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perimeter was very rough. This change in the variation will be required. The authors, however, of the forma: of c with relation to the s lope was found to depend upon do not regard it as final or complete, nor do they clas the hydraulic radius being greater or less than 3'281 feet; for it any mathematical precision ; they only conside: so that c becomes independent of the change in slope that it agrees more closely than any previous formu'i when R approximates to this value, though the actual with the results of recorded observations. The formula value of R at which the modification occurs varies with has naturally been objected to on account of its comthe degree of roughness of the channel. This result is plicated appearance; but the variation due to changed attributed to the conflicting currents and eddies in large slope renders this inevitable; and it has been seen tha: rivers having irregular beds, or in small channels with a simpler formula may be adopted for pipes, and stai very rough beds, which are intensified by an increase in channels with steep slopes; and, moreover, graphical the slope ; whereas, in small streams flowing in confined methods and tables might simplify the calculations : channels with smooth beds, an increased velocity tends to the close of last year, Mr. Robert Manning, Engineer ta dissipate retarding lateral movements. A preliminary the Board of Works in Dublin, presented a new formula

7 a+

to the Institution of Civil Engineers of Ireland, which, in form adopted for the value of c was

its general form, is hardly less complicated than that ai

where I+

Messrs. Ganguillet and Kutter. This formula is

JR a + replaces y in the original formula, and an = x, or

= n1$${R} + 0-22 (R

Oʻ15m) }; *= ny – 1, in which a is a constant with value 41-66 in where n is the coefficient of roughness, g the force on English measures ; 1 is anot her constant, equal to VR gravity, and m the height of the barometric column when R has the special value 3:281 referred to above, mercury. Mr. Manning puts it forward as simpler and and therefore 1*811 ; and n is the coefficient of rough- better than the other, and claims for it, in a simplified ness, varying, according to the state of the channel, from form, a closer approximation to the mean of the result: 0'009 to 0'040. The above value of c suffices for the flow of seven of the best known formula than any other in pipes and other small channels with steep slopes, Actual observations, however, form a surer basis up owing to the small influence of a variation of slope on the which to establish a general formula than the resuks af coefficient c in such cases; but for ordinary channels previous formulæ ; and it is upon a close concordance wii allowance has to be made for variations in slope, necessi- very varied and accurate observations that any genes tating the introduction of another variable factor into the formula must claim acceptance. Whatever position mas expression for c. The final shape given to the value of c in the future be assigned to the formula of Messrs. Ganby Messrs. Ganguillet and Kutter, in their general guillet and Kutter, their work marks a notable step i 1

advance, and must rank with the researches of Messrs. +


Darcy and Bazin, and Messrs. Humphreys and Abbot. as formula, was

where m = 0'0028075, a record of important hydraulic investigations; and the +

translators have performed a valuable service in placing S

VR for English measures, is a constant of a hyperbola em- clearly before English readers the successive steps by ployed in constructing the formula. The general formula, which this general formula has been established. accordingly, became, for English measures

+ 416+

V =


Der Kompass an Bord : Ein Handbuch für Fishrer sy ( *)

eisernen Schiffen. Herausgegeben von der Direktion S NR

der Deutschen Seewarte. (Hamburg: L. Friederichsen where V is the mean velocity in feet per second, which and Co., 1889.) multiplied by the cross-section would give the discharge THE important subject of the nagnetism of iron ships

. The main interest of the book consists in the clear has, during the last fifty years, received marked attention exposition of the several steps by which the formula was in England from eminent men of science, attended with reached ; and even if at some future time, by the aid of most valuable results for the safe navigation of our Royai fresh observations and more accurate experiments, the and mercantile navies. formula should be superseded by a more comprehensive During the last thirteen years this same subject haz and exact one, the merit of this work as an elaborate been one of continuous inquiry at the German Nava scientific investigation for a general empirical formula Observatory in Hamburg, and papers have been publisher must always remain ; and the book would deserve to be from time to time in the annual report of that institution consulted on this ground alone. The formula depends showing what had been accomplished. Combining che entirely upon the exactness of the observations upon results of this work with those obtained from the extensvt which it has been based. Mr. Révy has questioned the ac- literature chiefly produced in England, Dr. Neumier. curacy of the Mississippi experiments, owing to the use of the Director of the Observatory, has compiled the preses double floats ; and if fresh investigations should establish work for the use of officers commanding the iron ships of the inaccuracy of any of the observations made use of, or the German mercantile navy. if further experiments should extend the scope of the Of the six chapters into which the work is divided, the inquiry, or bring new facts to light, a modified formula first is devoted to information on the magnetism of iron



