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The wet string, while it is for the purpose of keeping the through these holes is not diffused in any harmful manne. condenser c charged a perfect conductor, is nevertheless, The large box at the back is a case 5 ft. long, filled when this discharges at E' and B, practically a perfect bran which stops the bullets gently without marking them. insulator ; if it were replaced by wire then C would also The little condenser is just below the rectangular pa wholly or partially discharge itself by B and E'. Finally, longation of the photographic box, the large condensers in avoiding all lenses one is free from the considerable the vertical square sheet seen just to the right. The absorption of the more refrangible rays which sparks pro- electrical machine used to charge the condensers is see vide in great abundance, and which are largely absorbed on the table. It is a very beautiful 12-plate Wimstar by glass. On the other hand the photograph is a mere machine made by Mr. Wimshurst and presented to shadow, but this is no drawback, for the bullet itself is on Physical Laboratory. This machine not only works either system a mere silhouette, whereas the atmospheric certainty but is so regular in its working thalsh phenomena are more sharply defined, and their character electrometric apparatus is necessary. All that has to : is more clearly indicated without lenses than is possible done is to count the number of turns of the handle while when they are employed.
are required to produce the sparks at Eand E' where Fig. 5 is a photograph of the apparatus set up in one gap at B is not joined, and to count the number which of the passages in the Royal College of Science, in are sufficient to produce a spark at E when the gapa: which the experiments were made. It is apparently of is suddenly closed. Then if the rifle is fired after 20 the rudest possible construction. The rifle seen on the number of turns between these, but by preference nézra left of the figure is of course made to rest freely on six the larger than the smaller number, the potential will be points, in order that its position every time it is fired may l right, the spark E, inside the box, and the spark E'.wb
be the same. The bullet then traverses precisely the is in sight outside the box, will be let off, and is same course, so that wires placed in the line between holes plate is exposed a photograph will be taken. If by chane in two cards made by one shot will be hit by the next. The the E' spark is not seen then there is no occasice two wires which the bullet joins as it passe's by are set up waste the plate, another bullet may be fired in the box seen in the middle of the figure with the lid resetting the wires and the result will be as good asi propped up so as to show the interior. The photographic shot bad not failed. When all is in order a failure of plate is on the left-hand side and the spark when made kind is very rare. I also arranged a tube in the sick is just within the rectangular prolongation on the right the box with a pocket telescope fixed in it and focus hand side. Paper tubes with paper ends are placed on the wires. If a piece of white card or paper is plas on each side of the box to allow the bullet to enter and in the line of vision and so as to be illuminated be leave, and yet not permit any daylight to fall directly spark let off as above described but preferably on the plate. All is black inside, and so the nearer the card, the bullet will be seen by any one los small amount of light which does enter the box through the telescope. I took this down, however
Six independent points of support are required for a geometrical clamp. once, as the photograph showed more than could In this case a V support near the muzzle supplied two, a V support near the breach two more points, the rifle was pressed forward until a projection under the muzzle rested against the front V, thus allowing freedom of recoil, but
rifle with a coil of wire upon it is the one in which otherwise preventing all uncertainty of position except that due to rotation revolving mirror was fixed, and in which the trails in the V's which is made impossible by the sixth point, that is, the lower end sparks made near the door at the end of the pas of the stock resting sideways against a leather covered wooden bracket fastened to the same table to which the V's were attached.
were photographed. The apparatus for photogen
bullets was put together and set up by Mr. Barton, a was put together. It was taken to see if the idea would ident, whose very skilful help in the matter and after- practically succeed, merely using for the purpose bits of
wire and other things to be found in any laboratory, which were set up in a dark room in less than an hour. The first shot was successful, but the sharpness of the photograph is not what it might be, owing to the fact that I used, for the sake of the brilliant light, a spark taken between magnesium terminals. However, the bullet is clearly enough defined, as are the wires which it has just struck. This is a photograph of a pistol bullet travelling only 750 feet a second. You will notice that unlike that taken by Prof. Mach, which represented a shot going at a much higher speed, this photograph shows no atmospheric phenomena surrounding the bullet. I would only add, in connection with tbis photograph, that by some accident the wad remained attached to the bullet in this case forming the enlarged tail. I do not know if this often happens; it must, if it does, seriously disturb the flight of the projectile, and introduce an anomaly
that might not easily be accounted Fig. 6.
