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THE

THURSDAY, NOVEMBER 19, 1874

ELIE DE BEAUMONT

HE life of the science of geology has been short; that of many of its illustrious votaries has been long. There still survive a few whose recollections go back to he early triumphs of the science in the days of William Smith and Cuvier. But their number grows rapidly less. One by one the links which bind us personally with the glories of the past are being snapped asunder. The grand old oaks under whose branches the younger saplings have grown up are fast dropping down. Within the last few years we have lost in this country our Murchison, Sedgwick, and Phillips; Austria her Haidinger; Germany her Gustav Rose, Bischof, and Naumann; America her Agassiz, and France her D'Archiac and De Verneuil. To this list we have now to add the well-known name of L. Elie de Beaumont. To the expressions of regret with which the friends and pupils of that father in science have followed his remains to the tomb, geologists in every country will add their sympathy. Those who knew him best have eulogised his love of truth, his piety, and his generous feeling for younger and struggling men of

science.

The name of Elie de Beaumont is chiefly known out of France by its association with two theories-Cratères de soulèvement and the Risau pentagonale --which he espoused and vigorously defended, but neither of which has met with general acceptance, though no one can peruse the writings in which they are developed without admiring the wonderful industry of Elie de Beaumont in the accumulation of facts and the felicitous imagination with which he marshalled these facts in support of the theory to which he had pledged himself. It is not easy for geologists in other countries to understand the vast influence which for nearly half a century he has held in France. We must bear in mind the system of centralisation which controls even scientific enterprise in that country, and the fact that Elie de Beaumont held official posts in Paris which gave him a powerful sway over geological and mining matters, especially such as were under the guidance of the State. Hence it was not merely his great reputation, but his official position, which enabled him for so many years in great measure to control the progress of physical geology in his native country.

This eminent geologist was born in the year 1798. In 1817 he entered the Ecole Polytechnique, where he greatly distinguished himself, leaving it in the first rank for the Ecole des Mines. At that institution he showed a strong tendency towards geological pursuits, and such capacity for their prosecution that he was soon chosen to perform one of the most onerous tasks which had ever been undertaken by the Mining Department of France. The publication of Greenough's geological map of England, and the reception of a copy of it in the year 1822 at the Ecole des Mines, revived a project which political considerations had displaced, of constructing a geological map of France. When the decision to undertake this great work was formed, Elie de Beaumont, with his follow-pupil and future friend and associate Dufrénoy, was selected to carry out the necessary surveys. With VOL. XI. No. 264

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the view of giving them still further training for their task, the authorities sent them over to study the geology of England, particularly the arrangement of the secondary rocks of this country, which by the genius of William Smith had become a type for all parts of Europe. Six months were spent in this preliminary work, some portion of the time being devoted to a careful study of British mines and mining, on which the two young engineers furnished some voluminous and skilful reports. It was the year 1825 before they received orders to begin their surveys. France was separated into two sections, the eastern half being allotted to Elie de Beaumont. The two observers, however, met frequently, and after the main part of their labours was concluded they went over portions of the ground together, so that in the end, agreeing on all main points, they produced a harmonious and magnificent work. In ten years they had completed their surveys. The engraving necessarily occupied some five years more, after which the indefatigable authors produced two large and exhaustive quarto volumes of explanations of the map, wherein the geological structure of their country was well described.

Of all the achievements of Elie de Beaumont, this, his first, is probably that on which his fame will ultimately most securely rest. It was a great work, most conscientiously and skilfully performed, amid difficulties which can only be adequately realised by those who have essayed geological mapping, and who know the nature of the ground over which the French explorer had to trace his lines.

During the twenty-three years (1825-48) which elapsed between the beginning and the completion of the map and its accompanying text, Elie de Beaumont had made his name widely known by other important contributions to science. A few years after the mapping had begun, and while engaged in exploring the high grounds in the east of France, he was struck by the relations which could be traced between the direction of different lines of mountain and the nature and position of the strata along these lines of elevation. In 1829 he published the first sketch of the theory which afterwards grew into the wellknown Réseau pentagonale. He likewise adopted and defended Von Buch's Erhebungs-krater theory, publishing in its support an elaborate essay on the structure of Etna (1836). One of his best essays was published in 1847, "Sur les Emanations Volcaniques et Métallifères," a luminous exposition from the point of view of a cataclysmist of the history of the volcanic phenomena of the globe. One of his best separate publications is his "Leçons de Géologie pratique," a work full of knowledge and research, which may be usefully studied by all who take interest in dynamical geology. It would take some time to enumerate even the titles of his various contributions to the transactions and journals of his day. They include short notes and long memoirs of original research of his own, elaborate reports upon the writings of others (of this style he was a master), instructions to exploring expeditions, &c.; and they are not confined to physical geology, but embrace also the allied sciences-chemistry, mineralogy, and palæontology. One feature which characterises them is the endeavour after exactitude. Their author had a mathematical mind, and sought for mathematical precision in his development of a subject.

