoubtedly viviparous, and our oviparous Victorian list, arranged in alphabetical order, of all those plants species is, therelore, probably distinct. (It may be remembered that have been grown successfully in the gardens of Great that in NATURE, vol. xxxix. p. 366, I suggested this probBritain and Ireland, and of some few that may be ex

able distinction on account of the remarkable pattern of the pected to grow there. Like the rest of the volume, this

skin usually exhibited by the fifteen-iegged Victorian form.) part too has been very thoroughly revised and brought

Further particulars on this subject are given in my "Further

Notes on the oviparity of the larger Victorian Peripatos, up to date. To every one in the possession of a garden,

generally known as P. leuckartii,"] and in the literature cited or having the care of one, we would say study this

therein. In that paper I described two embryos, removed from “English Flower Garden,” for you cannot do so without eggs which had been laid for about three and eight months re profit.

spectively. In the latter case I showed that the embryo was

possessed of the fall number of appendages, and was in all reLogarithmic Tables. By Prof. George Willia m Jones.

spects a perfect young Peri palus, differing externally from the (London: Macmillan and Co., 1893.)

adult only in the smaller size and less deeply pigmented skin This book of tables, which we notice has reached its On the strength of ihese observations I claimed to have definitely fourth edition, will be found to serve the purpose for

proved that the larger Victorian Peripatus at any rate some many computations which require an accuracy extending

times lays eggs, and that these eggs are capable of undergoing

development outside the body until perfect young animals are only to four or five places of decimals. The tables

produced. I am now able to add some further information. throughout seem to be well arranged, and the figures

For some time only one egg (belonging to the original lot, for neatly printed, thus fulfilling two important requirements

none have since been obtained) remained in the hatching box from the computer's standpoint. In addition to five

The shell of this egg had changed to a dark brownish colour, place logarithms there is a table to four-places, together and latterly an embryo had been visible through the shell, coiled with four-place trigonometric functions, a table of useful up inside. The egg was lying on a small piece of rotten wood, constants, and an addition-subtraction table. Among which rested on the glass floor of the batching bos. Os others we may mention a five.place table of natural sines,

L 1" Proceedings of the Royal Society of Victoria," vol. v. p. 27: also

Annals and Magazine of Natural History, 1892.

January 3, 1893, not having opened the box for some days, Il Hence, constants for thirty-first century are the same for the made an examination. The egg was in its former position, so present century. far as I could tell, but the shell was split on one side and the young Peripatus had escaped. This young Peripatus was

New Year's Day, 3001, found lying dead on the glass floor of the hatching box, 25 mm.

A B C D Sum. Remr. distant from the shell. It must have crawled off the rotten

i 3 1 0 5 5 Thursday. wood and along the glass to the position in which it was found. For centuries anterior to the eighteenth we must first of all It was only about 5 mm. in length, so that, even assuming that it find by special method what the dionthly constants would have moved in a perfectly straight line, it must have crawled for a dis- been throughout the eighteenth century without the change of tance five times its own length. To the naked eye the young style, and then subtract 6 for each century short of the animal appeared of a pale greenish colour. It could not have been eighteenth. dead for very many days, but decomposition had already set in, It may easily be seen that the constants throughout the and the animal was stuck to the glass on which it lay. It was

eighteenth century would have been without change of style. impossible to remove it without considerable injury, but I

Jan. Feb. Mar. Ap. May June July Aug. Sept. Oct. Nov. Dec. ultimately succeeded in mounting it in Canada balsam, and it

2 5 5 1 3 6 1 4 0 2 5 is impossible, even in its present condition, to doubt that it

0 really is a young Peripatus, for the characteristic jaws and claws

For the eleventh century subtract 7 x 6 or 42, i.e. since are well shown. I also mounted the ruptured egg-shell, and

this is multiple of 7 subtract o, and we get the same repeated. found that the characteristic sculpturing on the outside was still For the seventeenth subtract 6, and remember that when the clearly visible.

result is negative we must replace it by the defect of the correThis egg, then, hatched out after being laid for about seven

sponding positive number from 7, and we get teen months (from about July 1891 to about the end of Decem 3 6 6 2 4 0 2 5 1 2 5 1 ber 1892). I cannot believe that under natural conditions the embryos take so long to develop. At any rate it now appears

Example.— Battle of Hastings, Oct, 14, 1066. certain that the larger Victorian Peripatus lays eggs which may

À £ 6CD Sum. Remr. hatch alter a lapse of a year and five months.

