Imágenes de páginas

My reason for suggesting such an origin for the migration is as it were, whatever it is that constitutes the individuality of the that it takes place every three or four years from ihe same stock. The phenomena presented by parasitic plants seem to plateaux. It is very evident, therefore, that-abiogenesis. bear out this view.

W. H. BeeBy. being now out of couri-some lemunings must be left there to continue the species. Now, it is not likely that the weakest are left behind, otherwise their survival year after year would be

Intelligence in Birds. quite problematical Do not the sacis point unquestionably to A few weeks ago I received a specimen of Podoces panaeri, the strongest being left in continue the race ?

the typical desert bird of Central Asia, which had been kept To the criticism that there is no evidence of fighting having for some months in captivity at Perowsk. The first thing the taken place amongst the migrants, my reply would be that no one, creature began to do, when located by me in a spacious volière, so far as I can learn, has seen a migration stari, or seen one was to pick sume fuod (cooked rice with baked egg:), and to immediately after it has started—the only vime, that is, when bury it in the very thick sand Jayer with which the floor of the effects of such fighting would be apparent, for after a few the cage was provided. This was the incessant occupation of days those seriously injured would have died and have been left the bird on the first day of its instalment. But the task was behind, while those only slightly injured would have recovered almost completely abandoned from the next day ; the bird, evi. sufficiently to be indistinguishable from the remainder.

dently remembering the conditions of its former life in captivity, • Churchfield, Edgbaston.

F. HOWARD COLLINS. found it useless to make provision for the future when a fresh

supply of food daily appeareil. The New Railway from Upminster to Romford, Essex. question are in the habit of making provision in the wild state,

The fact referred to seems to indicate, first, that the birds in On the above railway, now being constructeil, there is a sec- the powersul and slightly curved bill being admirably adapted tion of unusual interest a few yards norih-east of the church at for the purpose of making holes, even in a hard ground. It Hornchurch, showing the Chálky Boulder Clay (15 feet seen) shows, also, how abruptly he habits of animals can be modified under sand and gravel belonging to the highest lerrace of the when the conditions of their environment are changed. Thames Valley, and resting on London Clay. Hitherto, Now, a question naturally arises, How must we regard this Boulder Clay has not been seen in this district in connection habit of burying food—as the result of a long inheritance, or as with Thames Valley deposits, its most southerly exposures lying an effect of constant imitation or older birds by younger ones? ahcut three miles northward, on London Clay or Bagshot Beds.

A. WILKINS. I have been carefully watching this cutting for some time, Tashkend, Central A-ia, November 8, 20. with a view of sending an arcount of it to the Geological Society when it shall have been completely excavated. But, though much has still to be done, the half of it finished has already been sloped, and the arrangement of the beds-clear a month

SIR ANDREW CROMBIE RAMSAY. agn--greatly obscured. It has therefore been suggested to me that a few lines on the subject in NATURE may be the means

HOUGH this illustrious geologist has been laid aside TH

by growing infirmity for the last ten years, the news of enabling geologists interested 10 visit this section while the Boulder Clay is still clearly visible in some portion of the of his death will carry regret into the hearts of many men cutting

of science, not in this country only but all over the world. It may be useful to add that the distance from Hornchurch Born in Glasgow, and intended for a mercantile proStari n is about a mile, and that the visitor, alter leaving the fession there, he spent some few years in business; but, church on his right hand, should take the first road on his left. partly on account of delicate health, betook himself for

T. V. HOLMES. rest and open-air exercise to the island of Arran. One of 28 Croom's Hill, Greenwich Park, S. E.,

| the friends of his early years, Prof. Nichol, of Glasgow December 7.

University, the well-known writer on astronomical sub

jects, had much influence in directing his studies into a Peculiar Eyes.