Elie de Beaumont in the course of his long career filled many offices of distinction. As far back as 1827 we find him lecturing for his master at the Ecole des Mines, and afterwards succeeding to the chair. In 1832, on the death of Cuvier, he was chosen to fill the only chair of Natural History at the Collége de France. He thus stood at the head of the geological tuition of the country. The mining engineers and others who required geological instruction for State certificates or appointments passed through his hands. His fame likewise attracted many from a distance, so that as a teacher his influence must be regarded as having been very great. Moreover, i became Inspector-General of Mines, member and perpetual secretary of the Academy of Sciences, and was an associate of many of the learned societies of Europe and America. His scientific renown and high personal character led to his being chosen as senator and raised to the rank of Grand-Officier of the Legion of Honour. Full of honours, therefore, he has closed a long life with his faculties unimpaired to the last, and in the midst of the activity which had marked his long and honourable

career.

This is perhaps hardly the place or the time to pass any judgment on the work of the illustrious man who has just gone from among us. His name will ever be associated with the history of geology, linked with those of Cuvier, Brongniart, Dufrénoy, and others who led the way to all that has since been achieved in the geology of France. ARCH. GEIKIE

FLÜCKIGER AND HANBURY'S "PHARMA

COGRAPHIA”

Pharmacographia: a History of the principal Drugs of Vegetable Origin met with in Great Britain and British India. By Friedrich A. Flückiger, Ph.D., Professor in the University of Strassburg; and Daniel Hanbury, F.R.S., Fellow of the Linnean and Chemical Societies of London. (Macinillan and Co., 1874.)

THER

HERE was a stir of anticipation and inquiry amongst pharmacologists when it first became known that Prof. Flückiger and Mr. Hanbury were engaged upon a work of joint authorship. Speculation was busy as to what was to be the nature of the book, to what particular objects it would be directed, what extent of ground it would cover, and so forth. Upon a single point all were agreed, namely, that it would not be one of those composite treatises on drugs - organic and inorganic-therapeutics, pharmacy, and toxicology, enlivened by traditional botany and old-fashioned chemistry, which have passed current amongst us as "Manuals of Materia Medica."

One generation after another of compilers have produced volumes supposed to be suited to the wants of the time, in which the same sort of information has been given, the same errors perpetuated often in almost identical words, until the very term "Materia Medica" has come to be looked upon with suspicion by scientific men. Perhaps the origin of the shortcomings of the general run of such works may be traced to the fact that they have often been written by practising physicians who were lecturers in medical schools, and have been designed primarily as handbooks for medical students. Nor need

it be a matter of wonder that, with no special facilities for acquiring original information as to the history of drugs, and with few opportunities for verifying the statements of others, authors so situated were content to transcribe without examination what had been already recorded as fact, and to devote their better energies to the more purely medical relations of the subject-the aspect of chief interest both to themselves and those for whom they wrote. The question has often been raised, and once at least on very high authority, why the overcharged curriculum of medical study should still be encumbered with Materia Medica; why, in view of the separation which is gradually taking place between the practice of Medicine and that of Pharmacy and of the scientific education now received by the pharmaceutist, such matters as the physical characters sources, and chemistry of drugs should not be referred to those whom they primarily affect.

This, perhaps, is scarcely the place to discuss such questions in detail, but they inevitably present themselves on a comparison of the present book with any of those to which allusion has just been made.

It is generally no very difficult thing to give an intelligible account of a work embodying the results of scientific research. It is not requisite that the knowledge of the reviewer should be co-extensive with that of the author to enable him to form a just estimate of its strong and weak points, or even to exercise the critical faculty where opinions rather than facts are advanced. But the task of introducing suitably a closely printed volume of 700 pages, containing scarcely anything but facts--an unusual proportion of which are stated for the first time, and those which are old assuming a new importance from their fresh verification, the whole given with a condensation of style that refuses page-room to a superfluous word-is not one that can be performed by the ordinary me.hod of summarising results.

