« PreviousContinue »
great difficulty in the case of soft iron, and is not observed at all in the case of manganese steel. A fairly approximate numerical measurement may be made in this way: Take a block of iron or steel on which a groove is cut, and in this groove wind a coil of copper wire insulated with asbestos; cover the coil with many layers of asbestos; and finally cover the whole lump of iron or steel with asbestos again. We have now a body which will heat and cool comparatively slowly, and which will lose its heat at a rate very approximately proportional to the difference of temperature between it and the surrounding air. Heat the block to a bright redness, and take it out of the fire and observe the resistance of the copper coil as the temperature falls, due to the cooling of the block. Plot a curve in which the abscissæ are the times, and the ordinates the logarithms, of the increase of resist. ance of the copper coil above its resistance at the temperature of the room. If the specific heat of the iron were constant, this curve would be a straight line ; if at any particular temperature latent heat were liberated, the curve would be horizontal so long as the heat was being liberated. If now a block be made of manganese steel, it is found that the curve is very nearly a straight line, showing that there is no liberation of latent heat at any temperature, If it is made of nickel steel with 25 per cent. of nickel, in its non-magnetic state, the result is the same-no sign of liberation of heat. If now the block be made of hard steel, the temperature diminishes at first; then the curve (Fig. 13) which represents the lemperature bends round: the temperature actually rises many degrees whilst the body is losing heat. The liberation of heat being completed, the curve finally descends as a straight line. From inspection of this curve it is apparent why hard steel exhibits a sudden accession of brightness as it yields up its heat. In the case of soft iron the temperature does not actually rise as the body loses heat, but the curve remains horizontal, or nearly horizontal, for a considerable time. This, again, shows why, although a considerable amount of heat is liberated at a temperature corresponding to the horizontal part of the curve, no marked recalescence can be obtained. From curves such as these it is easy to calculate the amount of heat which becomes latent. As the iron passes the critical point it is found to be about 200 times as much heat as is required to raise the temperature of the iron i degree Centigrade. From this we get a very good idea of the importance of the phenomenon. When ice is melted and becomes water, the heat absorbed is 80 times the heat required to raise the temperature of the water 1 degree Centigrade, and 160 times the heat required to raise the temperature of the ice by the same amount. The temperature of recalescence has been abundantly identified with the critical temperature of
magnetism.?. I am not aware that anything corre-falling, they become again magnetic, the effect of the sponding with recalescence has been observed in the direction of their axes is apparent. But Weber's theory case of nickel. Experiments have been tried, and gave does not touch the root of the matter by connecting te a negative result, but the sample was impure; and magnetic property with any other property of iron, not the result may, I think, be distrusted as an indication of does it give any hint as to why the moment of the molewhat it would be in the case of pure nickel. The most cule disappears so rapidly at a certain temperature. probable explanation in the case of iron, at all events, Ampère's theory may be said to be a development of appears to be that when iron passes from the magnetic tó Weber's: it purports to state in what the magnetism of the non-magnetic state it experiences a change of state of the molecule consists. Associated with each molecule is comparable importance with the change from the solid to a closed electric current in a circuit of no resistance: the liquid state, and that a large quantity of heat is ab- each such molecule, with its current, constitutes Weber's sorbed in the change. There is, then, no need to suppose magnetic molecule, and all that it can do they can do chemical change; the great physical fact accompanying But the great merit of the theory, and a very great one the absorption of heat is the disappearance of the capacity it is-is that it brings magnetism in as a branch of elec for magnetization.