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S 0'00281 n

and steel, terrestrial magnetism, and the means of has a chapter devoted to it, containing information which obtaining the three magnetic elements.

should be of value both to the captains of ships and comIn the second chapter, the various modern forms of the pass adjusters. It is illustrated by many examples. mariner's compass, and instruments for adjusting com Values of the coefficients v and v', representing the passes without sights, are described with illustrations. temporary deviation caused by running on a given course There is much here which should be of value to com- for some days, are given for a number of vessels of difmanders of ships anxious to know as much as possible ferent types, steam and sailing. They clearly show the of their best friend in navigation.

navigator of a new ship the need of caution when altering It is, however, to be regretted that in some particulars course, and some idea of the amount of change of deviaboth text and illustrations belong to the past, for in Fig. tion he may expect; whilst it should be understood that 38 an imperfect idea is given of Sir W. Thomson's com- no careful seaman would fail to learn and note the pecupass. The drawing was correct for 1877, but important liarities of the iron affecting his ship's compasses from improvements were made ten years ago in the substitu- personal observation under the varied circumstances tion of the wire grummet suspension for india-rubber, a experienced during each voyage. change attended with marked success in vessels propelled: A corrector for the deviation caused by sub-permanent and severely shaken by powerful engines ; also, in 1881, magnetism has yet to be discovered. the adoption of a total reflection prism in the azimuth Taking a general view of this book, it may be described mirror instead of an ordinary piece of looking-glass. as calculated to provide good practical information for

Prominence is given to the Hechelmann compass card, the officers of the German mercantile navy, as well as which is intended to combine the principles of the a certain amount of a theoretical nature for those inclined Thomson card (which consist chiefly of a long period / to learn something of a ship's magnetism from a higher of oscillation and great lightness), with a much greater standpoint. magnetic moment in the Thomson-Hechelmann card, as The maps of the three magnetic elements provided at it may be termed. The chief difference in these cards the end of the book are given for the epoch 1885, and on bes in the arrangement of the needles, Hechelmann's a larger scale than those usually provided in hand-books. idea being to suspend more powerful needles than The accompanying map of values of the secular change Thomson's near the circumference, thus bringing the is somewhat open to criticism as regards the figures reweight as far as possible from the centre of the card to corded in the Red Sea, Bombay, East Indies, and Ausproduce a slow period.

tralia. This, however, will not prove of any detriment In bringing powerful needles so near the circumference, to safety in practical navigation. it is easy to see that something has been lost by Hechel The difficulties connected with the compass in warmann when the quadrantal deviation is to be corrected as ships, with their armoured deck, thickly-plated sides, and it should be-a correction so perfectly accomplished by conning-towers, are not treated of, and their officers must Thorson. The greater weight of the card, too, tends to look elsewhere for the special information they require ; increase friction at the cap and pivot. Under these con- still, there is much to be found in this book that will siderations the Thomson-Hechelmann card can hardly be serve their purpose. considered equal to the modern Thomson. In tbe next chapter, which treats of the magnetism of

OUR BOOK SHELF. ships and the resulting deviation, it is satisfactory to find that the different kinds of magnetism which careful Library Reference Atlas of the World. By John Barthoinvestigation has shown to exist in modern vessels are

| lomew, F.R.G.S. (London: Macmillan and Co., 1890.) specially mentioned. These are-

The recognition of the intimate connection that exists

between physiography and geography is made very (1) Permanent magnetism.