The scope of the "Pharmacographia" and the intention of its authors can hardly be better told than by a few extracts from the Preface. After defining the word Pharmacographia as "a writing about drugs," the authors state that "it was their desire not only to write upon the general subject and to utilise the thoughts of others, but that the book which they had decided to produce together should contain observations that no one else has written down. It is in fact a record of personal researches on the principal drugs derived from the vegetable kingdom, together with such results of an important character as have been obtained by the numerous workers on Materia Medica in Europe and America."

Restricting the field of their inquiry by the exclusion of Pharmacy and Therapeutics, "the authors have been enabled to discuss with fuller detail many points of interest which are embraced in the special studies of the pharmacist."

"The drugs included in the work are chiefly those which are commonly kept in store by pharmacists, or are known in the drug and spice market of London. The work likewise contains a comparatively small number which belong to the Pharmacopoeia of India: the appearance of this volume seemed to present a favourable opportunity for giving some more copious notice of the latter than has hitherto been attempted."

Now as to the manner of treatment. A uniform sub

division into sections has been adopted throughout the work. In the first place, "Each drug is headed by the Latin name, followed by such few synonyms as may suffice for perfect identification, together in most cases with the English, French, and German designation.

"In the next section, the Botanical Origin of the substance is discussed, and the area of its growth or 1.locality of its production is stated."

"Under the head of History, the authors have endeavoured to trace the introduction of each substance into medicine, and to bring forward other points in connection therewith, which have not hitherto been much noticed in any previous work.”

"In some instances the Formation, Secretion, or Method of Collection of a drug has been next detailed: in others, the section History has been immediately followed by the Description, succeeded by one in which the more salient features of Microscopic Structure have been set forth."

The next division includes the important subject of Chemical Composition; then follows a section, devoted to Production and Commerce; and lastly, observations, chiefly dictated by actual experience, on Adulteration and on the Substitutes which in the case of certain drugs are occasionally found in commerce, though scarcely to be regarded in the light of adulterants.

"The medicinal uses of each particular drug are only slightly mentioned, it being felt that the science of therapeutics lies within the province of the physician, and may be wisely relinquished to his care.”

The reader must not judge the Preface by the disconnected sentences which have been quoted to serve a particular purpose. Only sufficient has been copied to explain briefly, and as far as possible in the authors' own terms, the general scheme of their work.

The plan, as will be seen, is one of great comprehensiveness, and the execution throughout is of characteristic thoroughness. A single article taken at random from the book would be better evidence than any criticism, of the exhaustive character of the treatment; but unfortunately, considerations of space preclude anything more than a few general remarks suggested by a first perusal.

The investigation of the botanical origin of drugs is one which Mr. Hanbury has made his own, and few writers have set at rest so many debated questions in this division of the subject. Completeness and accuracy of the information now collected is exactly what might have been expected. The student who knows only the British Pharmacopoeia will find much to learn, and something to unlearn, concerning the origin of many common medicinal substances. In some cases the corrections necessary arise merely out of questions of priority in botanical nomenclature, but in others the errors are founded in the wrong identification of the plants. For instance, Fateorhiza palmata, Miers, is the name accepted, for reasons given in the text, for the plant yielding calumba root, rather than the alternative specific terms of the Pharmacopoeias. Oil of cajuput is assigned to Melaleuca leucadenaron, L., whilst in the British Pharmacopoeia and the Paris Codex it is referred to M. minor, DC., and in that of the United States to M. cajuputi, Roxb. Sumbul Root, the botanical history of which in our Pharmacopoeia is stated to be unknown, appears as the product of Euryangium Sumbul, Kauffman, a plant of the natural

order Umbelliferæ. On the other hand, in speaking of the botanical origin of Myrrh, which the Pharmacopoeia, without show of doubt, assigns to Balsamodendron myrrha, Ehrenb., it is stated that "the botany of the myrrh trees is still encompassed with uncertainty, which will not be removed until the very localities in which the drug is collected shall have been well explored by a competent observer." It would be easy to multiply examples, but beyond a passing allusion to Pareira Brava as the root of Chondodendron tomentosum, Ruiz et Pav., a fact determined by Mr. Hanbury's researches, this portion of the subject need not be dwelt upon.

The information given under the head of "History" has a general as well as a technical value. All sorts of writers, ancient and modern, have been laid under tribute; and the glimpses one obtains, not only of the medical but of the domestic employment of drugs in past times, are full of interest.