14 2 66 16 98 0 Saturday,

ARTHUR DENDY. The University of Melbourne, February.

Execution of Charles I., Jan. 30, 1649,

B C D Sum. Remr.

30 3 49 12 = 94 94 3 Tuesday. A Simple Rule for finding the Day of the Week corre

H. W. W. sponding to any given Day of the Month and Year,

A RULE was lately mentioned to me by a friend for finding, almost by inspection, the day of the week for any given year

“Roche's Limit.” and day of any month in that year, during the present century.

With reference to Prof. G. H. Darwin's notes (NATURE, The basis of the rule is so obvious, when once the rule is stated, as to require no demonstration, but it struck me as so ingenious

March 16, p. 460) on the investigations of M. Roche as to the as to be worth while communicating it to you in case you

smallest distance from its primary at which a satellite can exist, deemed it worthy of insertion. I also append a very easy

does not the distance given-viz. 2'44 times the radius of the method of extending the rule to any date subsequent to the

primary-refer to the case of the satellite having the same introduction of the Julian intercalation either in the past or

density as its primary? In Note 3 Prof. Darwin warns the future, except indeed for the eighteenth century, in which the

reader that Roche's limit depends, to some extent, on the

density of the planet. Suppose the density of the planet to introduciion of the new style requires a special treatment.

remain the same while that of the satellite is taken at double. The nineteenth century rule above alluded to is this. Each

In this case the tidal or differential influence of the planet on of the 12 months has its special numerical constant, thus:

the two halves of the satellite will have doubled, while the Jan. Feb. Mar. Ap. May June July Aug. Sept. Oct. Nov. Dec. gravitational attraction of the two halves of the satellite on

3 6 6 2 5 0 2 3 1 3 6 1 each other will have become fourfold ; and generally, the power Write down four columns thus

of the planet to pull the satellite asunder will be inversely as

the density of the satellite, and directly as the density of the A i B i C i D

planet. Under A enter day of month, under B constant for that An alteration of the size of the satellite does not much affect month, under C year of century, under D greatest multiple of 4 the question, because both forces are thereby equally altered, so in the year of century.

| long as the satellite is very small in comparison with its distance Add together the numbers under these heads, divide by 7, from the planet. and the remainder is day of week; except that in Leap Year Seeing that the tidal or differential influence of a planet on I must be subtracted for any day before February 29.

its satellite is inversely as the cube of their distance aparı, per

haps it would be correct, as far as gravitational influence alone Example.- June 18, 1815 (Battle of Waterloo) :

is concerned-to state the limit at which a satellite can exist as A B C D Sum. Remr.

being equal to 2-44 R X 18 0 15 3 36 3 1 Sunday. February 1, 1892:

where

R = the radius of the planet,
A B C D Sum.

D = the density of the planet,
Remr.
6 92

d = the density of the satellite.
23 122 122
3 Sunday

As an interesting case of the same problem from a different Subtract 1 for Leap Year before February 29. Ans.-3 -1= 2 or Monday. point of view, suppose two very small equal spheres in contact, December 25, 1892:

and a third much larger sphere placed in line with their A B C D Sum.

centres, all three having the same density; then, when

the distance of the point of contact of the small spheres 25 1 92 23 141

1 Sunday

from the centre of the large one is 2.52 times the radius

of the large one, the attraction of the two small spheres for each To extend the rule to any future century, we have only to other just balances the differential influence of the large one alter the monthly constants, adding 5 to each for each added

tending to draw them asunder. The effects of variation in density century after the present, and i for each century, an exact and size being the same in this case as in the former. multiple of 4, in the interval.