The next photograph, Fig. 6, shows wards during the experiments I sound of very great | a bullet which has just left a Martini-Henry rifle. This value.
is taken with the apparatus in its latest form, and the bullet
FIG. 7. The first photograph which I am able to show was appears perfectly sharp. There is no sign of any movetaken at Christmas, before the apparatus just described ) ment whatever in so far as the bullet itself is concerned. But now that we are dealing with a higher speed, namely, will be smaller, and the angle between Lp and MD will be 1295 feet a second, there is evidence of the movement of come less, while when the velocity is made less the reser the bullet in the form of a wave of compressed air in front happens, until at last Aa Bb, &c. = AD Bp, &c., and the and of other waves at the side of and behind the bullet. when they exceed these quantities no lines Lo Moc I shall explain this in a moment, but I would rather be drawn touching all these circles, there is no first show another photograph, Fig. 7, of a bullet travel Surface which the disturbances from all the success ling at a still higher speed, a magazine rifle bullet points can conspire to produce, and the consequence travelling about 2000 feet a second, in which these air there is still water. waves are still more conspicuous, and in which a glance Now consider the case of a bullet moving through të is sufficient to make it evident that the waves are much air. Here again we are dealing with a case in wbid. more inclined to the vertical than in the previous case. wave cannot travel at less than a certain speed whics
Now as it may not be evident why these waves of air obviously the velocity of sound (1 100 feet a second 12 are forme, why their inclination varies with the speed, ordinary circumstances), but, as in the case of surine or why existing they are visible at all, a short explanation waves on water, higher speeds are possible when the w7! may not be out of place, more especially as they form the is one of very great intensity. The conditions in the most interesting feature in the remaining photographs 'cases are therefore very nearly parallel ; if the bule: that I have to exhibit, which cannot, as a matter of fact, travelling at less than the minimum speed no vale be properly interpreted without frequent reference to should be formed—the pistol bullet at 750 feet a secara them.
did not show any-if the bullet is travelling at higher species I would first ask you to examine some still water into than 1100 feet a second waves should be formed yt which a needle held vertically is allowed to dip. If you should include a sharper angle as the speed is made move the needle very slowly not a ripple is formed on increase. This was found to be so in the case of the the surface of the water ; but as the needle is moved Martini-Henry and the magazine rifle bullet. more quickly at first a speed is reached at which feeble The curved form of the wave near the apex is due to the waves appear, and then as the speed increases a swallow- fact that when it is very intense, when the compressione tail pattern appears, the angle between the two tails be- very great, the velocity of travel is greater and, immediate come less as the velocity gets higher. Now in the case in front of the bullet, the air is compressed to so greza of water-waves the velocity with which they travel exent that the wave at this part can travel at the speede depends on the distance between one and the next, and the bullet itself. for a reason into which I must not now enter either very i The reason why the waves should be visible at ala long or very short waves travel more quickly than waves not difficult to follow. Consider a shell of compressed of moderate dimensions. If they are about two-thirds of air though which rays of light from a point are made an inch long they travel most slowly-about 9 inches a traverse. These rays travel in straight lines, except wher second. Now so long as the needle is travelling less they meet a mediuin of different density, and the des quickly than this no disturbance is made ; but when this this is and the more nearly they meet this at a great speed is exceeded the swallow-tail appears. Suppose, for incidence the more they will be bent towards the perperc example, the velocity of the needle to be double the mini- cular. In comparison with water or glass a layer of ac mum wave velocity for water, i.e. let the needle move at 18 pressed air has very little refractive power, and s0:23 inches a second, and let it at any moment have arrived which strike the shell anywhere except at the extent at the point Þ, Fig. 8. Then any disturbance, started edge are practically uninfluenced in their courses
strike the plate practically in the same place that the would do if the shell of compressed air had not been