scientific channel, so that the marvellous geological

lessons to be learnt from the rocks of Arran soon arrested The inability of keeping one eye shut and the other open at the same time, is a fact well known to drill-sergeants. I well Ramsay's attention. Throwing himself with all the ardour Te member, when a conscript some sixteen years ago, how a great

of an enthusiastic nature into the pursuit which he now number of recruits were unable, even after repeated efforts, to do

took up, he was led to climb the mountains and traverse so; but I had no difficulty about it. At that time, 100, my

the glens throughout the lengih and breadth of Arran. eyes were about equal in power ; but at present while the In ihis way, face to face with the facts of Nature, and right eye is of normal power, the left eye presents a much less amid some of the most charming scenery of his native distinct image. I can only ascribe this to the habit of working country, he taught himself the rudiments of geology, and at the microscope with the right eye without closing the left. acquired that clearness of insight for geological structure, It is especially at this work that the defective sight in the latter that love of mountain.forms, and that freshness and originis noticeable. I do not think my len months of rifle practice has ality of interpret slion, which marked him out from his anything to do with it, except, perhaps, in emphasizing the

associates in later years. But above all, by actually tendency to use the right eye, the image of which is now so predominant, that in covering a bull's eye, for in-tance, it is mapping the grouping of the rocks, he gained that pre

cision in field-work which was to bear such notable fruit immaterial whether the left eye be closed or not.


in hi, connection with ihe Geological Survey. He con5 Giesbach Road, L'pper Holloway, December 7.

structed a geological model of Arran on the scale of iwo inches 1o a mile, and made copious notes of the

geological structure of all parts of the island. Grafted Plants.

The meeting of the British Association in Glasgow in REFERRING to Prof. Henslow's paper on "A Theory of the year 1840 proved to be the turning-point in his career. Heredity based on Forces ” (November 26, p. 93), the behaviour The inodel and map of Arran which he had made were of grafted plants seems to require, for its explanation, the piso exhibited at the Geological Section, and he gave a brief session by both stock and graft or something analogous to a account of them and of the geology of the island. Among distinct individuality, call it what we may. It is difficult enough the geologists who listened to him was Murchison, who, to understand, especially in the case of nearly-related forms, why the stock generally ' has no, or so little, influence on the offered to take him on an expedition which the author of

struck with his ability and his devotion to the science, graft; but, assuming the absence of individuality. the difficulty is largely increased. The grast takes its nourishment through the “Silurian System” had then projected to America. the stock, and yet retains its characteristics unimpaired. I argue Ramsay accordingly went up to London, but found that from this that not only does the grast possess an individuality of the voyage across the Atlantic had been abandoned for a its own, but that this is so marked that it can take its nourish journey into Russia, and that he was not to take part in it. ment direct from the stock, while at the same time straining out, Murchison, however, spoke so warmly in favour of his young friend to Sir Henry De la Beche, the Director- the leading part, will ever remain the best monument of General of the Geological Survey, that a post was at once his skill as a field-geologist. His exhaustive memoir on found for him on the staff of the Survey, and before many that region has long since taken its place as one of the days Ramsay was at work at Tenby. He joined the standard works of reference in our geological literature. service in the spring of 1841, immediately after the publi- In his later years he seems to have taken pleasure in cation of the little volume on Arran, which embodied the reverting to some of the inquiries which he started in an fruits of his labours in previous years. From that time early part of his career. He returned with renewed zest onward his life was spent continuously in the work of the to the study of the history of topographical features, disSurvey until he retired at the end of 1881. So capable a coursed as to how Anglesey became an island, and lieutenant did he prove himself to the chief of the staff, traced out the story of the River Dee. In successive that after only four years he was appointed Local editions of the work on the “Physical Geography and Director for Great Britain.

Geology of Great Britain,” which at first was given as From the first Ramsay showed that, with habits of six lectures to an audience of working men, he worked patient observation and cautious induction, he combined out in greater fulness the chief stages through which the a faculty for bold and broad generalization. His remark- surface of this country seemed to him to have passed able paper on the denudation of South Wales, published before it acquired its present features. in 1846, was one of the earliest essays in which the Of the value of his scientific labours full recognition amount and effects of denudation were worked out from was made by his contemporaries. He was elected Predetailed surveys of the geological structure of the ground. sident of the Geological Society in 1862, President of the He then struck the key-note which may be heard through Geological Section of the British Association in 1866 nearly all his subsequent contributions to scientific litera- and again in 1881, and President of the Association itself ture. He was one of the earliest observers to realize that in 1880, when the meeting was held at Swansea. He the existing topography of the land has a long and inter- received the Wollaston Medal of the Geological Society, esting history, much of which may still be deciphered by the Neill Medal of the Royal Society of Edinburgh, and the use of geological investigation.