This running commentary need not be extended to all the headings under which the treatment of each substance is arranged. The term "Substitute" as distinct from "Adulteration," perhaps needs a word of explanation. It is employed to comprise substances occasionally met with in commerce, the product of plants more or less closely allied to the officinal one; for instance, the wood of Quassia amara instead of that of Picrana excelsa, the occurrence of the root of Aristolochia reticulata in place of A. serpentaria, or of the dried plant of Piper aduncum

in lieu of the true Matico.

The notices of Indian officinal drugs have the interest of novelty to European students, but beyond this leave little room for present remark. In course of time some of them may be introduced at home, and in any case, with the amount of communication which exists between England and her Eastern possessions, nothing which concerns the one can be unimportant to the other. Indian medical men are largely drawn from this country, and by them, at least, they will be gratefully received.

The only department of the book which does not yield unalloyed satisfaction is that which refers to "Microscopical Structure." The descriptive paragraphs are, no doubt, as good as words can make them, but mere words are insufficient for the purpose. If anyone doubts this, let him try to construct a drawing of microscopic structure from a description, and then compare it with the reality; or, on the other hand, let him endeavour to identify one vegetable production out of a number closely allied, by means of a mere verbal definition of characters. Either task is difficult at best, sometimes impossible. It is not to our credit that there should be no British work of reference containing a complete series of illustrations of the anatomy of drugs. What is wanted is not so much an elaborate atlas, like that of Dr. Berg, with large, ideal, diagrammatic drawings, suggested by the microscopic appearance of the various vegetable products used in medicine, as a set of figures of characteristic portions of structure presented in a form in which the working student may recognise them. How welcome such an addition to the book would have been from Prof. Flückiger's skilful hand. It is only just to the authors to state that they make no claim for completeness in this division of the work; indeed, they are so fully aware of what is needed, that one might almost indulge in the

hope of seeing a second edition with a supplementary maintains "that the acquirement of the power of visually volume of plates.

In a brief and imperfect notice like the present but scanty justice can be done to a book like the " Pharmacographia," a work which, from the amount of its original matter, the laborious verification of its facts, the accuracy of its references, and the extent of general erudition it reveals, will be received with no grudging welcome, and will be recognised at once and without misgiving as the standard of authority on the subjects of which it treats. HENRY B. BRADY

SULLY'S "SENSATION AND INTUITION"
Sensation and Intuition: Studies in Psychology and
Esthetics. By James Sully, M.A. (Henry S. King
and Co.)

guiding the muscular movements is experiential in the case of the human infant." In support of this somewhat inconsistent position, he gives facts within his own knowledge which we do not feel to be in the least inimical to the doctrine against which they are arrayed. Mr. Sully is more consistent; he thinks it proveable that the eye has no instinctive knowledge of either the distance or the direction of a visual object. He relies greatly on "Recent German Experiments with Sensation" (the subject of his third essay), which, like Dr. Carpenter's facts, appear to us in perfect harmony with the theory they are supposed to disprove. Without doubt, there is no higher scientific authority than Helmholtz, and just for this reason is it specially instructive to observe how readily even he accepts as statements of fact what never could have been more than the suggestions of theory. In the last of his admirable course of lectures on "The Recent Progress of

A YOUNG aspirant to the woolsack had as part of the Theory of Vision," he says: "The young chicken very

his first examination the question, "To whom was the Declaration of Rights presented?" To refresh his memory he cast his eyes on the paper of the gentleman on his left, who had written William I.; willing to give himself every advantage, he next stole a glance at the paper of the gentleman on his right, where he saw William III. "Ah!" thought he, with a knowing twinkle of the eye, "I'll strike the happy medium "—and down went William II. Mr. Sully, in the first of this collection of interesting essays, has struck the happy medium between the evolution and the individual experience psychologies. Mr. Sully has read and pondered all the learning of his subject; but the thoroughgoing evolutionist is not unlikely to accuse him of having done more than "shaded for a moment the intellectual eye from the dazzling light of the new idea." If, as we are told, "it is far from improbable that a fuller investigation of the processes by which our conceptions of space are built up, will render superfluous the supposition of their innateness," it is not at all probable that any other conceptions are inherited. And the evolutionist will not, we fear, be able to draw much comfort from the assurance that "the psychologist, when satisfied of the presence of distinct mental phenomena not traceable to the action of his own laws, will gratefully avail himself of the additional hypothesis supplied to him by the philosopher of evolution;" for it not unfrequently is very difficult indeed to satisfy the psychologist of the presence of anything not traceable to the operation of his own laws. An authority in psychology writing in "Chambers's Encyclopædia," says that the assertions with regard to the instinctive perceptions of distance and direction by the newly hatched chick are, "in the present state of our acquaintance with the laws of mind, wholly incredible." We now know that the chick has not the least respect for those laws of mind; and we have already in these columns (NATURE, vol. vii. p. 300) argued that we have no sufficiently accurate acquaintance with the alleged acquisitions of infancy to justify the doctrine that they are different in kind from the unfolding of the inherited instincts of the chicken. To what we then said Dr. Carpenter has replied on one point in his "Mental Physiology" (p. 179). While admitting that human beings require no education to enable them "to recognise the direction of any luminous object," he

