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It follows that the incidence of rays possessing the property LETTERS TO THE EDITOR

suggested above will tend to increase the temperature of a gas. [The Editor does not hold himself responsible for opinions ex. The discharge which takes place at an encounter will, how.

pressed by his correspondents. Neither can he undertake ever, be an oscillatory one, and will lead, therefore, to further to return, or to correspond with the writers of, rejected generation of undulatory rays. manuscripts intended for this or any other part of NATURE. Considering two masses of gas at unequal temperature, the No notice is taken of anonymous communications. ]

impacts in the hotter gas, being the more frequent and violent,

will give rise to the more copious emission of rays, and these Misleading Applications of Familiar Scientific Terms. falling on the cooler gas, will produce the greater electric disMAY I, not as an expert in science, but as one who has made in collisions between the molecules.' The feebler rays from the

sociation resulting in the greater acquisition of kinetic energy some research into the conditions of lucidity, venture to thank

colder gas will have less effect on the molecules of the hotter you for the protest which appears in your current number

one, and the kinetic energy supplied in this way will not against a misleading application of the familiar term Light”?

compensate for that lost by radiation. Thus the is This is not of course the only instance of the kind; but it seems

theory of

exchanges will hold good. especially regrettable as tending, by the very success and popularity of the Lectures reviewed, to introduce gratuitous confusion

A still more important consequence of such a theory is that

no interaction will take place between the ether and molecules into youthful minds. I may perhaps be pardoned for adding that I was fortunate except where there are encounters between the latter, and,

moreover, the interactions which occur in an isolated mass of enough in my little book, "Grains of Sense,” published last year, to anticipate the verdict of your reviewer, and to point gas will not affect the translational velocity of its centre of mass,

nor the angular momenta about axes through its centre of mass. out how much, in this and similar cases, such modes of ex

Thus it results that the celestial bodies go on in their course pression on the part of scientific men tend on the one hand to diminish our precious and too slender store of clearness of experiencing no resistance whatever from the ether. thought, and on the other to hinder the progress of science absorbed before it reaches the earth, no longer implies the com

On the other hand, the fact that light from distant stars is not itself.

V. WELBY.

plete absence of matter in interstellar space. Isolated molecules April 1.

will absorb no energy from the ether; and so long as the mole

cules moving about in interstellar space are assumed to be so The Kinetic Theory and Radiant Energy.

few and far between that collisions practically never occur,

there will be nothing to impede the passage of light or heat In the course of the discussion which took place in your rays. It is only when such rays fall on assemblages of molecolumns during the winter of 1894-5. on the kinetic theory of cules sufficiently dense to possess the attributes of what we call gases, emphasis was rightly laid on the difficulty of reconciling matter-as, for example, when they reach our atmospherethe law of partition of energy among the different degrees that absorptior. of energy will take place. of freedom of molecules of gases with the large number of The phenomena of irreversibility and of degradation of such degrees of freedom indicated by their spectra, and, energy would thus, so far as the present view goes, be regenerally, of explaining, on the kinetic theory, ihe relations stricted to material bodies, and hence the conditions necessary between matter and the ether required to account for for the existence of life on our earth may have been brought radiation. It was even suggested, by one writer, that the ether, about without the enormous waste of energy which would be with its vastly larger number of degrees cf freedom, must required in the absence of some such theory. ultimately absorb all the energy of the molecules. I instanced A photo-voltaic theory of photographic action formed the the case of a sphere moving in an infinite mass of perfect liquid subject of exhaustive experimental investigation at the hands as exemplifying a system where no such ultimate absorption of of Herr Luggin last year, and photo-voltaic theories of vision energy would take place, and pointed out that everything de- have also been proposed. It would thus seem that the analogy pended on the laws according to which transference of energy between the action of heat rays, visible-light_rays, ultra-violet took place between the molecules and the ether.

rays and Röntgen rays may be complete. The question still The object of this letter is to show that the subsequent remains, how are ethereal waves able to affect the electric state discovery of the Röntgen rays has suggested a theory of the of assemblages of molecules ? But since Röntgen-ray physicists radiation of heat which may possibly throw considerable light have proved that they do this, the question has to be faced on the difficulties referred to by affording an answer to the in any case. It is now rendered no more difficult, and, on question, " If the temperature of a gas is proportional to the the other hand, our theories of the relations between ether and mean translational kinetic energy of the molecules, how comes matter are simplified by referring radiation of heat to the same it that this kinetic energy can be transferred from one set of phenomenon.