tricity ; it explains why a current makes a magnetizable What explanations have been offered of the phenomena body magnetic. It also gives, as extended by Weber, an of magnetism ? That the explanation must be molecular explanation of diamagnetism. It, however, gives no hint was early apparent. Poisson's hypothesis was that each of connecting the magnetic proporties of iron with any molecule of a magnet contained two magnetic fluids, other property. Another difficulty is this: When iron which were separated from each other under the influence ceases to be magnetizable, we must assume that the maleof magnetic force. His theory explained the fact of mag- cular currents cease. These currents represent energy. netism induced by proximity to magnets, but beyond this we should therefore expect that, when iron ceased to be it could not go. It gave no hint that there was a limit to magnetic by rise of temperature, heat would be liberated; the magnetization of iron-a point of saturation ; none of the reverse is the fact. hysteresis ; no hint of any connection between the mag So far as I know, nothing that has ever been proposed netism of iron and any other property of the substance; even attempts to explain the fundamental anomaly. Why no hint why magnetism disappears at a high temperature do iron, nickel, and cobalt possess a property which we It does, however, give more than a hint that the perme- have found nowhere else in nature? It may be that it ability of iron could not exceed a limit much less than its lower temperatures other metals would be magnetic, but actual value, and that it should be constant for the mate of this we have at present no indication. It may be that, rial, and independent of the force applied. Poisson gave as has been found to be the case with the permanent his theory a beautiful mathematical development, still gases, we only require a greater degree of cold to extend useful in magnetism and in electrostatics.
the rule to cover the exception. For the present, the Weber's theory is a very distinct advance on Poisson's. magnetic properties of iron, nickel, and cobalt stand as He supposed that each molecule of iron was a magnet exceptional as a breach of that continuity which we are in with axes arranged at random in the body; that under the habit of regarding as a well-proved law of Nature. the influence of magnetizing force the axes of the little magnets were directed to parallelism in a greater degree as the force was greater. Weber's theory thoroughly
NOTES ON A RECENT VOLCANIC ISLAND explains the limiting value of magnetization, since no
IN THE PACIFIC. thing more can be done than to direct all the molecular axes in the same direction. As modified by Maxwell, or
N 1867, H.M.S. Falcon reported a shoal in a position IN
in about 20° 20' S., and 175° 20' W., or 30 miles west with some similar modification, it gives an account of of Namuka Island of the Friendly or Tonga Group hysteresis, and of the general form of the ascending curve In 1877 smoke was reported by H.M.S. Sappia to be of magnetization. It is also very convenient for stating rising from the sea at this spot. some of the facts. For example, what we know regarding In 1885 a volcanic island rose from the sea during a the effect of temperature may be expressed by saying that submarine eruption on October 14, which was first rethe magnetic moment of the molecule diminishes as the ported by the Janet Nichol, a passing steamer, to be 2 temperature rises, hence that the limiting moment of a miles long and about 250 feet high. magnet will also diminish ; but that the facility with The U.S.S. Mohican passed it in 1886, and from calculawhich the molecules follow the magnetizing force is also tion founded on observations in passing, gave its length increased, hence the great increase of re for small forces, as 110 miles, height 165 feet. The crater was on the and its almost instantaneous extinction as the temper- eastern end, and dense columns of smoke were rising ature rises. Again, in terms of Weber's theory, we can from it. state that rise of temperature enough to render iron non In 1887 the French man-of-war Decres reported its magnetic will not clear it of residual magnetism. The height to be 290 feet. axes of the molecules are brought to parallelism by the In the same year an English yacht, the Sybil, passed il. force which is impressed before and during the time that and a sketch was made by the owner, H. Tufnell, Esq. the magnetic property is disappearing they remain which is here produced. parallel when the force ceases, though, being now non The island has now been thoroughly examined and magnetic, their effect is nil. When, the temperature mapped, and the surrounding sea sounded by H.M. I have only recently become acquainted with the admirable work of
surveying-ship Egeria, Commander Oldham. M. Osmond on recalescence. He has examined a great variety of samples
It is now ito mile long, and 1 of a mile wide, of the of steel, and determined the temperatures at which they give off an excep- shape given in the accompanying plan. The southern tional amount of heat. Some of his results are apparent on my own curves, portion is high, and faced' by cliffs on the south, the referring to my Royal Society paper, there is, in Fig. 38, a hint of a second summit of which is 153 feet above the sea. A long fat small anomalous point a little below the larger one. Figs. 38 and 38A, we see that the higher the heating, the lower is the point
And, comparing stretches to the north from the foot of the hill. of recalescence ; both features are brought out by M. Osmond
The island is apparently entirely formed of ashes and quantity of carbon I would explain provisionally by supposing this steel to there, especially on the verge of the hill. double recalescence observed by M. Osm und in steel with a moderate cinders, with a few blocks and volcanic bombs here and be a mixture of two kinds which have different critical temperatures. Although M. Osmond's method is admirable for determining the temperature
Under the action of the waves, raised by the almost of recalescence, and whether it is a single point or multiple, it is not constant south-east winds, this loose material is being used is inclosed in a fube of considerable mass, which cools down at the rapidly removed ; continual landslips take place, and same time as the sample experimented upon.