| manifest, in all the atlases published during the last few (2) Sub-permanent (termed also retentive) magnetism. years, by the insertion of maps indicating the physical (5) Transient magnetism.

features of the earth's surface. These definitions are accompanied by a footnote stating We are in an eminently utilitarian age, and a collection that in the English text-books on deviation no difference of maps, to meet the requirements of the day, must serve is made between permanent and sub-permanent mag- more purposes than that of a mere index to the positions netism, but that the two are combined under the express of importance in commercial geography, and the dis

of places; it must represent the most permanent features sion sub-permanent. This is perhaps rather hard upon tribution of commodities as explained by the sciences some English books, where, by careful reading, it will be of physics, geology, meteorology, biology, &c., or collecfound that the distinction is really made, but, it must be tively by physiography. The elegant work before us confessed, with a want of that clearness of division satisfies all these requirements, it is as complete as it is which is important to sound knowledge. Readers of

a trustworthy atlas of modern geography, and will be

equally appreciated by the student, the business man, the papers published by the Royal Society, and more and the general reader. recently by the Royal United Service Institution, will The atlas contains 84 maps, and amongst them we find find that the division of a ship's magnetism into the plates delineating, drainage areas, ocean currents, prethree kinds mentioned above is strongly insisted upon. vailing, winds, rainfall, temperature, climate, and com

A complete analysis of the deviations of any given commercial features. A characteristic of the pass in a ship, and of the changes which take place on British Empire, eighteen plates being given of the United

the large number of maps that have been devoted to the à change of latitude, is necessary before a satisfactory Kingdom alone. India is completed in eight plates, the compensation of the deviation by magnets and soft iron Dominion of Canada is very completely represented in can be made. In the" Compass on Board,” this analysis seven plates, and the mapping of all the British possessions

has been carried out on the same elaborate scale. After be as well to recall the belief of one whose judgmeni vu the British Empire, special prominence has been given without weight, and to give some of the evidence on which the to the United States, whilst all the other countries of belief was founded. the world have been treated in a very comprehensive

In the first chapter of the "Origin of Species " ( 8 of the manner. The general reference index comprises the sixth edition), Mr. Darwin says, respecting the inherited effo. names of 100,000 places contained in the maps, and for has had a more marked influence"; and he gives as instances

of habit, that " with animals the increased use or disuse of par" British names it is the most complete ever published. changed relative weights of the wing-bones and leg-bones of 4 One matter of regret, however, is that the places on some wild duck and the domestic duck, and, again, the droping ears of the maps are not obviously visible because of the of various domestic animals. Here are other passages laica bright and superabundant colouring used to indicate the from subsequent parts of the work :divisions of a country, for, generally speaking, these “I think there can be no doubt that use in our dome. divisions are better represented by coloured lines. The animals has strengthened and enlarger certain parts, and dist less masking there is, the more distinct must places diminished them; and that such modifications are inherited' appear, and therefore the purpose of an atlas will be the (p. 108). And on the following pages be gives five further better served. This is, however, but a minor point. The examples of such effects. “Habit in producing constitution atlas is an excellent one, it is complete and accurate, and diminishing organs, appear in many cases to have


peculiarities, and use in strengthening and disuse in weakers contains all the results of recent exploration and geographical research, and is issued at a moderate price; its potent in their effects" (p 131). “When discussing special

cases, Mr. Mivart passes over the effects of the increasel we addition to every library therefore is a thing to be desired. and disuse of parts, which I have always maintained to be higtig The Bala Volcanic Series of Caernarvonshire

and As- tion at greater length than, as I believe, any other wnie

important, and have treated in my Variation under Domestic sociated Rocks; being the Sedgwick Prize Essay for (p. 176). "Disuse, on the other hand, will account for the bu 1888. By Alfred Harker, M.A., F.G.S., Fellow of St. developed condition of the whole inferior half of the body, I John's College, and Demonstrator in Geology (Petro- cluding the lateral fins ” (p. 188). "I may give another instan.. logy) in the University of Cambridge. (Cambridge : of a structure which apparently owes its origin exclusively to 4 University Press, 1889.)