G. H. BRYAS. molecules to another by radiation through the ether?"

Consider the Röntgen rays : we know, firstly, that they are produced by the impact of the kathodic rays on the Crookes?

Note on Mr. Wood's Method of Illustrating Planetary tube, these latter consisting not improbably of streams of

Orbits. bombarding molecules ; secondly, that they not only have the I FEAR that Mr. Wood's beautiful method of illustrating power of discharging electrified bodies, but also of modifying planetary orbits by means of a bicycle ball rolling on a glass the electrical state of gases in such a way as to enable these to plate about the pole of an electro-magnet (NATURE, April 29, discharge bodies. In this modified air, to which Villari has 1897), has rather fallen into disrepute in the minds of many applied the somewhat barbarous name of “aria Xata" or physicists since its criticism by Mr. Anderson in NATURE, May "xd. air," some kind of dissociation of the electrons must

13, 1897. Mr. Anderson there states that the law of attraction necessarily have taken place.

in such a case would be that of the inverse fifth power of the Arguing from analogy the idea suggests itself that the distance. This could only be true if the ball were of very soft encounters between molecules of a gas, no less than the kathodic iron. A bicycle ball is far from this, and becomes strongly mag. bombardments, may give rise to radiations, and these, too, netised after brief use in the experiment, behaving like a perwhen falling on another mass of gas may modify the electrical manent magnet of great coercive force. Under these conditions state of its molecules in such a way that their original electrical the attraction between the pole and the ball will vary approxistate is only restored by encounters between them.

mately as the inverse third power. There is also another factor Now taking, as a simple illustration, two oppositely electrified to be considered. If the true pole lies below the glass plate, perfectly elastic conducting spheres ; as these approach one only a certain component of the total force is active in producing another, they acquire kinetic energy in virtue of their attraction. the attraction towards the centre of motion. To determine what On coming into contact they are discharged and the attraction the law of variation of this component will be, I have had one of ceases, so that their kinetic energy of separation is greater my students take a number of series of observations on the than that which they had previously to coming within each attraction of a bicycle ball along a plane perpendicular to the other's influence. Again, when a charged and an uncharged axis of a magnet. body impinge, the charge is distributed between them ; they In the experiments the magnet was horizontal, and the bicycle repel one another as they separate, and again acquire an increase ball with its magnetic axis vertical was fastened to one end of a of kinetic energy-as in the ordinargy pith-ball experiment. strip of spring brass, the other end of which was clamped fast in

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a sliding clamp so as to be raised and lowered. The bending of the brass strip under the attraction of the magnet on the ball

Description. was measured by means of a telescope and scale, the mirror being fastened to the end of the strip. As the motion of the ball was entirely in a plane perpendicular to the axis of the Unvaccinated magnet, the law of variation of force must have been very nearly. These contain 21 cases, jo the same as in the orbit experiments.

deaths, whose description in.
When the ball was directly over the true pole, which lay about cludes the word vaccination
1 cm. from the end of the conical pole.piece, the law was nearly or vaccinated
that of the inverse cube, the observations being taken between “Vaccinated in infancy,” no de-
the limits of 3 cm. and 14 cm. from the axis of the magnet. scription of vacc. marks
Other series were taken with the plane of motion of the ball at Do. "no marks," very abundant
different distances from the pole, and it was found that with the small-pox eruption
plane of motion at 2-8 cm. from the true pole the law of the Do. "one" vacc. mark
inverse square was very closely obeyed between 4 cm. and 14 cm. Do. two do.
from the axis. These limits cover the region in which the orbits Do. three do.
would in most cases be formed. The exact law of force as Do 4, 5, 6, 7 and 8 vacc.
determined by least squares from seven observations between marks
the above limits was that of the 2'1 power of the distance.

Do. (?) v, marks, very abundant
Louis W. AUSTIN.

eruption The University of Wisconsin, Madison, Wis., March 16.