a Royal Medal from the Royal Society. He was chosen The name of A. C. Ramsay will ever be honourably into the honorary list of many learned Societies at home associated with the story of the gradual working out of and abroad. On the death of Sir Roderick Murchison the records of the Ice Age. Following up the results in 1871, he was appointed Director-General of the Geoobtained by Agassiz, Buckland, Darwin, and others in logical Survey. At the end of 1881 he resigned this this country, he threw himself with all his ardour into office, was knighted for his distinguished services, and the study of the glaciation of Wales, tracing the limits soon thereafter went to reside at Beaumaris, where his of the glaciers of that region, and extending his expe- strength has gradually given way, until he died on the perience by frequent excursions among the Swiss Alps. evening of the 9th inst. His scattered papers in scientific journals undoubtedly There was in Sir Andrew Ramsay such simplicity and did much to stimulate general interest in the history of frankness that men of the most diverse natures were the Glacial Period, and to create a special and volumin- attracted to him, and as they came to know him more ous literature of this subject. His views differed much intimately the gaiety and kind-heartedness of his disfrom those of some of the older geologists of the day, position attached them to him in the closest friendship. and led to some active controversy. Especially did Fond of literature, and glad to relieve the pressure of bis opposition arise when, after studying long and carefully scientific work by excursions into the literary field, he had the erosive action of land-ice, he came to the conclusion acquired a range of knowledge and of taste which gave that certain lake-basins in various parts of the world had a special interest to his conversation. Now and then he been scooped out by ice. Murchison, Lyell, and others found time to write an article for the Saturday Review in of less fame, entered the lists against him ; but he had a which this literary side of his nature would find scope for considerable following among the younger geologists. its exercise. But the daily grind of the official treadmill And this controversy still fitfully continues.

left him all too little time for such diversions. His death In connection with his glacial work, mention should removes from our midst one of the foremost geologists of be made of his bold endeavour to prove that ice-action our day, and from the friends who knew him in his prime, had been in operation more than once in the geological a large-hearted, lovable man, whose memory they will past. His paper on the Permian breccias of England cherish till they too pass away.

A. G. called attention to the evidence of transport of fragments of rock from Wales, and to the resemblance between these fragments and those in glacial moraines and

ON VAN DER WAALS'S ISOTHERMAL boulder-clay. He subsequently detected what he thought to be similar traces of ice-carried materials in the old


. pp. 546 and 627, in favour of a long succession of Glacial periods in the brings clearly to light the importance of the question geological past.

whether the finite size of the particles should be accounted Two of the most suggestive essays he ever wrote were for by an equation of the formhis well-known Presidential Addresses to the Geological

Pilv - b) = }Emu", . .,

(1) Society in 1863 and 1864, in which he worked out, from his wide practical acquaintance with the stratified forma- where Pı represents the internal pressure, equal to the tions of Britain, the idea of breaks in the succession of sum of the external pression p, and the molecul pressure organic remains in the geological record. To the geo- | av, and b some multiple of the total volume by of the logist and the palæontologist these papers marked a

particles ; or if this equation must rather have the formdistinct epoch in the advance of geological inquiry ;

= } Imu( 1+ while to the biologist concerned with the history of

(2) the evolution of organized existence on this planet ihey were full of luminous thought.

Prof. Korteweg's paper and accompanying letter are of date November

4, but owing to an accidental delay they did not reach me until after the By far the largest part of Sir Andrew's contributions to

appearance of my last communication (NATURE, November 26, p. 80). Other geological literature is to be found in the maps, sections, wise I should, of course, have made reference to them. It will be seen that and memoirs of the Geological Survey. The mapping of

Prof. Korteweg draws attention to the form of the virial equation applicable

in one dimension. the volcanic districts of North Wales, in which he took


December 2.

Fig. 1.


In the first case, in substituting p + alv* for Di, and unit of distance only the (1 – 46,/V) th part has to be R(I + at) for Emu?, the well-known formula of Prof. travelled over by the centres of the molecules, the 46z/v th Van der Waals is arrived at. In the second case, the part being economized at the collisions. Therefore the same substitution leads to a quite worthless formula, number of the encounters with the bounding walls is unfit to explaid even qualitatively the conduct of gases augmented in the proportion 1:1 461/V, and the formula under compression.

pv == }£mu is to be changed to The first form is the one which presents itself most

P(v - 46,) = }mu?.