soon pecks at grains of corn, but it pecked while it was still in the shell, and when it hears the hen peck, it pecks again, at first seemingly at random. Then, when it has by chance hit upon a grain, it may, no doubt, learn to notice the field of vision which is at the moment presented to it." In this list of assertions, even the one that might seem most certainly true is a mistake. The chicken does not peck while still in the shell; though that it does so is, we believe, the universal opinion, the actual mode of self-delivery having never been observed. The movement is just the reverse of pecking. Instead of striking for ward and downward (a movement impossible on the part of a bird packed in a shell with its head under its wing), it breaks its way out by vigorously jerking its head upward and backward, while it turns round within the shell. With the advance of knowledge, theories will have, though it may be reluctantly, to accommodate themselves to facts; and after the din of the battle is over, it will be found that the real facts had never had any difference among themselves.

Mr. Sully differs from Mr. Spencer as to the relation of the evolution hypothesis to the question of realism and idealism. He is aware that Mr. Spencer "distinctly affirms that the reality of an independent unknowable force is necessarily involved in his theory of evolutional progress. But this," Mr. Sully observes, "can only mean that every distinct conception of subject and object involves this postulate; and this assumption can hardly fail to strike one as a petitio principii, inasmuch as able thinkers have undertaken to find the deepest significance of this antithesis in purely phenomenal distinctions." Perhaps Mr. Spencer might be able to produce instances in which the facts of the universe have turned out not exactly what able thinkers had undertaken to find them. Considerable strain is put by Mr. Sully on Mr. Mill's formidable definition of matter-that it is "a permanent possibility of sensation;" but we greatly fear that when brought to close quarters the idealist that puts his trust in this verbal monstrosity will find himself left in the lurch. Somehow through "processes of repeated experi ence and sharpened intellectual action, the mind comes," we are told, "to conceive a possible impression as the originating cause of a present one, and so to arrive at that vast stream of objective events which flows on beyond,

and independently of, the actual series of feelings making up its own individual life." To follow this from the idealist's point of view is quite beyond us. A belief in permanent possibilities of sensation that flow on independently of our feelings is in some danger of being mistaken for realism. Mr. Sully, however, is very sure that the realists are wrong; and as a psychologist he must be able, by aid of his science, to explain their error, just as an astronomer accounts for an eclipse. This is how our realistic philosophers go wrong. Under the influence of a refined sentiment of awe, they see what is not there. Not only - does this emotion "lead the mind to anticipate the presence of insoluble mystery where a calmer intellectual vision sees only clear regularity, but it serves to support -conceptions of an unknowable where the closest observation and most accurate reasoning fail to detect any signs of such an existence." The superstitious terror of the rustic transforms a white calf into a ghost; the awe of the philosopher sees a ghost where there is no calf.

In a very suggestive essay Mr. Sully handles the difficult subject of "Belief: its Varieties and its Conditions." He finds "the primitive germ of all belief, the earliest discoverable condition that precedes in its influence that of action, in the transition from a sensation to an idea." In thus attempting to understand how the state of mind called belief resembles, differs from, and is related to other states of consciousness, Mr. Sully is, we think, on the right track. He is, however, by no means free from the crude, popular notion, that belief and volition, considered as facts of consciousness, have some special causal connection with the bodily movements. Indeed, he thinks that Prof, Bain "has succeeded most completely in showing the will to be a secondary and composite state of mind, inferable from more rudimentary states," one of these so-called rudimentary states being spontaneous bodily movements, which occurring by "a coincidence purely accidental" along with states of consciousness, these unlike things get somehow stuck together by "an adhesive growth, through which the feeling can afterwards command the movement." We have repeatedly maintained that while on the one hand there are reasons which seem to compel the belief that on his physical side man is a machine whose movements can never escape by a hair's breadth from the inexorable rule of physical law, there is on the other hand no "better ground for the popular opinion that voluntary movements take their rise in feeling and are guided by intellect, than a superficial observer ignorant of the construction of the steam-engine might have for a belief that the movements of a locomotive take their rise in noise and are guided by smoke."* That Prof. Huxley's bold advocacy of this view at the recent meeting of the British Association has not called out more angry criticism is surely a most hopeful sign of the times.