or habit” (p. 188). "It appears probable that disuse has been In this useful little work, Mr. Harker has given an the main agent in rendering organs rudimentary" (pp. 400-101. admirable résume of the results which have, up to the have, in some cases, played a considerable part in the malilia

“On the whole, we may conclude that habit, or use and disae, present time, been arrived at by the study of the ancient tion of the constitution and structure ; but that the eñects have igneous rocks of North Wales. Besides summarizing the often been largely combined with, and sometimes orermestere! work of the late John Arthur Phillips and E. B. Tawney, by, the natural selection of innate variations" (p. 114). of Prof. Bonney, Mr. Rutley, Mr. Cole, Mr. Teall, Mr. In his subsequent work. “The Variation of Animals and Waller, Miss Raisin, and others who have written on the Plants under Domestication," he writes :petrography of the district, he has added many new and “The want of exercise has apparently modified the proper often judicious notes on the rocks in question. A number tional length of the limbs in comparison with the body" [r of fresh analyses, and the description of hitherto unrecog rabbits] (p 116). "We thus see that the most important au nized varieties of rocks and minerals, raise the work complicated organ [the brain) in the whole organisation out of the category of mere compilations; and the excel- subject to the law of decrease in size from disuse" (s. 120). He lent classification and arrangement of his materials make remarks that in birds of the oceanic islands " not persecuted to the book one eminently useful for purposes of reference caused by gradual disuse." After comparing one of these, the

any enemies, the reduction of their wings has probably beta It is unfortunate that it has no index, though the "table water-hen of Tristan D'Acupha, with the European water-hen, of contents,” which is very full and carefully paged, and showing that all the bones concerned in flight are sınaller, causes the want to be less felt than it otherwise would he adds :-*Hence in the skeleton of this natural species neatir be. Mr. Harker classifies the districts of Caernarvon- the same changes have occurred, only carried a little further, u: shire in which volcanic rocks are found as the Eastern, with our domestic ducks, and in this latter case I presume di North-Western, and Western, the latter consisting of the one will dispute that they have resulted from the lossenesi use of Lleyn peninsula. He groups the types of rocks repre- the wings and the increased use of the legs" (pp. 286-871 " A: sented under the headings of "rhyolitic lavas," " nodu- with other long-domesticated animals, the instincts of the sall lar rhyolites," "acid intrusives," " intermediate rocks," moth have suffered. The caterpillars, when placed on a molberry “diabase sills and basalts,” and other basic intrusions." the leaf on which they are feeding, and consequently fall dowo.

tree, often commit the strange mistake of devouring the base The work concludes with a “review of vulcanicity in but they are capable, according to M. Robinet, or again crawlin' Caernarvonshire,”

, in which we find discussions of the up the trunk. Even this capacity sometimes fails, for 1. Martenrelation of the volcanic eruptions to the earth-movements placed some caterpillars on a tree, and those which fell were no that took place at the period of their occurrence, the suc- able to remount and perished of hunger; they were even cession of lavas in the district, and the evidence in favour capable of passing from leaf to leaf” (p. 304). of their submarine origin. The book is admirably Here are some instances of like meaning from vol. ii. :printed, and is illustrated by six very clearly-drawn "In many cases there is reason to believe that the lesened us sketch-maps. The essay is worthy of the memorial in of various organs has affected the corresponding pares in the or connection with which it appears, and is creditable to the spring. But there is no good evidence that this ever follows ma University under whose auspices it is issued ; and higher the course of a single generation. . . : Our domestic fowls praise than this it would be difficult to give to any work ducks, and geese have almost lost, not only in the individual bat of the kind.

in the race, their power of flight; for we do not see a chickes when frightened, take flight like a young pheasant. . . . With domestic pigeons, the length of sternum, the prominence of its

crest, the length of the scapulæ and furcula, the length of the LETTERS TO THE EDITOR.