· (4) naturally when, as was done by Van der Waals, the extension of the molecules is considered as a diminution

In 1881, my friend H. A. Lorentz applied the viria) of the volume in which they are moving ; the second is

equation to the calculation of the influence of the size of obtained as a first approximation, when the virial equa

the particles on the pressure. In this manner he obtained tion is extended to the repulsive forces which come into

the formulaplay at the collisions. Of course, both methods, if they

pv = xmu? (1+4)... . (5) could be worked out with absolute rigour, would give the same result; but, this being impossible for both of them, His paper, published in Wiedemann's Annalen, Bd. the question as to which gives the better approximation xii. p. 127, was inserted in the German and English is not at all an unreal one.

versions of Van der Waals's pamphlet “On the Continuity Now, it is extremely improbable that this question of the Liquid and Gaseous States of Matter," at the end should have to be answered in a different way for of the sixth chapter. linear and for three-dimensional space ; yet for linear Considered as a determination of the factor, with space the first method leads to a quite easy and abso- which the total volume b7 of the particles, when introlutely rigorous solution, and the equation thus obtained | duced in v – b, is to be multiplied, our results were idenis analogous to the first form.

tical, and confirmed the opinion expressed by Van der

Waals about the value of this coefficient. Mr. Loreniz V2 V3

viewed his results in no other light, and had no intention at all to substitute his formula (5) for that given by

Van der Waals. Indeed, in the passage of his paper B

which I quote here, he clearly indicates the weak point of his calculation :“Strictly speaking, a correction ought

to be made here, indicated by Mr. Van der Waals ; in In order to prove this, let A B (Fig. 1) represent a linear calculating the number of encounters, the extension? space of length 1, bounded by two rigid walls, A and B, of the molecules should have been taken into account. and let there be moving in this space some perfectly The matter is simplified, however, if the influence of the elastic particles, all of the same mass, m, and length, a, virial arising from the repulsive forces, or the size of the but having different velocities, V1, V2, . Vr. At every molecules, is small; and if a correction to the first order encounter of these particles there will be simply an is sufficient, then the uncorrected value of the number of exchange between their velocities; therefore at every encounters may be used in calculating the small repulsive moment one of the particles will have the velocity vi. virial.” On this particle we fix our attention, following it on its Now it is not impossible to apply to Lorentz's formula way till the next collision. After this collision we leave it the correction alluded to in this passage. In 1875 I calto its fate, directing our attention to the other particle, culated for the first time,” by a more rigorous method, which has now acquired the velocity Vy. Proceeding in the shortening of the mean free path of spherical parthis manner, it is obvious that at every collision a distance ticles, in consequence of their extension in the direction À is economized, which has not to be travelled over by of motion. Some inonths later, Mr. Van der Vaals sucthe centres of the molecules. Starting, then, from the ceeded in the same calculations by a somewhat different wall A and passing over to the wall B and back again, method, extending it to the case of two sets of particles the number of collisions is 2(n 1), and the distance of different diameters. Both calculations lead to the economized 2n1, adding 22 for the collisions against same result, viz. that the mean free path is shortened in the walls). The distance travelled over by the centres the proportion v:v 461 ; therefore the number of the consequently being 2l 2n, it is clear that the number collisions, and the term in the virial equation dependent of collisions with velocity v against one of the walls upon these collisions, must be augmented in the reciprocal amounts to

in one unit of time, and the corre-

proportion ; but then this equation takes the form
2(L - n1)

pu =

mv, sponding change of momentum to

}Emu (1 +


(6) so that the

461 L pressure on the wall is measured by

and becomes identical with the equation (3) of Van der

Waals.3 my?

(3) In this manner the true formula is obtained by means L

of the virial equation, as it has been by the method of Of course, for space of two and three dimensions, the economized distances, and these verifications of the equaproblem is much more complicated. Yet in 1877 I gave tion derived by Van der Waals are not without importa solution of it for spherical particles which, according ance. Indeed, I always held the opinion that it is not to my opinion, is rigorous so far as the several encounters quite allowable to conclude directly from the diminution between the molecules may be looked at as independent of the free path of the molecule to a proportional aug. of one another. For a short time after each collision mentation of the pressure on the bounding walls. The the possibilities of fresh collisions are considerably in number of the mutual encounters of the molecules, fluenced by the proximity of the departing molecule. and the number of their collisions with the walls (or, This influence, certainly of very difficult mathematical rather, their passages through an ideal plane), are not treatment, is disregarded in my calculations.