It is with regret that we must now take leave of this collection of essays, which we have read with pleasure and profit; and we hope that our mode of expressing our criticisms will not be misunderstood or supposed to indicate a want of appreciation. To touch on all the points we had marked for observation would more than double the length of this review. Especially do we regret not being able to say a few words about "The Esthetic * NATURE, vol. ix. p. 179: "The Relation of Body and Mind."

Aspects of Character." If Mr. Sully could admit that conduct cannot be beautiful in so far as it involves struggle, mental effort, for example, in so far as it is moral or virtuous on the subjective side, very little would then stand between him and one commanding DOUGLAS A. SPALDING generalisation.

LETTERS TO THE EDITOR

[The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts. No notice is taken of anonymous communications.]

Sounding and Sensitive Flames *

II.

ANOTHER example of a highly sensitive flame was recently me which seems to show that air-currents described to flowing through gauze at a proper speed are sensitive without the intervention or simultaneous superaddition of a flame. A special kind of Bunsen burner was made with a spiral mixing tube coiled in an inverted cup, at the centre of which is a small chamber covered with wire-gauze at the foot of a short tube or flame-pipe. The gas is admitted by a single jet passing through a cap of wiregauze covering the conical opening of the spiral tube, the object of this cap of gauze being to distribute the air in its approach, and to protect the gas-jet from ignition. The gas-flame burns with a small bright green cone, surmounted by a larger envelope of pale reddish flame, and it is intensely hot. The green cone indicates combustion of the most complete explosive mixture of air and coal-gas, and when the burner is properly adjusted it can only burn on the top of the flame-tube, where it finds the additional required supply of oxygen; but it descends to the wiregauze at the foot of the tube if the air-supply exceeds, or the gas supply falls short of the right proportion. In some of these burners the slightest noise of the kind that commonly affects sensitive flames causes the cone of green flame to retreat into the tube and settle on the wire-gauze at its foot, whence it rises again immediately to the top of the tube, when the sound ceases. The expla nation seems to be that the air-current entering the mixing-tube through the outer gauze cap is in a sensitive condition, and that when thrown into disturbance by the external sounds, it is more quickly seized and is drawn into the mixing tube more rapidly by the gas-jet than when it is flowing over the jet in a tranquil state. The inventor of these burners, Mr. Wallace, assures me that some of them exhibit the most sensitive of sensitive flames, and that he has more than once thought of sending one of them as a most singularly effective illustration of such flames to Prof. Tyndall.

The explanation here given of the sensitiveness of Wallace's Bunsen-flame appears to be in great part correct; but the behaviour of the flame, which by Mr. Wallace's kindness I have seen since the above was written, differs considerably from that described; and some experiments connected with it lead me to modify to some extent the foregoing theory of the origin of sensitiveness in wire-gauze flames, and even, apparently, to except the gauze itself from any considerable share of mechanical action in the process.

The gas

in this burner is first turned low, until the green cone at the centre nearly disappears, and merges into the outer border of the flame from less effective mixture of air with the gas at a low speed of the jet. The flame is now sensitive to the smallest sound, mounting fully one-half higher at every word, or even syllable of a speaker, and at the stroke of a bell, or other acute sound, reaching about twice its ordinary height. It undergoes at the same time no change in its appearance, showing that the contents of the mixing-tube and chamber are merely urged out of the flame-tube with greater speed by some forward impulse of the jet behind. If the sound is continued, as by constantly ringing a bell, the expanded flame gradually subsides, from the expulsion of all the inferior gas-mixture in the burner, reaches its first stature, and passes into a condition of more concentrated combustion corresponding to a fuller, and therefore more rapid admission of gas to the jet; when the sound ceases, the contracted flame gradually recovers its first size and diffuseness from the same cause, namely, the expulsion of all the well-aërated gas

*Continued from p. 6.

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