It would probably be interesting to many of your readers to Thus for the thirty-first century. Number of added centuries have Prof, Darwin's views as to whether it is a reasonable supis 12, and there are 3 centuries, succeeding multiples of 4 position that a small satellite, such as Jupiter's fifth, is likely to (twenty-first, twenty-fifth, and twenty.ninth). Therefore add have the same density as Jupiter ; and whether the meteorites 5 X 12 + 3 =63, or omitting multiples of 7, add o.

| forming Saturn's ring are likely to be of so small density as

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Saturn ; as it would appear that without making some such the introduction of the function to Laplace, it is difficult to supposition, no definite limit can be fixed.

compare the dates. I am at present unable to refer either to Applying this supposition to the sun, with reference to the memoir of Lagrange or to the treatise of Mr. Bianco. meteoric swarms, we have 2'44 times the sun's radius, taken at

E, J. ROUTH. 433,000 miles, or 1,056,520 miles as the distance at which the sun would prevent the meteors coalescing to form a planet. In Note 3 Prof. Darwin states this at one-tenth of the earth's dis

Van't Hoff's "Stereochemistry.” tance from the sun, probably by inadvertence.

G. R.

The review of the above by “F. R. J." in NATURE, R. 436, raises some important points in connection with this

peculiarly fascinating branch of chemical science. In referring The Ordnance Survey and Geological Faults. to the recent ingenious and attractive theory of P. A. Gaye, In view of the re-survey of the United Kingdom, it seems to that the numerical value of optical activity is dependent apon me that if the officers of the Survey were directed to take special

the relative masses of the four groups attached to the asymonotice of the levels of the former survey on both sides of great metric carbon atom, and which carries with it the corollary that geological faulls, and to compare these levels now so as to as is two of these lour groups are of equal mass the rotatory power certain if any appreciable relative change had taken place during will cease, your reviewer states that Guye “was unable to verily the forty or fifty years since the first survey, valuable information

this view in all strictness.” I think, however, that he hardly as to the motion of these faults, if any, might be obtained. emphasises sufficiently that this important corollary has in every

This idea is mainly suggested to me by the fact that in this case, when put to the test of direct experiment, broken down neighbourhood a great fault intersects the Old Red Sandstone | As far as I am aware, there is not a single instance of an asymclose to its contact with the Highland schists, it has been traced metric carbon atom attached to four groups qualitativiy from Stonehaven on the east coast to Loch Lomond on the west, distinct, being sound optically inactive in consequence of two of and seems to give remarkable evidence of being, at least to a those groups being quantitatively equal in mass. Indeed some certain extent, in motion. The village of Comrie, famous for its such substances are not merely active but powerfully so. Tbe “ earthquakes," is situated on this fault, and the earthquakes” reviewer considers that this inadequacy of Guye's theory is are as lively as ever. In the valley of Strathmore farmhouses palliated by the alleged fact that the amount of rotatory power of placed in the proximity of this great dislocation are, or were, the esters of an active acid is determined by the weight of the celebrated for being “haunted,” on account of the noises and alkyl.group. This point, which is one of the cardinal pillars of tremors by which the inhabitants are from time to time Guye's theory, I have recently put to the test or actual experialarmed.

ment, by measuring the rotatory power of a number of the esters Most, if not all, British “ earthquakes" have been, I think, of active glyceric acid, which have been prepared by Mr. J. wisely attributed to similar causes.

MacGregor and myself. In this investigation we found the most Of course fifty years is a very minute part of the history of one | extraordinary verification of Guye's theory, as far as the optical of these old faults, but if the data of the Ordnance Survey be so / properties of the normal series of methyl, ethyl, and propyl accurate as is usually supposed, some trace of shifting might glycerates were concerned; with the appearance of isomerista, possibly be discovered if the necessary observations were made. | however, this regalarity ceases, thus the isopropyl glycerate has Newport, Fife, March 18.