wings as measured from tip io tip of the radius, are all reduce [The Editor does not hold himself responsible for opinions ex. kindred diminutions in fowls and ducks, Mr. Darwin add

relatively to the same parts in the wild pigeon." After detailing pressed by his correspondents. Neither can he undertake "The decreased weight and size of the bones, in the foregang to return, or to correspond with the writers of rejected cases, is probably the indirect result of the reaction of the manuscripts intended for this or any other part of Nature, weakened muscles on the bones" (pp. 297-98). "Nathustus ha No notice is taken of anonymous communications.]

shown that, with the improved races of the pig, the shorten The Inheritance of Acquired Characters.

legs and snout, the form of the articular condyles of the occiput,

and the position of the jaws with the upper carine teeth project WITHOUT expressing any opinion upon the question recently ing in a most anomalous manner in front of the lower canine discussed in your columns under the above title, I think it may may be attributed to these parts not having been fully exercise!

These modifications of structure, which are all strictly was more inclined to attach importance to Lamarck's theory in inherited, characterize several improved breeds, so that they the later editions of the "Origin of Species,” the anti-Lamarckians annot have been derived from any single domestic or wild stock. are convinced that it is conducive to the progress of knowledge Wah respect to cattle, Prof. Tanner has remarked that the lungs to reject that theory altogether until (if ever) it is placed on a and liver in the improved breeds are found to be considerably solid basis of observed fact; and in the meantime to try if it is seduced in size when compared with those possessed by animals possible to explain the cases which seem most favourable to Having perfect liberty.' : . The cause of the reduced lungs in Lamarck's view by the application of Darwin's own theory. highly-bred animals which take little exercise is obvious" (pp. It is essential for those who are not thoroughly familiar with 299-300). And on pp. 301,

302, and 303, he gives facts showing Darwin's writings to note that this does not involve a rejection the effects of use and disuse in changing, among domestic animals, of the conclusion that the action of external conditions upon a the characters of the ears, the lengths of the intestines, and, in parent may be such as to modify the offspring. That is an SYLrious ways, the natures of the instincts.

important part of Mr. Darwin's own theory, and, as I recently Clearly the first thing to be done by those who deny the pointed out in Nature, it is to such action of the environment inlueritance of acquired characters is to show that the evidence upon the parent that Mr. Darwin attributed the origin of those Mr. Darwin has furnished by these numerous instances is all congenital variations upon which natural selection acts. This worthless.

HERBERT SPENCER. disturbance of the parental body (I compared it to the shaking

up of a kaleidoscope), and with it of the germs which it carries,

resulting in "sporting" or "variation" in the offspring, is, it LET me remind the readers of NATURE that the discussion should hardly be needful to state, a totally different thing to the which has been going on in these columns, between the Duke of definite acquirement of a structural character by a parent as the Argyll and Mr. Thiselton Dyer, arose out of a reference in Mr. result of the action upon it of the environment, and the transWallace's book on "Darwinism” to the dislocation of the eyes mission to offspring of that particular acquired structural character. of Alar-fishes. Two views have been expressed as to the origin I am not concerned to inquire here whether, or how far, Prof. of this arrangement-the one endeavouring to explain it as a Weismann's theory of the continuity of the germ-plasm admits of case in which a "sport" or congenital variation, had been the action of external forces on a parental body in such a way as to selected and intensified; the other attributing it to the direct disturb the germ-plasm and induce variation. Prof. Weismann acuon of the muscles of ancestral flat-fishes which had pulled can very well defend his own views. All that I am concerned the eye out of its normal position, the dislocation thus estab-with--and that quite independently of the conclusions of Prof. lashed being transmitted to offspring, and its amount increased Weismann-is whether it is or is not reasonable, useful, or indeed isy like action in each succeeding generation. In common legitimate, to assume the truth of Lamarck's second law, in the with Mr. Wallace and other naturalists, I spoke of this latter absence of any direct proof that any such transmission as it wypothesis as one of transmission of an "acquired character." postulates takes place. Those who think Lamarck's second law I he term "acquired character" was clearly enough defined by to be true have been urged to state (1) cases in which the transthis example ; it has been used in England for some years, and mission of acquired characters is directly demonstrated, or (2) 11 equivalent in German (crworbene Eigenschaften) has been cases in which it seems impossible to explain a given structure defined and used for the purpose of indicating the changes in except on the assumption of the truth of that law. If they fail to 3 parent referred to by Lamarck in the following words do this, they are asked to admit that Lamarck's second law is,