Commander Oldham is of opinion that the original
Flat Icand with. ridge *
M.S.S EGERIA, 1889.
JU Cables ar 1 Sea Mile
summit was some 200 or 300 yards southward of the speaking of forecasts based on telegraphic reports, and present highest cliff, and that the shallow bank stretching emanating from a central office. In every country, withto the south represents the original extension of the out exception, where forecasts for distant countis island.
provinces are issued from headquarters, the complains As far as can be judged from Mr. Tufnell's sketch from from outlying stations, of occasional failure, are freques the north-west and that of the Egeria from the south-enough. south-east, considerable changes have taken place in two The fact is that at individual stations the percentage years, the different summits shown in the former having of success may be highly satisfactory, as at Mr. C E disappeared as the sea has eaten away the cliffs.
Peek's observatory at Rousdon, Lyme Regis. The The flat to the north seems to be partly due to redis. results for this point appeared in the Times of January tribution under the lee of the island of the material 14, and are as follows: removed from the southern face. It is crossed by curved ridges from 3 to 12 feet high, which Commander Oldham 1884 ... 587 ... 690 ... 20'0 ... 110 ... 734 - too. 97 considers to have been formed as high beaches during 1885
70'0 ... 8o'o
12'0 ... So... Soo ... 120 ... 81 spring tides and strong winds, the flat ground between 1886 ... 730
90 850. 8070 them, almost at the level of the water, being deposited 1887 ... 750 830 90 So 82'0 IID. 70 under normal conditions of weather.
1888 ... 810 890 ... 50 ... 60 ... 89'0 .. 70...43 The island is thus gaining on one side, while losing on In this, Col. I is percentage of reliable wind and weather the other, but when the high part has gone, this partial
wind only. recovery will probably cease.
wind doubtful. A little steam issuing from cracks in the southern cliffs
wind unreliable. was the sole sign of activity, but a pool of water at a
reliable weather. temperature of from 91° to 113° F., water which rose in a
weather doubtful. hole dug in the flat of a temperature of 128° F., and a
unreliable temperature of 100° F. in a hole dug half-way up the slope, On the other hand, at other points the forecasts may also show that the island still retains heat near the sur- be frequently unsuccessful. face. The water is sea-water that has filtered through the In one important particular not only our own Office loose ashes, and it rose and fell with the tide.
but all other Offices in Europe, signally fail, and that is It appears by the condition of the flat that the island the quantitative prediction of rain. No one is able 3has neither risen nor subsided during the past two or parently, to predict whether the amount of rainfall three years.
the morrow will be a tenth of an inch or a couple of It will be interesting to watch the ultimate fate of this inches. No sudden floods have ever yet been foretold
. last addition to the Pacific isles, but it seems probable By this we are not speaking of predicting the approach that its existence as an island will be short unless a hard of floods to the lower valleys from rain which has already core is yet revealed.
fallen on the upper reaches of a river, for that is na The soundings between Falcon Island and Namuka meteorological prediction at all. show that they are separated by a valley 6000 feet deep. With the necessarily incomplete character of the in
Metis Island, 73 iniles north-north-east of Falcon formation reaching head-quarters, the wonder is that the Island, is another volcanic cone that appeared a few Office can attain such success as it does. The main years before the latter, but has not yet been examined. deficiency in the information is in its quantity, and this
W. J. L. WHARTON. seems to lie at the door of the Postal Telegraph Office
which insists on being paid for its telegrams. If meteoro
logical messages were transmitted gratis, we might expect WEATHER FORECASTING.