1 The extension in the direction of the motion is meant here. I have The outcome of these calculations? is that of every translated the first phrase from the original paper in Wied. Ann., where it " Verslagen en Mededeelingen der Kon. Ak. 11. Amsterdam, 2° Reeks,

runs: "Streng genommen müsste man also hier eine Correction anbringen, Deel 2 ; Archives Neerlandaises, t. xii.

wie sie von Herrn van der Waals angegeben würde ; man hätte nämlich bei

der Stosszahl die Grösse der Molecule zu berücksichtigen." I am bound to acknowledge that the same correction, which is indicated further on for Lorentz's calculations, has to be applied to the number of

? Verslagen en Mededeelingen, 2 Reeks, Deel x.; Archives Veerlandaises, collisions given in my paper.


48,) =

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3 I owe this remark to a verbal communication by Van der Waals.

t. xii.

proportional numbers under all circumstances. A change THE OCTOBER ERUPTION NORTH-WEST OF in the shape of the molecules, or an augmentation of

PANTELLERIA. their diameters, will affect the first number in a much greater proportion than the second. But, as I have SOME time after the news arrived in this

country of shown, the equation of Van der Waals holds good, inde- the volcanic outburst in the neighbourhood of Panpendently of this assumption.

telleria, my friend Mr. Gerard Butler, F.G.S., undertook

D. T. KORTEWEG. to visit the island, and to investigate the interesting Amsterdam, November 4.

phenomena that were being exhibited there. Mr. Butler has now returned, having made a large collection of specimens of rocks and minerals, and I trust that before

long we shall have fuller information concerning this THE BIRD-GALLERY IN THE BRITISH

remarkable district. The following short note embodies MUSEUM

the general results of his inquiries concerning the recent

eruptions ; but telegrams received since his return state A LONG: NEEDEDO and much-wished for reform, that renewed outbursts have led to the formation of an

island at the spot, and mariners have been warned to specially invited, has been commenced in the Bird- avoid it.

JOHN W. JUDD. gallery of the British Museum. Under the old régime Royal College of Science, London, December 14. at Bloomsbury, the rule was, as it is even now in most of the Continental Museums, that every specimen should be

In NATURE of December 3 (p. 120), a short sketch is stuffed, and exhibited in the public gallery. The natural, given of a paper by M. Ricco on the above, which those if not the necessary, consequence of such a rule is that, interested in the subject may read in the Comptes rendus as time progresses, the shelves become crowded with

for November 25. badly mounted specimens, which are very unpleasing to

It may be worth while for one who visited Pantelleria the general observer, and most inconvenient to the be no foundation for the idea conveyed by many Eng;

soon after the eruption to point out that there appears to scientific worker. In the British Museum, however, the idea of mounting island,” in NATURE (loc. cit.), that an island comparable

lish accounts and by the words island," "erupted every specimen has been long ago abandoned.

The main collection for scientific work is, we need hardly

to Graham's Island was formed. say, that of skins. These are arranged in cabinets, in

It seems that by a submarine eruption which, after numbers which it would be impossible to find space for if prefatory earthquakes between October 14 and 17, was “mounted.” When thus disposed of they are much more

first observed on the latter day, about 5 kilometres to the easy to find, and more convenient for examination, than north-west of Pantelleria, a narrow band of Aloating “mounted”

specimens Though it may be sometimes bombs, extending for about a kilometre in a north-east necessary to refer to the Bird-gallery, the working orni- and south-west direction, was produced. thologist of this country, as a rule, uses only the skin

The persistence during the eruption of this linear band collection.

may perhaps indicate the line of fracture of the sea

bottom. This being so, the question arises as to what is the best way of making the Bird-gallery useful, and attractive to

There appears to have been always deep water at the the general public. As to this there can be no question, middle and ends of the floating shoal of bombs found no

scene of eruption. Ricco tells us that soundings at the it appears, that the Bird-gallery should be fitted up as an " Index Museum," and should contain series of the

bottom at 320 metres. principal types of bird-life arranged in systematic order

The brittle cindery bombs readily broke up, giving vent from the highest to the lowest. Every family should be to the superheated steam they contained ; when, or upon placed in a separate case, in its proper position between

their becoming otherwise waterlogged, they sank, so that, the two groups to which it is most nearly allied. In

on October 26, soon after the eruptive action ceased, all each family a series of well-mounted specimens should

traces of it had disappeared in deep water. illustrate the principal sub-families and genera, and the