** Philosophie Zoologique," tome i. p. 235, édition Savy, unproven and unnecessary. 1873) :

The response which has been made to this attempt to arrive at ** Première Loi.--Dans tout animal qui n'a point depassé le facts is beside the mark. Mr. Cope writes to NATURE merely terme de ses developpements, l'emploi plus fréquent et soutenu asserting, "If whatever is acquired by one generation were not 4'an argane quelconque, fortifie peu à peu cet organe, le transmitted to the next, no progress in the evolution of a character Arveloppe, l'agrandit, et lui donne une puissance proportionnée could possibly occur, "--an opinion peculiar to himself, and cer- la durée de cet emploi; tandis que le défaut consant d'usage tainly one which cannot be taken in place of fact. The Duke of te tel organe, l'affaiblit insensiblement, le détériore, diminue Argyll then "interpolates” (to use his own word) a general rogressivement ses facultés, et finit par le faire disparaitre. statement of his beliefs, and in the last of his letters a statement

** Deuxième Lei.-Tout ce que la nature a fait acquérir ou of “what his position is.” We really are not concerned in this querdre aux individus par l'influence des circonstances où leur matter with beliefs or positions. We want well-ascertained facts ace se trouve depuis longtemps exposée, et par conséquent par and straightforward reasoning from facts. The Duke of Argyll l'influence de l'emploi prédominant de tel organe, ou par celle has not assisted us. When on a recent occasion he was asked to *nn stefant constant d'usage de telle partie, elle le conserve par cite an instance of what he called "a prophetic germ” in the la generation aux nouveaux individus qui en proviennent, adult structure of a plant or animal having, in his opinion, such pourvu que les changements acquis soient communs aux deux claims to this title as he had ascribed to the electric organ of

ou ceux qui ont produit ces nouveaux individus." skates, the Duke was unable to reply. He wrote as a substitute The meaning of the term "acquired characters" is accord- something about embryological phenomena, which had nothing ingly perfectly familiar to all those who have any qualification to do with the case. He has not yet ventured to stake his ofifor discussing the sabject at all. It is used by Lamarck, and has asserted right to offer an opinion upon zoological topics, on the been used since as Lamarck used it. Naturalists are at present reception which his attempt to deal with the details of a parnoierested in the attempt to decide whether Lamarck was justi- ticular case of organic structure would obtain : in this, I think, he bed in his statement that acquired changes are transmitted from is wise. the parents so changed to their offspring Many of us hold that The Duke similarly tries to evade the appeal to facts when he he was nol; since, however plausible his laws above quoted may is pressed by Mr. Dyer to state cases of the transmission of appear, it has not been possible to bring forward a single case acquired characters. In doing so, however, he has, it must be m wbuch the acquisition of a character as described by Lamarck admitted, revealed an astonishing levity. He answers (par. 9 and its subsequent transmission to offspring have been con of his letter) that in all domesticated animals, and especially in clusively observed. We consider that, until such cases can be dogs, we have constant proof that many acquired characters may produced, it is not legitimate to assume the truth of Lamarck's become congenital. This is mere assertion; we require details. second law, We admit, of course, the operation of the environ. It is maintained, on the contrary, by anti-Lamarckians that the ment and of use and disuse as productive of " acquired charac- whole history of artificial selection, and of our domesticated Ten"; but we do not find any evidence that these particular animals, furnishes a mass of evidence against the theory of the characters so acquired are transmitted to offspring. Accordingly transmission of acquired characters, since if such cases occurred it has been held by several naturalists recently (whom I will call they would be on record, and moreover would have been utilized