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219 An Extraordinary Heron's Nest. I SEND you a photograph of probably the most extraordinary The accepted fatality before Jenner's birth was 16 6 heron's nest ever discovered in this or any other country. During There were

Cases. Deaths. a gale it was blown from the top of an elm tree in the heronry Re-vaccinated cases at Gloucester 173 9 5'2 on Stoke Hall estate in Norts, the seat of Sir Henry Bromley, Bart. It is of unusual size, and almost exclusively composed of

These had all kinds of v. marks up to 8 in number, and some wire of varying lengths and thickness; the centre, or “cup,”

had been repeatedly re-vaccinated ; one “ often” re-vaccinated. alone being composed of fine twigs, grasses and feathers.

If the same energy had been put into a critical proof of the Several other nests of the heronry, which had also been blown

vaccination of each one as was into avoiding condemning down, contained pieces of wire cleverly worked in with twigs in

vaccination, there would be little to show, even in fatality, in the the usual way, but this was the only one entirely composed of

above for vaccination ; as it is, it kills every vaccine dogma. that material, as far as the main structure is concerned. There

Alex. WHEELER. are happily now a very flourishing heronry at Dallam Tower, Westmorland, the seat of Sir Henry Bromley's son, Mr. Maurice MR. WHEELER, it must be assumed, is wishful to prove that

the fatality amongst the vaccinated is as high, or at any rate is not lower than amongst the non-vaccinated. It is surely not necessary for him to separate vaccinated cases into those with marks” and those with “no marks,” since to him it should be immaterial whether a patient be vaccinated or not.

Taking Mr. Wheeler's own classification, we find that of the unvaccinated cases, 679 in number, 287 died, giving a percentage mortality of 42'2; whilst of the vaccinated cases, 1300 in number, only 147, or 11'3 per cent., died. These figures should surely be enough to settle the question as regards percentage mortality, and the mere inclusion of the 21 cases and 10 deaths, whose description includes the word “vaccination or “vaccinated,” does not in any way invalidate the general conclusions to be drawn from these figures.

If now, however, a class for the “under-vaccinated” be included, the second class may be divided into “under-vaccin. ated ” 89 cases with 27 deaths, or 30'3 per cent., and vaccinated 1211 with 120 deaths, giving a mortality of only 9.9 per cent. It is evident that Mr. Wheeler's table in no way conflicts

with the figures given in the Report (except in one small partiBromley-Wilson, and although I have been familiar with it " off “under-vaccination” as used by Dr. Coupland, who used the

cular, noted below), but is based on a misconception of the term and on " for very many years, and with several other heronries

term to signify those cases of small-pox which had undergone in various parts of the country, I never knew of the birds using wire in the construction of their nests. I have several records of incubation : i.e. fourteen days before the appearance of the

vaccination at any time within the (generally accepted) period of rooks using wire in large quantities in the construction of rash. In the list of “unvaccinated” cases are included a few their nests. Particulars of one very remarkable instance were which were actually vaccinated in the invasion period. No published in the Yorkshire Weekly Post of May 19, 1894, and of doubt some of these should be placed in the vaccinated class ; another in the same paper for June 23, 1894. Both of these but others, again, should be grouped in the unvaccinated class. freaks took place in India : one at Calcutta, the other at Ran. The Royal Commission reckoned the whole group, instead goon. The other curious feature of the Stoke Hall phenomenon of a large proportion, in this latter class, which is perhaps not is that there is, and never has been, any lack of ordinary building strictly scientific and accurate, Mr. Wheeler, however, goes material, and that all the wire used must have been carried a far further astray in including them all in the vaccinated class, great distance.

G. W. MURDOCH. which is clearly erroneous. It may be pointed out in this conWestmorland.

nection that, in his recently published work, Dr. Cory gives

some most interesting facts which tend to show that vaccina! “ The Story of Gloucester."

immunity is not obtained until nine days have elapsed after

inoculation. It would be easy, therefore, from the table on REFERRING to your article (p. 221), I think you cannot have page 149 of the Report, to divide the total 89, there reckoned looked at pages 70 to 117 of the Gloucester Small-pox Epide as "under vaccination," into two sections : (a) those vaccinated Blue Book, by Dr. Coupland. I have analysed all these cases, before, and (6) those vaccinated within eight days, of manifesting and here is the result.

small-pox. If this were done, there would be added (a) to the * vaccinated" class 10 cases with 3 deaths; and (b) to the unvaccinated 255; this, too, in families of the same class, in the “unvaccinated” class 79 cases with 24 deaths.