G. W. BUTLER. male and female and other plumage of the leading species. Nests and eggs should be added to show the mode of

NOTES nidification, and maps to show the areas of distribution. Diagrams and preparations of particular structures

WE regret to have to record the death of Prof. Stas, the should be placed at the head of each group, to exhibit eminent Belgian chemist. He died at the age of seventy-eight. its special peculiarities; and finally, every specimen and diagram should be clearly labelled and explained. It will dent read from the chair a letter from Prof. Dewar, which had

At last Thursday's meeting of the Royal Society, the Presireadily be understood that a Bird-gallery filled up in this way would be a most instructive object, and much more been put into his hand as he entered the meeting-room, in useful and attractive than the crowded rows of uniformly which Prof. Dewar stated that he had at 3 p.m. that afternoon set-up specimens that are offered to view in most public placed a quantity of liquid oxygen in the state of rapid Museums. Some such plan as this, we take it, is what ebullition in air (and therefore at a temperature of – 181° C.) the authorities of the British Museum have now in between the poles of the historic Faraday magnet in a cupview.

shaped piece of rock salt (which is not moistened by liquid For a commencement, the family of Woodpeckers has oxygen and therefore keeps it in the spheroidal state),” and to been selected, and a case devoted to its illustration has his surprise, Prof. Dewar saw the liquid oxygen, as soon as the been fitted up. A series of well-mounted specimens magnet was stimulated, “suddenly leap up to the poles and shows the leading forms of the group, and diagrams, remain there permanently attracteil until it evaporated.” preparations, and maps exhibit its principal peculiarities and the distribution of the species.

ACCORDING to information sent to Berlin, Emin Pasha and This is at present only the beginning of a very Dr. Stuhlmann, travelling in the region between Lakes Victoria, important change of plan. But there can be no question Tanganyika, and Albert Edward, have discovered what they take that if the scheme is carried out, and the whole Bird

to be the ultimate source of the Nile. This is a river called gallery is treated in a similar way, an admirable reform will have been effected.

Kifu, which is supposed to have its sources in the Uhha country,

lying to the east of the northern part of Lake Tanganyika,

about 4° of south latitude. It Aows into the southern end of the organizing bodies. Among those present were Sir George Lake Albert Edward.

Stokes, Prof Bryce, Prof. Jebb, Mr. James Stuart, the President

of Magdalen College, Oxford, the Master of University College, The death of Dr. F. C. Dietrich, Keeper of the Botanical

Oxford, and the Master of Selwyn College, Cambridge. Lord Museum at Berlin, is announced. He was eighty-six years of

Cranbrook reminded the deputation that his official duties age.

related only to public elementary schools, and that a Govern. At the annual general meeting of the Institution of Electrical ment grant could be obtained for the University Extension Engineers on Thursday, December 10, Prof. Ayrton was elected movement only from the Trea-ury. He expressed sympathy, President for the coming year.

The following are the Vice however, with the objects of the movement, and promised to Presidents : Alexander Siemens, R. E. Crompton, Sir David consider carefully and to bring before his colleagues the arguSalomons, and Sir Henry Mance. In moving the adoption of the ments advanced by the deputation. Referring to the general annual report, Prof. Crookes said that the number of members question of secondary education, Lord Cranbrook said it was elected during the past year was greater than in almost any most desirable that clever boys and girls who have passed previous year. He announced that Prof. Nikola Tesla is on his through the elementary course should be enabled, by bursaries way to England, and had promised to lecture before the Insti- or in some other way, to go to intermediate schools, and thus be tution in January next. Prof. Crookes added that the Council prepared for such instruction as is offered by University Extenwould spare no pains to insure that the lecture should be sion lecturers. He seared, however, that those who expected thoroughly well experimentally illustrated. Mr. W. H. Preece, this object to be attained by means of a Government grant F.R.S. (Past- President), read a paper on “ The Specification of might have to wait for some time." Insulated Conductors for Electric Lighting and other Purposes." In this paper the fallacy of the present mode of specifying of Great Britain, Mr. Leon Warnerke lately undertook to sub