when it was at the point A, must have travelled as far as traversed. But those rays ab, ab, Fig. 9, which strie the circle aaa in which Aa is half Ap, similarly for any shell of air almost tangentially are bent inwards slig! number of points BC, &c., between A and p any dis- b and again at c, having traversed what is equivale turbance must have travelled as far as the corresponding 'wide angle prism, and strike the plate at e, leaving the circles bb, cc, &c., the result is that along a pair of lines, d, where they would have gone had they not been res PL, PM, touching all the circles that could be drawn in dark ; moreover at e they meet other rays which bave this way, a wave will be found, and it is clear that as the 'hardly at all refracted since they have passed sa velocity of the point is made greater the successive radii into the shell and out again, and therefore e is like Aa Bb, &c., will become in proportion to Apless, the circles ) illuminated. The consequence is that a wave of
m pressed air gives rise to an image on the plate, in published a catalogue of the plants cultivated there, together hich there is a dark line and a light line within it. with a brief history of the garden. imilarly a wave of rarefaction must produce a light ne with a dark one within it. An examination of the
The German Government has established a biological hotograph Fig. 7 will make it evident that not only is the
Institute on the island of Heligoland, and has appointed ead wave a wave of compression, but the wave, which Dr. Kuckuck its botanical director. . tarts from the end of a kind of vena contracta behind the
PROF. SCHWEINFURTH landed at Port Said on January 7, ullet, is also a wave of compression. It is a curious fact
for an expedition into Upper Egypt which is intended to extend rhich requires explanation that the head and tail waves Le not parallel to one another, and they do not show any
over several months. Dr. D. Riva, who accompanied Schweinign that they would become parallel if they were continued furth on his last journey, has undertaken an expedition to ndefinitely. This can only be due to either the tail of Eastern Africa in the vicinity of the river Giuba. he bullet travelling considerably faster than the head, or
The moss herbarium of Dr. Rehmann and the Hepaticao the actual velocity of propagation of the tail wave being
herbarium of Dr. Gottsche have passed into the possession of ess than that of the head wave. The effect observed is true and is not optical, being neither due to the refractive
the Botanical Museum of Berlin ; the Botanical Museum of the effect of the outer shell disturbing rays which are
University of Vienna has acquired the moss-herbarium of tangential to the inner shell, nor to an effect of perspective, Hoppe ; and the Botanical Institute of the German University for though the projection of a cone from a point upon a at Prague the greater part of the valuable library of Prof. plane is only seen of the proper angle, when the per Willkomm. pendicular, dropped from the point upon the plane, passes through the vertex of the cone, yet when, as in the case
The Reale Istituto Veneto di Scienze, lettere ed arti proposes of Fig. 11, where it passes within both cones, and more the following prize subjects :-(1) A lithological, mineralowithin the outer one than the inner one, the effect is to gical, and chemical investigation of the rocky, sandy, earthy, make the projections of both of a greater obtuseness, and and saline materials brought down under various conditions by of the outer one to a greater extent than the inner one ; one of the chief rivers of Venetia from the Alpine valleys, and nevertheless an examination of the amount of this effect |
deposited at various distances from the base of the Alps to the of perspective made by Mr. Barton showed that the
sea (prize, 3000 lire, date December 31, 1893). (2) A comdistortion was not sufficient to be noticeable, as the
pendium of the history of mathematics, with a mathematical difference in the acuteness of the cones certainly is.
chrestomathy containing extracts from mathematical works of (To be continued.)
antiquity, the middle ages, the renaissance, and recent times down to Gauss (indicating in each case the reason for introducing the extracts), (prize and date the same). Papers may be
written in Italian, Latin, French, German, or Englislı, and are NOTES
to be sent in to the secretary with motto and sealed packet. ADMISSION to the Croonian Lecture, which Prof. Virchow,
SIR ANDREW BARCLAY WALKER, who died on Monday, did as we have already announced, is to deliver before the Royal
much to promote intellectual life in Liverpool. The University Society at 4.30 p.m. on the 16th inst., will be by ticket, which
College of that city has good reason to remember him as one of may be obtained from the assistant secretary by introduction of a Fellow of the Society.
its most generous benefactors. He assumed the entire pecuniary
responsibility for the erection of the Walker engineering laboraTHERE will be widespread regret at the announcement which tories, which cost about £20,000. we now make that the distinguished geologist, Prof. K. A.