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same streets, and living under similar sanitary (or unsanitary Without checking Mr. Wheeler's figures by laboriously going surrou ngs as those in which every child was unvaccinated. through pages 70-117 of the Report, it is simply necessary to May we not legitimately infer that had all the Gloucester deduct those " under-vaccinated” from his several lists. His children at these ages been vaccinated, only 1/7th of those classes of “no marks” and “? marks" correspond with Dr. that did suffer would have suffered, and the mortality would Coupland's groups of “alleged” and “doubtful” vaccination, I have been less than 1/60th of that to which it did attain ? except that Dr. Coupland's figures give one case less and one Vaccinators are said to be incapable of viewing this subject death more than Mr. Wheeler's. Although it is highly prob- impartially, but Dr. Coupland is most judicious in the handling able that many of these uncertain and doubtful cases were really of his figures, and it is apparent that the evidence that he has unvaccinated, the Report includes them, as does Mr. Wheeler, collected from careful observation weighs with him as much or in the “ vaccinated" class (see page 153, &c.).

more than do the figures he has brought together ; and it is certain

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* Discrepancy due to inclusion by Mr. Wheeler of one death too many among “vaccinated in infancy,” and one case too many among the ? vaccinated.”

It is difficult to grasp Mr. Wheeler's point in presenting the that if those who deny the efficacy of vaccination could have the figures in this way. it might be useful if these questionable experience that he has had, they would cease to hold the view cases had all been turned over to the “unvaccinated" class; but that he is prejudiced. Any one who considers his Report why does he detach them from the rest of the admittedly judicially must confess that he has presented the facts extremely vaccinated ? He could not have intended to show, as his own fairly and impartially, and that he evinces far less bias than those figures do, that post-vaccinal fatality diminishes with a rise in who, on very slight and shadowy information, are undoubtedly the presumed greater efficiency of vaccination as evidenced by unreasonably opposed to vaccination—the very people, in most the number of scars. Dr. Coupland does not enter into the cases, who bring the charge of partiality. Every one knows that question of marks. It has been done over and over again, and where large numbers of statistics have to be collected, errors in both his Dewsbury and Leicester Reports Dr. Coupland of fact may creep into records, and that, with fuller knowledge, makes a most valuable contribution to this question. The main slight modifications may have from time to time to be made. As object of the inquiry at Gloucester was to determine the broad regards the main facts of Dr. Coupland's records, however, the question of the occurrence and fatality of small-pox in the most exacting will find it difficult to trace any important in. vaccinated and unvaccinated.

accuracy. In respect to the records concerning children the Perhaps the most important point that the Gloucester epidemic facts are indisputable, and lead to the mournful conclusion illustrated is one that is passed over by Mr. Wheeler, and that amongst these there would have been vastly less suffering one which unfortunately appears as though the opponents and far fewer deaths in the Gloucester epidemic, had not infant of vaccination in their pursuit of a fad had become callous vaccination been so widely neglected. to the fate, in this instance, of the Gloucester children, but As regards re-vaccination it is difficult to see how Mr. Wheeler also of the children wherever there is an outbreak of small- obtains the figure 173. In the table (p. 46) there are given 190 who pox.

were stated to have been re-vaccinated. Assuming that each of About the effects of the vaccination or non-vaccination of these was really and efficiently re-vaccinated a large assumption children there can be no dispute. In this connection it is only—the fatality would be 47, or much below the general vaccinnecessary to refer to the figures of those attacked between one ation rate. There are, however, several difficulties to be surand ten years of age, and especially at the incidence rates given mounted before a satisfactory demonstration of the relationship of near the end of the Report. Indeed, if only those households re-vaccination to small.pox can be arrived at ; and one of these are taken in which some vaccinated children are to be found, it ap- especially, that of the true interpretation of a failure to take," pears that the incidence of small-pox among the vaccinated children is a most important one. This failure "to take” does not was only 10 to 100, though amongst their unvaccinated brothers necessarily imply that the subject is immune. Then there is also and sisters it was 10 to 14; whilst the death rate (per 1000 of those the fallacy of recent re-vaccination which, like recent primary exposed to infection) was for the vaccinated less than 4, for the vaccination, may have been done too close to the date of the

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onset of small.pox to have any influence on the disease (see Douglas has stated that, with the removal of the refollowing table) ?

sidences and of the secretarial offices to Whitehall, the Small-pox in the Re-vaccinated.

