not, indeed, admit of being certainly predicted by this law, since it not unfrequently happens that the sun shows few spots for several weeks together, in the very height of the time of spot-frequency, while on the other hamd it often happens that many and large spots are seen at other times. Nevertheless, this general law holds, that, on the whole, and taking one month with another, there is a variation in spot-frequency, having for its period an interval of rather more than eleven years. Now, the difference between a year of maximum spot-frequency, and one of minimum frequency, is very noteworthy, notwithstanding the exceptional features just mentioned, which show themselves but for short periods. This will be manifest on the consideration of a few typical instances. Thus, in the year 1837, the sun was observed on 168 days, during which he was not once seen without spots, while no less than 333 new groups made their appearance. This was a year of maximum spot-frequency. In 1843, the sun was observed on 312 days, and on no less than 149 of these no spots could be seen, while only 34 new groups made their appearance. This was a year of minimum spot-frequency. Passing to the next maximum year, we find that in 1848 the sun was observed on 278 days, during which he was never seen without spots, while 330 new spots made their appearance. In 1855 and 1856 together, he was observed on 634 days, on 239 of which he was without spots, while only 62 new groups made their appearance. The next maximum was not so marked as usual, that is, there was not so definite a summit, if one may so speak, to the wave of increase; but the excess of spot-frequency was none the less decided. Thus, in the four years, 1858, 59, '60, '61, the sun was observed on 335, 343, 333, and 322 days, on not one of which he was spotless, while the numbers of new groups for these four years were respectively, 202, 205, 211, and 204. The minimum in 1867 was very marked, as 195 days out of 312 were without spots, and only 25 new groups appeared. The increase after 1867 was unusually rapid, since in 1869 there were no spotless days, and 224 new groups were seen, though the sun was only observed on 196 days. The number of spots in 1870, 1871, and 1872, as well as their magnitude and duration, have been above what is usual, even at the period of maximum spot-frequency. From all this it will be manifest that we have a well-marked peculiarity to deal with, though not one of perfect uniformity. Next to the systematic changes already considered, this alternate waxing and waning of spot-frequency might be expected to be efficient in producing recognisable weather changes. Assuredly, if this should not appear to be the case, we should have to dismiss all idea that the sun-spots are weather-rulers. Now, from the first discovery of spots, it was recognised that they must, in all probability, affect our weather to some degree. It was noticed, indeed, that our auroras seemed to be in some way influenced by the condition of the sun's surface, since they were observed to be more numerous when there are many spots than when there are few or none. Singularly enough, the effect of the spots on temperature was not only inquired into much later (for we owe to Cassini and Mairan the observation relating to auroras), but was expected to be of an opposite character from that which is in reality produced. Sir W. Herchel formed the opinion that when there are most spots the sun gives out most heat, notwithstanding the diminution of light where the spots are. He sought for evidence on this point in the price of corn in England, and it actually appeared, though by a mere coincidence, that corn had been cheapest in years of spot-frequency, a result regarded by Herschel as implying that the weather had been warmer on the whole in those years. It was well pointed out, however, by Arago, that "in these matters we must be careful how we generalise facts before we have a very considerable number of observations at our disposal." The peculiarities of weather in a single and not extensive country like England, are quite insufficient to supply an answer to the wide question dealt with by Herschel. The weather statistics of many countries must be considered and compared. Moreover, very long periods of time must be dealt with. * When Herschel made his researches into this subject, the law of spot-frequency had not in this law, as some have since done, the explanabeen discovered. He would probably have found tion of the seven years of plenty and the seven years of famine typified by the fat kine and lean M. Gautier, of Geneva, and later MM. Arago and Barratt made a series of researches into the tabulated temperature at several stations, and for many successive years. They arrived at the conclusion that, on the whole, the weather is coolest in years of spot-frequency. But recently the matter has been more closely scrutinised, and it has been found that the effects due to the great solar spot period, although recognisable, are by no means so obvious as had been anticipated. These effects may be divided into three classes, those affecting (1) temperature, (2) rainfall, and (3) terrestrial magnetism. As respects the first, it has been discovered that when underground temperatures are examined, so that local and temporary causes of change are eliminated, there is a recognisable diminution of temperature in years when spots are most frequent. We owe this discovery to Professor C. P. Smyth, Astronomer Royal for Scotland. The effect is very slight; indeed, barely