to hear at frequent intervals from our outposts, instead
of twice, or, at most, thrice in the twenty-four hours: in in , sign of abating. The January number of the Kew cost of more telegrams being prohibitive. It is self Bulletin is devoted to an account of Herr Nowack's so evident that such an amount of information is quite incalled “weather plant," and its failure as an indicator sufficient. The weather will not abstain from changing either of coming weather or of earthquakes. Very
Very because the hour for a telegraphic report has not arrived. recently a lively correspondence has been carried on in The information contained in the telegrams is ako the daily press on the merits or demerits of the forecasts deficient in quantity, for the reporters cannot, within the issued by the Meteorological Office. Accordingly, some prescribed form of their messages, communicate all k remarks on the subject in the columns of NATURE may impressions which the ever-varying appearance of the not be out of place.
sky may have conveyed to their minds. A skilled cload One critic says that the forecasts are little better than observer, who has leisure to practise his powers, is one haphazard guesses, and that the money devoted to them able to form a very correct idea of what is coming for would be better spent on an additional lifeboat or two the region bounded by his own horizon, but he is quite on the coast. Another says the forecasts are not worth unable to give the benefit of his observations and espert the paper they are printed on, and wishes that the Office ence to a friend in another county by telegraphing the published in the newspapers fuller accounts of the weather information. reported from the coasts.
The greatest want which the Office finds in its observers The fact is that the Office is compelled by public is skill in cloud observation, and it appears to be the cz opinion to issue forecasts. The public will have its that a cloud observer nascitur non fit, and that it is nest. forecasts, as in 1867 it would have its storm-warnings, to impossible to teach the art to a new hand, at least by notwithstanding the reluctance of meteorologists to issue correspondence. either the one twenty years ago or the other at present. Instrumental records of the phenomena taking place ia It can hardly be doubted that, for these islands at least, the higher strata of the atmosphere are of course anat conscientious meteorologists would be disposed to agree tainable, and it is only by carefully watching the upper with Arago, who said in 1846, and printed it in italics clouds that we can gain any notion of changes taking in the Annuaire du Bureau des Longitudes : " Jamais
, place up there, but, by means of such watching, No quels que puissent être les progrès des sciences, les Clement Ley is able to predict with nearly perfece savants de bonne foi et soucieux de leur réputation ne se certainty the weather for the Midlands-his own nes hasarderont à prédire le temps." We are, of course, bourhood.
43 50 48 53
42 27 39 32 40 41 24
II 17 10 9
It must always be remembered that the forecasts are in the picturesque surroundings of those old homes of drawn for districts, not for individual stations; and disre- learning. They attract attention and interest by their karding the amount of correctness claimed by the Office situation amid scenes and traditions of which the whole by its own checking of its work, they attain a very credit- English-speaking race is proud. Bedford College has able amount of success when tested by independent had no such advantages. London institutions are reobservers. This happens even in the summer-time, the garded as either Imperial or parochial-as too large or too very season at which a recent critic said that the forecasts small to interest its citizens as such. Bedford Square iar one month, if shuffled about, and drawn at random compares unfavourably with the “backs,” and it is imfrom a bag, would suit just as well for the next! This is possible to regard York Place with that gush of emotion Froved by the results of the hay harvest forecasts, which which "the High" sets free. Thus it is that, although are deduced from the reports of the recipients, practical Bedford College has been at work since 1849, and though tgnculturists.
one in every four of the whole number of women who The following is the table for the season of 1888, the have gained degrees of the University of London has latest for which the figures are available :
been a student in its classes, the work of the College does not yet receive the meed of public appreciation which it
has fairly earned. Bedford College is for women what Percentages.