Government find that they will have at their disposal

a much larger space than had been previously contem190 persons who were stated to have been re-vaccinated were

plated, and that therefore they will be able to put the attacked by small-pox. Of these : (a) 52 were

Science and Art collections on the one side of Exhibition “ re-vaccinated at various periods prior to epidemic, in some cases several years.

Road. Do you think the space thus provided will be

sufficient for the whole of the collections being placed In 37 this re-vaccination was stated to have been successful, together? The witness : I do not think so, and that was

and 2 of these patients died. In 15 this re vaccination did “ not take".

my reason for saying that I saw no ground for changing '- I died.

the opinion I have already expressed on the subject. I (6) 30 were “re vaccinated” between 3 months and 14 days of contemplate that the museums will increase, and I do the attack of small-pox.

not think it would be wise to consolidate the collections In 8 the vaccination “took.”

on one side of the road. In answer to further questions, In 22 “ did not take."

Sir John Donnelly said he thought it was most desirable (c) 108 were re-vaccinated” within 14 days of appearance of that the Geological Museum in Jermyn Street should be small-pox eruption, some of them even in early days of attack. transferred to South Kensington. The library which In 83 vaccine vesicles appeared-4 died.

was now in Jermyn Street would be of great value at In 25 the vaccination did not take ”-- 1 died.

South Kensington, and under the present system of

division they had to duplicate many of the books. He Where k'e-vaccination believed to have been successful. would undertake to bring this view before the Lord (a) 37 cases-2 deaths-fatality 54 per cent.

President and the Vice-President of the Council. As to (6) 8 nil.

the Art side, the theory that it was better to have a large (c) 83 4 4.8 per cent.

series of small rooms in which they could classify their

objects rather than a series of very large halls or rooms Where Re-vaccination known to have been unsuccessful. was absolutely impracticable in their case. He was dis(a) 15 cases—2 deaths---fatality 13-3 per cent.

tinctly in favour of residences being provided for some (6) 22 nil.

of the officers--say four-either in the same buildings (C) 25

4'0 per cent.

in which the collections were housed or very close to Or of whole number, 4:8 per cent. ; or if we take whole

them. There was, he knew, a morbid fear of fire being number (190), irrespective of date or of success, a fatality of 4.7

caused when the residences were in the actual building,

but he did not himself believe that this was a very great Mr. Wheeler's statement that the accepted fatality before source of danger. Jenner's birth was 16.6 has very little bearing on the question, since the epidemic at Gloucester gave 219, and this, including the 42'2 per cent, unvaccinated fatality at all ages, which is less

PHOTOGRAPHY AND TRAVEL.I than that between 1 and 10 years, the period of most fatal smallpox, in the pre-vaccination days. The Gloucester outbreak was THE

HE globe-trotter of to-day is almost as notorious undoubtedly unusually virulent ; but, surely, equally severe for his poor photographs as his ancestor of the epidemics are on record.

Mandeville era was for his traveller's tales. Without THE WRITER OF THE ARTICLE. instruction in the technical part of his work, and without

the geographical training required to teach him what to

look for and how to view it, he habitually brings home THE SOUTH KENSINGTON SCIENCE productions which may be of interest as studies for an BUILDINGS.

impressionist artist, but are of little or no value to the

student of nature. Hence it is with particular pleasure WE TE are glad to see that the various important matters

that we welcome the republication in a generally accesconnected with the extraordinary proposal to spend

sible form of a selection of Mr. Thomson's magnificent some eight hundred thousand pounds in interlacing the Science with the Art .buildings-chemical laboratories

photographs made in China. These were taken before with picture galleries-are being considered by a Parlia

the days of dry plates and snap-shots, when it was. mentary Committee. This is more especially desirable,

necessary to prepare and develop the plates on the spot,

and to employ a camera of large dimensions not easy since, as we have previously pointed out, it is stated that

to transport through regions where, to says the least, about half the money proposed to be spent is sufficient for present needs.