recognisable. I have before me, as I write, Professor Smyth's chart of the quarterly temperatures from 1837 to 1869, at depths of 3, 6, 12, and 24 French feet. Of course, the most remarkable feature even at the depth of 24 feet, is the alternate rise and fall with the seasons. But it is seen that while the range of rise and fall remains very nearly constant, the crests and troughs of the waves lie at varying levels. After long and careful scrutiny, I find myself compelled to admit that I cannot find the slightest evidence in this chart of a connection between underground temperatures and the eleven years period of sun spots. I turn, therefore, to the chart in which the annual means are given; and noting in the means at the lesser depths "confusion worse confounded" (this, of course, is no fault of Professor Smyth's, who here merely records what had actually taken place), I take the temperatures at a depth of 24 French feet. Now, neglecting minor features, I find the waves of temperature thus arranged. They go down to a little more than 46 degrees of the common thermometer in 1839-40; rise to about 47 degrees in 1847; sink to 474 degrees in 1849; mount nearly to 47 degrees again in 1852-53; are at 47 degrees in 1856-57; are nearly at 48 degrees in 1858-59; then they touch 47 degrees three times (with short periods of rising between), in 1860, 1864, and 1867; and rise above 47 degrees in 1869. Now if we remember that there were maxima of spots in 1837, 1848, 1859-60, and 1870, while there were minima in 1843, and 1855-56, I think it will be found to require a somewhat lively imagination to recognise a very striking association between the underground temperature and the sun's condition with respect to spots. If many spots imply diminution of heat, how does it come that the temperature rises to a maximum in 1859, and again in 1869? if the reverse, how is it that there is a minimum in 1860 ? I turn, lastly, to the chart in which the sun-spot waves and the temperature waves are brought into actual comparison, and I find myself utterly unable to recognise the slightest association between them. Nevertheless, I would not urge this with the desire of in any way throwing doubt upon the opinion to which Professor Smyth has been led, knowing well that the long and careful examination he has given to this subject in all its details, may have afforded ample though not obvious evidence for the conclusions at which he has arrived. I note also, that, as he points out, Mr. Stone, director of the Cape Town Observatory, and Mr. Cleveland Abbe, director of the Cincinnati Observatory, have since, "but it is believed quite independently, published similar deductions touching the earth's temperature in reference to sun-spots." All I would remark is, that the effect is very slight and very far from being obvious at a first inspection. Next as to rainfall and wind. Here, again, we have results which can hardly be regarded as striking, except in the forcible evidence they convey of the insignificance of the effects which are to be imputed to the great eleven-year spot period. We owe to Mr. Baxendell, of Manchester, the most complete series of investigations into this subject. He finds that at Oxford, during the years when sun-spots were most numerous, the amount of rainfall under west and south-west winds was greater than the amount under south and south-east winds; while the reverse was the case in years when spots were few and small. Applying corresponding processes to the meteorological records for St. Petersburg, he finds that a contrary state of things prevailed there. Next we have the evidence of the Rev. R. Main, director of the Radcliffe Observatory at Oxford, who finds that westerly winds are slightly more common when sun-spots are numerous than at other times. And lastly, Mr. Meldrum, of Mauritius, notes that years of spot-frequency are characterized on the whole by a greater number of storms and hurricanes, than years when the sun shows few spots. The association between the sun-spot period and terrestrial magnetism is of a far more marked character, though I must premise that the Astronomer Royal, after careful analysis of the Greenwich magnetic records, denies the existence of any such association whatever. There is, however, a balance of evidence in its favor. It seems very nearly demonstrated that the daily sway of the magnetic needle is greatest when sun-spots are numerous, that magnetic storms are somewhat more numerous at such times, and that auroras also are more commonly seen. Now it has been almost demonstrated by M. Marié Davy, chief of the meteorological division in the Paris Observatory, that the weather is affected in a general way by magnetic disturbances. So that we are confirmed in the opinion that indirectly, if not directly, the weather is affected to some slight degree by the great sun-spot period. Still I must point out that not one of these cases of agreement has anything like the evidence in its favor which had been found for an association between the varying distance of Jupiter and the sunspot changes. For eight consecutive maxima and minima this association has been strongly marked, and might be viewed as demonstrated,-only it chances unfortunately that for two other cases the relation is precisely reversed; and in point of fact, whereas the period now assigned to the great sun-spot wave is eleven years and rather less than one month, Jupiter's period of revolution is eleven years and about ten months, a discrepancy of nine months, which would amount up to five and