University and King's Colleges are for men. It provides,
within easy reach of all Londoners, an education which is Districts Names of stations.
tested by the severe standard of the University of London, and bears the hall-mark of success. One-third of its students are aiming at degrees, and their presence
in the class-rooms, their work in the examination-hall, Scotland, X Golspie and Munlochy
guarantees the quality of the teaching they receive to North Berwick, Glamis, Aberfeldy, and Rothiemay
class-mates who do not intend to face the same Engiund, N.E Chatton and Uleeby
ordeal. Science has for long been taught in Bedford Thorpe and Rothamsted Midland Counties. Cirencester and East Retford
College, but there has been a pressing need for better Lapland, S. - Horsham, Maidstone, and Downton 52
laboratories and class-rooms. These the Council has Sootland, w. Dumbarton, Islay, and Stranraer
now provided. A new wing has been built, dedicated to Izland, xw. Leyburn and Prescot SW, Bridgend (Glamorgan), Clifton,
the memory of the late Mr. William Shaen, who worked Glastonbury and Spring Park
long and devotedly for the College. About £2000 is (Gloucestershire) ... trebant, N. Moynalty and Hollymount
required to complete and fit up this building free of all
43 | 38 Moneygall, Kilkenny, Ardfert
debt, and Mr. Henry Tate, who had already given £ 1000 Abbey
to the fund, has promised to supplement it by a like
amount if the Council on its part can raise the other Every year the Office hears of farmers expressing their moiety of the deficit. It is too probable that this sum aterest in these announcements, and sending daily to will only be obtained by an exhausting effort, but surely the places where they are exhibited, to learn what they it is not too much to hope that the public may at last Juntain.
appreciate the importance of promoting the higher educaTo give an idea of the difficulty of obtaining accurate tion of women in London. In a northern manufacturing opinions from outsiders as to the value of storm-warnings, town the money would be forthcoming in a week. waich are a class of forecasts, it may be interesting to As regards the laboratories, it may be sufficient to say me some specimens of reports.
that Dr. W. Russell, F.R.S., is the Chairman of the Inquiries were made in 1882, from all the stations where Council, and that they have been built under his general signals are hoisted, as to their correctness and general supervision. They appear to be in all respects suited to utility
. From Tynemouth the answer was that these the purposes for which they are intended." The physical signals have been, and will be, an inestimable boon to our laboratory and lecture-room are on the ground floor. The seafaring population.” From South Shields, just opposite former has a concrete floor, and is well lighted, partly by Tynemouth, the reply to a recent official inquiry was windows, partly by a skylight. It looks out upon East har " the warnings were not a ha’porth of use, and that Street, and is therefore removed as far as possible from no dne minded them." Each answer merely represented the effects of the heavy traffic in Baker Street. The the private opinion of the person who uttered it. chemical laboratory is at the top of the house, and opens
The reader can see that there is some difficulty in into a class-room which is fitted with all the usual preking out the actual truth from such a heap of incon- conveniences for experimental illustration. TUOS statements as the foregoing are certain
to furnish. It is surely a hopeful sign that a College for the higher R. H. S. education of women should now be regarded as incom
plete unless it controls physical and chemical laboratories
specially designed and fitted for the delivery of lectures THE LABORATORIES OF BEDFORD
and the performance of experiments. These Bedford COLLEGE College now possesses. We can only
hope that it may
soon possess them free of debt. The Editor of NATURE BEDFORD COLLEGE, in York Place, Baker Street, will be happy to receive and forward to the College
which was one of the earliest institutions devoted to authorities any subscriptions which may be sent to him the higher education of women, is taking a leading part for that purpose. providing facilities for their instruction in science. Founded long before Oxford and Cambridge condescended to the "weaker sex * (which has since proved strong enough to attain to the highest place in the
STEPHEN JOSEPH PERRY, F.R.S. who defeat.
had a k has had to struggle not only against the inevitable servation of the eclipse of December 22, and that Father tifficulties due to its early foundation, but against the Perry had succumbed to dysentery. pathy of London Provincial towns feel that their Stephen Joseph Perry was born in London on August bonout is involved in the success of their institutions. 26, 1833, and received his early education at Gifford Hall The Colleges for women at Oxford and Cambridge share School." Having decided to enter the priesthood, he went
Classical Lipos), it is the result of the work of en ON the evening of January ha telegram from Demerata