ne anti-Lamarckians, and among whom I include mysell) that it by breeders. qe nece-sary to eliminate from Mr. Darwin's teachings that small The subsequent proceeding of the Duke is almost incredible. amount of doctrine which is based on the admission of the In the following paragraphs of his letter he gives up his convalidity of Lamarck's second law. As everyone knows, Mr. tention that acquired characters are transmitted, coupling his Tarwin's own theory of the natural selection of congenital varia retreat with unwarrantable charges against those who have 1sons in the struggle for existence is entirely distinct from lately raised the question as to whether this is the case or Lanarck's theory, and the latter was only adınitted by Darwin not. He correctly states what is meant by the term “acquired as being possibly or probably true in regard to some cases, and of characters," and declares that this meaning has been expressly mninor importance. Although Darwin expressly states that he l invented for the purposes of the present discussion by "for

tuitists," and is "irrational.” A more baseless charge was never Du Bois told me, that Van der Waals had given numerical er yet made in controversy, nor a more obvious attempt to alter the mates of the value of Laplace's K. I had long known, from terms of discussion so as to give some appearance of plausibility the papers of Clerk-Maxwell and Clansius, the main features * to a lost cause. The Duke, in fact, now at length tells us that Van der Waals' investigation. But I also knew that Maxweil he does not mean by "acquired characters ” what we mean. had shown it to be theoretically unsound, and that Claus Why then did he "interpolate” his remarks on the subject and had taken the liberty of treating its chief formula as a mere make use of the term ?

empirical expression, by modifying its terms so as to make i If the meaning which the phrase has for the scientific world better fit Andrews' data. This paper of Clausius is apparently generally be insisted upon, we are now, it appears, to understand unknown to my critic, as is also my own attempt to establish that the Duke of Argyll agrees with us : what we mean by (on defensible grounds) a formula somewhat similar to tha: * acquired characters ” are not, he admits, shown to be trans- Van der Waals. mitted.

(2) I said nothing whatever about the "Volume of Matter in “Fortuitists,” the Duke says, “have invented a new verbal unit volume of Water." Hence the critic's statement, " Pri definition of what they mean by 'acquired.'” I have shown at Tait's value is 0-717," is simply without foundation. the commencement of this letter that the term "acquired " is used I merely said that the empirical formula to-day as it was by Lamarck. To the Duke this meaning is "new"-because he has either never read or has forgotten his

Alv - a) = constant, Lamarck. If this be so, the Duke has been writing very freely if assumed to hold for all pressures, shows that a is the volume about a subject with which his acquaintance is very small. The when the pressure is infinite. I still believe that to be the alternatives are as clear as possible : either the Duke of Argyll case. If not, Algebra must have changed considerably since I knew the significance of the term “ acquired characters ” as em | learned it. ployed by Lamarck, in which case it would have been impossible

My critic speaks of a totally different thing (with which I wa that he should charge those whom he calls “fortuitists" with not concerned), which may be a/4 or al4/2, or (as I thuak. having invented a new verbal definition of what they mean by more plausible) a/8. But he says that liquids can be compresor " acquired"; or he did not know Lamarck's use of the phrase, to 0-2 or 0-3 of their bulk at ordinary temperatures and pre and was therefore not qualified to offer an opinion in the dis

sures. I was, and remain, under the impression that this cund cussion, nor to press bis " beliefs” and “position " upon public be done only at absolute zero, and then no compressions attention.

required. I have no time and you have no space to devote to a full

There are other misrepresentations of my statements, que exposure of the character of other assertions made in the Duke grave as those cited. But it would be tedious to examine them of Argyll's "statement of his position " which are as reckless all. I have no objection to a savage review, anonymous ut ni. and demonstrably erroneous as that concerning the meaning of on the essential condition, however, that it be fair. It is die the term "acquired.”