a half years (or modify perfect agreement into perfect disagreement) in seven or eight cycles. But accepting the association between weather and the sun-spot changes as demonstrated (which is granting a great deal to the believers in solar weather-prediction), have we any reason to believe that by a long-continued study of the sun the great problem of foretelling the weather can be solved? This question, as I have already pointed out, must not be hastily answered. It is one of national, nay, of cosmopolitan importance. If answered in the affirmative, there is scarcely any expense which would be too great for the work suggested; but all the more careful must we be not to answer it in the affirmative, if the true answer should be negative. But it appears to me that so soon as the considerations dealt with above have been fairly taken into account, there can be no possible doubt or difficulty in replying to the question. The matter has in effect, though not in intention, been tested experimentally, and the experiments, when carried out under the most favorable conditions, have altogether failed. To show that this is so, I take the position of affairs before Schwabe began that fine series of observations which ended in the discovery of the great spot-period of eleven years. Let us suppose that at that time the question had been mooted whether it might not be possible, by a careful study of the sun, to obtain some means of predicting the weather. The argument would then have run as follows:-"The sun is the great source of light and heat; that orb is liable to changes which must in all probability affect the supply of light and heat; those changes may be periodical and so predictable; and as our weather must to some extent depend on the supply of light and heat, we may thus find a means of predicting weather changes." The inquiry might then have been undertaken, and undoubtedly the great spot-period would have been detected, and with this discovery would have come that partial power of predicting the sun's condition which we now possess, —that is, the power of saying that in such and such a year, taken as a whole, spots will be numerous or the reverse. Moreover, meteorological observations conducted simultaneously would have shown that, as the original argument supposed, the quantity of heat supplied by the sun varies to a slight degree with the varying condition of the sun. Corresponding magnetic changes would be detected; and also those partial indications of a connection between phenomena of wind and rain and the sun's condition which have been indicated above. All this would be exceedingly interesting to men of science. But, supposing all this had been obtained at the nation's expense, and the promise had been held out that the means of predicting weather would be the reward, the non-scientific tax-paying community might not improbably inquire what was the worth of these discoveries to the nation or to the world at large. Be it understood that I am not here using the cui bono argument. As a student of science, I utterly repudiate the notion that before scientific researches are undertaken, it must be shown that they will pay. But it is one thing to adopt this mean and contemptible view of scientific research, and quite another to countenance projects which are based ab initio upon the ground that they will more than repay their cost. Now, I think, if the nation made the inquiry above indicated, and under the circumstances mentioned, it would be very difficult to give a satisfactory reply. The tax-payers would say, "We have supplied so many thousands of pounds to found national observatories for the cultivation of the physics of science, and we have paid so many thousands of pounds yearly to the various students of science who have kindly given their services in the management of these observatories; let us hear what are the utilitarian results of all this outlay? We do not want to hear of scientific discoveries, but of the promised means of predicting the weather." The answer would be, "We have found that storms in the tropics are rather more numerous in some years than others, the variations having a period of eleven years; we can assert pretty confidently that auroras follow a similar law of frequency; south-west winds blow more commonly at Oxford, but less commonly elsewhere, when the sun-spots, following the eleven year period, are at a maximum; and more rain falls with south-westerly winds than with south-easterly winds at Oxford and elsewhere, but less at St. Petersburg and elsewhere, when sun-spots are most numerous, while the reverse holds when the spots are rare." I incline to think that on being further informed that these results related to averages only, and gave no means of predicting the weather for any given day, week, or month, even as respects the unimportant points here indicated, the British tax-payer would infer that he had thrown away his money. imagine that the army of observers who had gathered these notable results would be disbanded rather unceremoniously, and that for some considerable time science (as connected, at any rate, with promised "utilitarian" results) would stink in the nostrils of the nation. I But this is very far, indeed, from being all. Nay, we may almost say that this is nothing. Astronomers know the great spot period; they have even ascertained the existence of longer and shorter periods less marked in character; and they have ascertained the laws according to which other solar features besides the spots vary in their nature. It is