JAS. DURHAM

a markedly lower rotation than the normal one, whilst the normal and secondary butyl compounds have 3

lower rotation than the isobutyl ester. Nor are these differThe Discovery of the Potential.

ences consistently explicable by taking into consideration the MR. E. J. Routh has lately published a most valuable

interatomic distances, as measured by atomic volume, for the "" Treatise on Analytical Statics," I quote from the second

molecular volume of the normal propyl glycerate with its greater volume, p. 17, the following note :

rotation is less than that of the isopropyl compound with its “The earliest use of the function now called the potential, is

smaller rotation, whilst the molecular volumes of the isobutyi due to Legendre in 1784, who refers to it when discussing the

and secondary butyl glycerates are almost exactly equal, although attraction of a solid of revolution. Legendre, however, ex

the rotation of the former is much greater than that of the pressly ascribes the introduction of the function to Laplace, and

latter. quotes from him the theorem connecting the components of

The reviewer, in referring to the rotation exhibited by the attraction with the differential coefficients of the function. The

salts of active acids, states that in the case of tartaric acid all the name, Potential, was first used by Green," etc.

salts“ display in solution the same rotatory power, irrespective From this note it appears that the discovery of the potential

of the atomic weight of the metal," and is apparently satisfied tha! must be attributed to Laplace. This is a wrong opinion, and

“the clue to this anomaly is furnished by the electrolytic theory some fifteen years ago Baltzer proved that the introduction of

of of Arrhenius,” according to which " it is the ion CO (CHOH), the function is due to Lagrange (" Zur Geschichte des Poten

CO, which is alone responsible for the rotation.” The reviewer tials,” in Journal für die reine und angewandte Mathematik, vol. |

has in this endorsed the method of special pleading adopted by 1xxxvi. p. 213, 1878). Some historical documents in favour of

the advocates of this theory, in wbich the metallic tartrates have Lagrange's priority have been found, by the writer of these lines,

been summoned as witnesses, whilst only the testimony of those in Todhunter's " History of the Mathematical Theories of

favourable to the theory has been admitted. Thus one of the Attraction and the Figure of the Earth," and collected in a note

commonest of the metallic salts of tartaric acid-tartar emeticat the end of vol. i. of his work, “Il Problema Meccanico della

has a rotation which differs entirely from that of the other tar Figura della Terra " (Torino, 1880), where a full account of the

trates, and thus conclusively negatives the dogma that the rotaearly history of the potential is given, with numerous biblio

tion of the solutions of metallic salts is independent of the graphical indications. OTTAVIO ZANOTTI BIANCO.

particular metal which has replaced the hydrogen of the acid. Private Docent in the University of Turin,

Fresh light has been thrown on this point in the course of an March 21.

investigation, which I have recently carried out with Mr. Apple

yard on the rotatory power of the metallic salts of active glyceric The historical note on p. 17 of my "Statics" is chiefly founded acid, and which has shown that the specific rotatory power of the on the statements in Todhunter's "History,” and in Thornson and glyceric acid has one value when deduced from the rotations of Tait's "Natural Philosophy.” The references to these two writers its alkaline salts (lithium, ammonium, sodium,'and potassium are given in the note. Both Dr. Todhunter and Lord Kelvin another value when deduced from the salts of the alkaline earths ascribe the introduction of the function for gravitation to Lap. (calcium, strontium, and barium), cand a third from the salts lace, and assert that the name of “ Potential ” was first given to of the magnesium group of metals (magnesium, zinc, and cadit by Green. My own reading, though not so extensive as mium). Now it so happens that almost the only salts of tartaric theirs, had not led me to form any different opinion. In Nichol's acid which have had their rotation determined are those of the “Cyclopædia of the Physical Sciences” the first introduction is | alkaline metals, which also in the case of glyceric acid yield given as due chiefly to Legendre, Lagrange, Laplace, and practically the same rotation. Hence if only the rotations of Poisson. In Chambers's “Cyclopædia" Laplace's name alone is the alkaline glycerates had been determined, the same erroneous mentioned. Baltzer, as cited by Mr. Bianco, mentions the use conclusion would have been arrived at concerning the rotation of the function by Lagrange in the Mém. de Berlin, 1777. This of glyceric acid. Whatever may be the ultimate interpretation is earlier than the memoir of Legendre, but as Legendre assigns put upon these new results, and I prefer for the present to ab

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