strangers are not received with overwhelming hospi

tality. The Times gives the following account of the meeting of the Select Committee on Friday last, Sir F. S. Powell

The photographs are selected so as to give a con

nected idea of life in China proper in all its aspects, and presiding. Sir John Donnelly, secretary to the depart

also to illustrate the natural scenery of many of the proment, was further examined. Sir H. Howorth said it would be of great assistance to the Committee if they

vinces and of Formosa. The pictures are so satisfactory could get from the officials of the department an ex

from every point of view, that it is no slight to say that pression of their views as to the changes which were

the letterpress takes a humbler place when one estimates.

the value of the book. The text for the most part is. desirable or were not desirable in regard to the housing of the Science and Art collections. The witness said

descriptive of travel, and illustrative of the photographs,

incidents and anecdotes being introduced for that purthat was rather an awkward question ; he really did not think it would be proper for him to volunteer any state

pose. It would have been more useful if the exact order ment which might conflict with the present proposals of of the journeys and their date had been mentioned ; and the Treasury and the Board of Works. He had already situation of the regions visited.

a map might very well have been added to show the stated that, in his opinion, the Science collections should be on the west side of Exhibition Road and

Three introductory chapters deal with the condition of the Art collections on the east side. He believed that

China now and in the past, and with the Chinaman that was the proper solution of the South Kensington

abroad and at home. Having regard to the somewhat question, and he had seen no reason in what had

acute interest now being taken in China by the nations aken place since he gave expression to that view to 1 "Through China with a Camera." By John Thomson, F.R.G.S.

With nearly 100 illustrations. Pp. xiv + 284. Small 4to. (Westminster : change his opinion. Sir H. Howorth: Mr. Akers

A. Constable and Co., 1898.)

of Europe, the perusal of these chapters should prove comparatively few astronomical observers, that means of useful ; and so should the description of the various great communication were slow, and that the importance of centres of population on the coast, in the Yangtze valley recording these objects as precisely as possible had not and Pekin.

been recognised. Not the least interesting of the photographs is that The present is perhaps an appropriate period to refer to which, by the courtesy of the publishers, we are able to this subject, for it was in 1798, just a century ago, that give here. The illustration shows two ancient astro- the first systematic attempt was made (by Brandes at nomical instruments of purely Chinese construction, Leipzic, and Benzenberg ai Dusseldorf) to determine the which stand on the walls of Pekin, with instruments heights of meteors. Schröter had in 1795 seen a shooting. dating from the thirteenth century, and others con- star (in his reflecting telescope of 20 feet focus), the structed for the Chinese Government by the Jesuit height of which he estimated at more than four millions missionaries of the seventeenth century. The circles of of miles ! Brandes and Benzenberg, however, found

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the instruments of the thirteenth century are divided into from 22 meteors which they mutually observed in 1798, 365) degrees to correspond to the days of the year, each heights varying between 6 and 140 miles. Brandes indegree being subdivided into hundredths, but the later stituted some further observations in 1823, and of 62 instruments have their circles divided into 360 degrees. meteors available for calculation 55 were found to have

heights between 30 and 70 miles. On August 10, 1838,

M. Wartmann, at Geneva, followed up Brandes's inquiries, THE HEIGHTS OF METEORS.

and derived the average height of the meteors seen on IT T is perhaps surprising that the heights of meteors, and that occasion as 550 miles, and their velocity 240 miles a

especially of that class known as fireballs, were not second. These values, compared with modern observdetermined with any accuracy until the near approach of ations, were far less accurate than Brandes's earlier ones. the present century. It is true that a few individual

It is not proposed in this paper to deal fully with the attempts were made in this direction but, considering the average heights of meteors, for that has been discussed large number of brilliant meteors which appear every by several authorities. The values are about 76 and 31 year, it is curious that some systematic attempts were not miles respectively for the mean elevations at appearance made at a much earlier date in this direction. It must, and disappearance. In the case of fireballs, however, however, be remembered that many years ago there were they penetrate much deeper into our atmosphere than

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