certain that whatever remains to be discovered must be of a vastly less marked character. If then the discovery of the most striking law of solar change has led to no results having the slightest value in connection with the problem of weather-prediction, if periodic solar changes of a less marked character have been detected which have no recognisable bearing on weather changes, what can be hoped from the recognition of solar changes still more recondite in their nature? It is incredible that the complex phenomena involved in meteorological relations regarded as a whole, those phenomena which are but just discernibly affected by the great sun-spot period, should respond to changes altogether insignificant even when compared with the development and decay of a single small sun-spot. It appears to me, therefore, that it is the duty of the true lover of science to indicate the futility of the promises which have been mistakenly held out; for it cannot be to the credit of science, or ultimately to its advantage, if government assistance be obtained on false pretences for any branch of scientific research.-St. Paul's Magazine. A RUN TO VIENNA AND PESTH. IT WAS on the 30th of April, the day before the World's Exhibition opened, that I reached Vienna. When I left Scotland sixty-six hours before, the sun was bright and warm, and everything promised spring. Vienna is eight degrees of latitude, or 550 miles south of my northern home, not to speak of the twenty degrees of east longitude-and it was a bitter disappointment to find that I had left all the brightness and warmth behind me. It was raw in London; it was gusty and uncomfortable about Dover and Óstend; it was raining as the train crawled, an hour and a half late, into the capital of the Eastern Empire. Their own familiar May, laden with influenza, was in readiness, a truly delightful surprise for the English visitors. It neither surprised nor shocked the Viennese. Vi enna is very cold when it is cold, and very hot when it is hot. It rains a great deal there, it snows a little, it blows bitterly at times. To-day the sun makes the place as hot as an Italian market-place in a blazing summer. To-morrow the winds that sweep down the long trough of the Danube, or through the gaps of the encircling hills, chill one to the bone. People say that a fall of 30° Fahrenheit in the course of a day is not uncommon, and chest complaints are dangerous and abundant. Everybody who goes to see the World's Exhibition should prepare for heat and cold, and dust and rain, and mud, and, above all, sudden and violent changes of temperature. The first of May, the morning big with the fate of Baron von Schwartz Senborn and the Austrian Empire, was as depressing as it well could be. From low thick clouds a sleety drizzle dripped on the innumerable strangers who were supposed to have been gathered from all ends of the earth to witness the opening at the low charge of fifty shillings a-piece. From the Stephan's Platz, which is an apology for a square in the centre of the city, and as like a square as St. Paul's Churchyard, an interminable line of omnibuses and carriages streamed outwards over the three miles which lay between it and the Exhibition gates. Early people started at eight; those who were not to be hurried, at nine; those who were always too late for everything thought ten time enough to enable them to get to the gates at eleven. At eleven the programme said that every entrance was to be closed; the interval till noon, when the Emperor and his Imperial and Royal guests were to open the Exhibition, being sacred to the admission of officials and the great people who were not to be jostled among the meaner crowd. The programme broke down, as it was no doubt meant it should; for when eleven came, a mile or two of carriages in continuous lines still stretched on the wrong side of the gates. The envious weather deprived the Viennese of more than half the pleasures of this great People'sExhibition on the road to the real show. The open carriages were very few, and the toilettes in them were very much subdued. Broughams are disappointing to the most contented crowd, and even the hundreds of thousands who lined the road two, three, and four deep, on both sides of it, as we got into the Prater and neared the gates, would have found time hang heavy on their hands on that raw, drizzly morning but for the uniforms of all nations which went flashing past incessantly. There was the most wonderful variety and richness of costume. The Hungarian noble on a State occasion is a sight to which the imagination of untravelled Western Europe is scarcely equal, and the crowd supped full of ambassadors, and archdukes, and Hospodars, and Hungarians, and Pashas, and full-dress generals and admirals of all the armies and navies of Europe. At the end of all this there was the Emperor and Empress, and half Princes Royal and Princes Imperial, and it was content to wait. Everybody now knows the plan of the Exhibition. There is a cupola bigger than the dome of St. Paul's, under which is the great central space called the Rotunda. In the middle of this the framework of the magnificent fountain, which is to diffuse fragrance and refreshing coolness through the sultry summer, was covered, on the opening day, with evergreens. A great central space, like the saw-dust of a circus, separated it from the crowds of spectators, whose seats were in rows slanting to the inner line of pillars. Between them and the outer wall was a huge belt of floor space, meant for the crowds who could not find |