Mr. O. M. EDWARDS, who was appointed to investigate the Lossen, of Berlin, died there on the 24th ult. He had been
various conditions which have to be taken into account in conailing for some time, and suffered severely before he entered
nection with the proposal for the establishment of a Welsh into his rest. In spite of the dealness which necessarily re
University, has completed his inquiries and forwarded his restricted his intercourse with men of science, he had formed a
port to the Vice-President of the Committee of Council on wide circle of friends who learged to appreciate the simplicity,
Education. A writer in the University Correspondent says the candour, and geniality of his character, while at the same time
report is practically a pamphlet of about eighteen octavo pages, they came to respect and admire more and more his wide range
containing a short account of the origin and progress of the of knowledge, and that marvellous and apparently intuitive per
educational movement in Wales, and intended to supplement ception of the true characters of rocks which made him probably
the information already possessed by the Department of Educathe best field-petrographer in Germany.
tion on this head. It contains a succinct epitome of the various We have received news of the death of Cav. Giuseppe
schemes proposed- the Shrewsbury Charter, the proposals of Antonio Pasquale, for many years professor of botany in the
Dr. Roberts and Prof. Evans ; gives the state of efficiency of University of Naples, and director of the botanic garden. Prof.
Lampeter and the three Welsh colleges ; contrasts them with Pasquale was the author of numerous articles on botany and
those at Leeds and Manchester ; and points out how far, more cognate subjects. His earliest works of which we have
or less, the Welsh institutions are prepared and adapted, in cognisance were on the flora of Capri (1840), and the fora of
point of staff, students, accommodation, and appliances, to Vesuvius (1842). In 1869 he published a more complete
receive similar powers, " Flora Vesuviana, confronte con quella dell'isola di Capri." The Municipal Council of Paris has been giving names to He appears to have been appointed to the post of director of some new streets, and changing those by which various old streets the Naples Botanic Garden in 1866, and the following year he have hitherto been known. The names selected for use are for
the most part those of illustrious Frenchmen, and it is significant * It may be worth while to point out that the dark and light lines are, and ought to be, parallel to one another as soon as they are so far away from the
that among them are some well-known men of science. The shadow of the bullet as to be practically straight lines. For if the thickness Rue du Battoir, for instance, is henceforth to be called the Rue of the shell is divided up into a series of elements the ray passing through any one of these will meet with a refractive medium, which is less effective
Quatresages, in memory of the famous anthropologist ; and the the diameter of the part of the shell considered is greater, while the Rue Claude Vellefaux becomes the Rue Charles-Robin, in refractive angles of the elementary prisms become inclined more so as to compensate for the diminished density.
memory of the great physician. A new street is called after
Ernest Renan. This is only one of many indications of the re account of the various researches now in hand, among was spect in which science is held in France. We shall probably are included investigations relating to rainfall, suas have to wait some time before it is decided by the municipal fog, &c. It also contains particulars relating to the au authorities of London that streets shall be known by the names, done in cataloguing books and pamphlets, and also a da say, of Darwin and Joule.
summary of expenditure. A special note contains an acu
of the anemometer comparisons carried out by Mr. !! The atmospheric disturbance referred to in our last issue as
| Dines, with the aid of a grant from the Council. crossing this country on Tuesday, February 21, reached the English Channel on the following day; afterwards its progress
The Meteorological Council have just issued a summer eastwards was unusually slow, and north-west winds belonging | the Weekly Weather Report, 1892, containing, among to the rear of the disturbance were experienced. Frost occurred other information of importance to agricultural and hits during the night of the 22nd in many parts, and towards the meteorology, an appendix showing the rainfall'and mean tema close of last week the daily maxima fell below 40°, except in ture for the 27 years 1866 to 1892, for each of the 12 ders the extreme west and south-west, while in the midland counties
into which the United Kingdom is divided for the purp frost continued throughout the day, and hail and snow occurred
weather forecasts. The values show that the average size in many places. After a temporary improvement in the south
for the whole of the British Islands is 349 inches ; '13 and south-east districts on Saturday, a deep depression reached
wheat-producing districts the average fall for the years our south-west coasts from the Atlantic, causing strong gales on
inches, while for the grazing, &c., districts it is 416 izle Sunday, and very severe snowstorms in Scotland, with heavy
The wettest district is the west of Scotland, where the area rain in other parts of the country, the fall exceeding an inch and