On the invitation of the Council of the Photographic Society electric light conductors was exposed, and a new standard of mit to the Society a description of the photographic technical insulation, based on the well-known qualities of gutta-percha,

schools on the Continent. With that ohject in view he visited, was proposed. The qualities of the numerous insulating materials now in the market were measured and determined in this during last summer, Belgium, Germany, Austria, and Russia,

The results are embodied Dew standard, and it was shown that any classification of cables taking notes with pencil and camera. should be based on the pressures to be resisted, and should

in an interesting paper which was read at a recent meeting of

the Society, and is now printed in the Photographic Journal. depend on the thickness of the insulating wall. The introduc. tion of cheap and nasty cables, owing to competition and the

The organizing joint committee of the Essex County absence of specification and inspection, was strongly commented Council and the Essex Field Club on technical instruction on. It was shown that all danger was eliminated by the use of have issued a circular announcing that they have resolved proper material and proper design. The paper concluded with

to appoint a certain number of lecturers ou science subthe recital of Mr. Preece's latest specification.

jects. The services of these teachers are offered free (with PROF. A. Hansen, of Darmstadt, has been appointed to the

the exception of travelling and hotel expenses of the lecProfessorship of Botany and Directorship of the Botanic Garden

turers, where necessary) to local technical instruction comat Giessen.

mittees, under certain conditions to be settled hereaster; the

local committees guaranteeing audiences or classes of students Prof. E. WARNING, of Copenhagen, is at present engaged (not less than twenty in number), providing rooms, gas, &c., on a botanical expedition to the West Indies and Venezuela. and defraying all necessary local expenses. Syllabuses of short Herr G. Schweinfurth and Prof. O. Penzig have returned from courses of lectures already approved are sent with the circular. their journey in Abyssinia ; and Herren J. Bornmüller and They relate to elementary vegetable physiology, economic Sintenis from their botanical expedition, in the course of which entomology, and elementary practical mechanics. they have visited the island of Thasos, Mount Athos, and the Thessalian Olympus.

The Royal Commission for the Chicago Exhibition are

anxious to comply with a request made to them by the execuo The following are the lecture arrangements of the Royal tive authorities of the Exhibition, that a typical collection of Institution before Easter, so far as they relate to science :-Prof. economic British minerals may be included in the British John G. McKendrick, six Christmas lectures 10 juveniles, on Section, and they are now applying to owners and managers lise in motion, or the animal machine ; Prof. Victor Horsley, of mines, asking for specimens of the principal British minerals. twelve lectures on the structure and functions of the nervous Mr. B. H. Brough, the Instructor in Mine-surveying at the system (the brain); Prof. E. Ray Lankester, three lectures on Royal College of Science, South Kensington, has kindly undersome recent biological discoveries ; Dr. B. Arthur Whitelegge, taken to classify and arrange the collection, and any suitable three lectures on epidemic waves ; Prof. J. A. Fleming, three specimens may be addressed to him. What is required is lectures on the induction coil and transformer ; the Right Hon. not specimens of special value or rarity, but samples of ordinary Lord Rayleigh, six lectures on matter, at rest and in motion. ores, &c., so that the collection when complete may be The Friday evening meetings will begin on January 22, when a fully illustrative of the inineral resources of the kingdom. At discourse will be given by the Right Hon. Lord Rayleigh, on the close of the Exhibition the collection will be presented to the composition of water ; succeeding discourses will probably be an American Museum given, among others, by Sir George Douglas, Prof. Roberts. Austen, Mr. G. J. Symons, Prof. Percy F. Frankland, Sir

PROF. H. A. Hazen, acting under instructions from ihe David Salomons, Prof. L. C. Miall, Prof. Oliver Lodge, Mr.

U.S. Weather Bureau, is in Chicago preparing a report on its John Evans, and Prof. W. E. Ayrton.

weather-the mean temperature, the winds, snows, showers,

humidity, early frosts and late : nows. The report will be based Last week a deputation of gentlemen interested in the Uni- on all the observations and records made for the last fifty years versity Extension movement had an interview with Lord Cran: the object being to convince everyone interested in the apbrook, President of the Privy Council, to ask for a Government proaching Exposition that Chicago is exceptionally favoured in grant in aid of the local lectures delivered under the auspices of point of fine weather.

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