from what I have shown that this essential condition is alreal. Perhaps the most flagrant of these is the assertion that "the But my critic, when his statements are accurate, finds and theory of Darwin is essentially unphilosophical in so far as it with the form of my work. I will take two examples of the ascribes the phenomena of variation to pure accident or fortuity" | kind, and examine them. (paragraph 4). Of course the Duke cannot be acquainted with the

(3) He blames me for not using C.G.S. units. The Center following passage from the “Origin of Species," sixth edition, lenger Reports are, as a rule, written in terms of understandel p. 106 ; but if he has to plead ignorance of the writings not only of Of” nautical men. I wonder what such men would have see Lamarck, but also of Darwin, what is the value of his opinions of me, in their simple but emphatic vernacular, if I had spokea and beliefs on Lamarckism and Darwinism? The words of of a pressure of 154,432,200 C.G.S. units, when I meant whs: Mr. Darwin referred to are these :-" I have hitherto sometimes they call a "ton"; or, say, of 185,230 C.G.S. units, wbo! spoken as if the variations, so common and multiform with meant a “ naut.” organic beings under domestication, and in a lesser degree with

(4) I am next blamed for "mixing units." those under nature, were due to chance. This, of course, is a

I should think that if we could find a formula expressing a wholly incorrect expression, but it serves to acknowledge plainly terms of a man's age, the average rate at which he can rua, sp our ignorance of the cause of each particular variation.

for instance Whatever meaning the Duke may attach to the word

A.x(B - *). "fortuity,” it is mere empty abuse on his part to call the

**+C! later Darwinians “fortuitists," and still less justifiable to insinuate that their investigations and conclusions are not guided by a even my critic would express A in feet per mond, and take xD simple desire to arrive at truth, but by the intention of propping in all the world, insist on expressing * as denoting the went up a worship of Fortuity. It is natural for the Duke to suppose it impossible to write on Darwinism without some kind of theo

seconds in order to prevent what he calls the mixing of logical bias.

This is a case precisely parallel to the one in question. In conclusion, I venture to point out that the Duke of Argyll

Generally, i would remark that my critic seems to have has (1) failed to cite facts in support of his assertions of belief written much more for the purpose of displaying liza ovt in “prophetic germs,” and transmission of acquired cha- knowledge than of telling the reader what my Report coalsus. racters " when challenged to do so ; (2) that he displays ignor

For at least three of the most important things in my kepy? ance of two of the most important passages in the works of are not even alluded to: the compressibility of mercury, ELamarck and of Darwin, whom he nevertheless criticizes, and nature of Amagat's grand improvement of the Manas in consequence of his ignorance completely, though uninten

Desgoffes, and (most particularly) the discussion of the wonul tionally, misrepresents ; and (3) that he has introduced into these ful formula for the compressibility of water given in de columns a method of treating the opinions of scientific men, viz. splendid publications of the Bureau International. by insinuation of motive and by rhetorical abuse, which, though

P. G, Tan. possibly congenial to a politician, are highly objectionable in the arena of scientific discussion.

The last volume of the Challenger Reports contains putenir February 22.

E. RAY LANKESTER. various branches of science. The review which appear &

NATURE was not the work of one writer, and was thereinte Physical Properties of Water,

signed, but I have no desire to avoid taking full respogulub

for the part of which I am the author. As you inform me that my anonymous critic (ante, p. 361) It will be convenient to reply to Prof. Tait in paragi bo does not intend to avail himself of the opportunity I gave him numbered to correspond with his own. (through you) of correcting his misstatements about my Challenger (1) Of course I fully accept Prof. Tait's account of busk Report, I must ask to be permitted to correct them myself. ledge of Van der Waals' theory at the time when his Club, (1)

. There is nothing whatever in my Report to justify the Report was written, but I entirely dissent from home sisteme critic's statement that I "had never heard of Van der Waals' that what he said about it in the Addendum referred to all work . . . till the end of the year 1888." Yet this is made the review was "to the effect " described above. basis of an elaborate attack on me!

It is hardly possible to do justice to my own cue wil What I did say was to the effect that I was not aware, till Dr. quoting freely, but I will compress as much as possitde he

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