annual rainfall is 45.5 inches, and the driest is the east of Es a quarter on the north-east coast. By Sunday evening the dis
land, where the average amount is 25.8 inches. The last turbance had reached the north-east of England, where the
the year 1892 varied considerably in different localra, i barometer had fallen to 28.6 inches; this depression was pre
wettest district during the year was the north of Scots ceded by severe frost in Scotland, the minimum temperature
where the fall was 5:6 inches in excess of the average stad recorded at Nairn being as low as 1ro. On Monday a north the south-west of England the deficiency was 12 5 inches -westerly gale was blowing in Scotland, accompanied by
regards temperature, the average for the whole area for 123 snow, and on the same day a new depression arrived over years (omitting the Channel Islands) was 484, and the 20 the south-west of England, accompanied with further heavy
difference of temperature between the wheat-producing rainfall in the southern half of the kingdom, and strong winds
grazing districts scarcely amounted to a degree. The avere and gales in the English Channel ; frost also occurred in many value for the whole area during 1892 was 1°.6 below the parts. After these gales had subsided, the weather still remained for the 27 years ;- there was a deficiency in every district in a very disturbed and unsettled condition, The Weekly that year, the greatest amount being 2°•3 in the east of . Weather Report issued on February 25 showed that the land, and the least, oog in the south of England ; in fac temperature for that week was generally 1° to 2° below the was the coldest year experienced since 1879. mean in Great Britain, and 3° to 4° below in Ireland ; also that An electrical actinometer was used by Messrs. Els the rainfall was much in excess of the average in the southern | Geitel, of Wolfenbüttel, in their measurements of and eastern parts of England.
ultraviolet radiation. The instrument, as described in JE - The Report of the Meteorological Council for the year ending
mann's Annalen, was based upon the action of ultravida March 31, 1892, just presented to Parliament, reviews the work
in accelerating the dissipation of an electric charge to of the office under four heads : (1) Ocean Meteorology. The
cathode of amalgamated zinc. By exposing a plate 19 charts for the Red Sea were in an advanced state, and the extrac
metal to the light from a stream of sparks from an ad tion of data for the current charts of the Atlantic, Pacific, and
coil at various distances, and determining the dissipaane & Indian Oceans, and of data referring to the southern ocean,
negative charge imparted to it, this was proved to be was being actively carried on. In this branch of the work the
function of the light intensity. In its portable form the supply of instruments to ships is supplemented by the supplies
ment consists of a cylinder which can be directed to at to remote stations, when favourable opportunities occur. (2)
sun, and into which a charged sphere of amalgamated a Weather Telegraphy and Forecasts. An important station has
introduced by means of an insulating handle. The fa been established at the North Foreland, and the work generally
potential during a few seconds' exposure is determined by a in this branch continues to increase ; both the Daily and
of an Exner electroscope. Messrs. Elster and Geisel Weekly Weather Reports have been extended and improved.
made observations for each month in the year, and food Weather forecasts are prepared three times daily ; the total
ultraviolet radiation to exhibit an inverse relation to percentage of success of the Sh. 30m. p.m. forecasts which appear
spheric electricity. Comparisons were also made of the in the morning newspapers was so, being 2 lower than in 1890
at various heights above the sea-level, the stations bet 91. The results were best in England south, and worst in
summit of the Sonnblick (3100 m.), Kola-Saigern, Scotland west. The percentage of success of the forecasts
adjoining valley (1600 m.), and Wolfenbüttel (80 m issued during haymaking was 89 per cent. Although these fore.
found that 40 per cent. of perpendicular ultraviolet raps casts are issued solely for the benefit of farmers, the Agricultural
space reached the level of Sonnblick, 23 per cent of these Department does not at present aid in their dissemination.
absorbed before reaching the next station, and only 47 p (3) Land Meteorology of the British Isles. Under this head are
of the remainder arrived at the level of Wolfenbüttel included all observatories, anemograph stations, and volunteer Ten years ago there was some correspondence in stations, necessary for the study of the periodic variations of the on the subject of snow.rollers. The phenomenon des $1. meteorological elements, and of climatology. Among the pub. | to occur very often, so that some interest attaches to lications we may specially mention the “ Harmonic Analysis of cation in Science (February 3), describing an instance merken the Hourly Observations at British Observatories,” which is year at Milledgeville, Ohio. Mr. W. S. Ford says ter probably the first systematic publication of the description that morning of January 30, 1892, the clean level fields sur has hitherto been brought out by any of the established meteoro- that town were covered with balls of snow, varying logical institutions. (4) Miscellaneous. This head gives an three to five inches long and from one to two