On Wet- and Dry-bulb Formule. By Prof. J. D. EVERETT, F.R.S.E. The author said August, Apjohn, and Regnault have investigated formulæ for determining the dew-point, by calculation, from the temperatures of the dry- and wet-bulb thermometers; but Regnault's experiments on the specific heat of air were not performed till a later date, and all these authors have adopted, in their investigations, the value obtained by Delaroche and Berard, which is 267, whereas the correct value is 237. But when this correct value is introduced into Regnault's formula, the discrepancies which he found to exist between calculation and observation are increased, and amount, on an average, to about 25 per cent. of the difference between wet-bulb temperature and dew-point. August and Apjohn erred in assuming that all the air which gives heat to the wet bulb (1) falls to the temperature of the wet bulb, and (2) becomes saturated. These two false assumptions would jointly produce no error in the result, if the depressions of temperature in the different portions of air affected were exactly proportional to their increments of vapour-tension, and if some of the air were saturated at the temperature of the wet bulb. But it is probable that, when there is little or no wind, the mass of air which falls sensibly in temperature is larger than that which receives a sensible accession of vapour, and that, in high wind, the supposition that some of the air has fallen to the temperature of the wet bulb is more nearly fulfilled than the supposition that it has taken up enough vapour to saturate it. The effect of radiation, which is ignored in the formulæ, tends in the same direction as these two inequalities, and all three are roughly compensated by attributing to air a greater specific heat than it actually has. The discrepancies above referred to are thus explained. On the General Circulation and Distribution of the Atmosphere. The object of this paper was to call the attention of meteorologists to a theory which is jointly due to Prof. James Thomson of Belfast, and Mr. Ferrel of Boston, U.S.A., and which gives the only satisfactory account of the grand currents of the atmosphere, and of the distribution of barometric pressure over the earth's surface, the irregularities arising from the distribution of land and water being neglected. Independent proofs were also given of some of Mr. Ferrel's results. In virtue of the earth's rotation, with angular velocity ∞, a body, in latitude A, moving along the earth's surface with relative linear velocity v, tends to describe on the earth's surface a curve concave to the body's right in the northern and to its left in the southern hemisphere, the radius of cuvature of the concavity being 6850 v feet, if the velocity is in feet per second. The deflection from a parallel of latitude into a great circle is usually negligible in comparison, being represented by the curvature of a circle of radius R cotan λ, where R is the earth's radius. sin A To keep the moving body in a great circle, or in a parallel of latitude, requires a constraining force per unit of mass equal to 2 w sinλ. v, which if the foot and second be units, is 6850; and this formula applies alike to all horizontal directions of motion. v sin λ The air over the extra-tropical parts of the earth has, upon the whole, a relative motion towards the east, and therefore presses towards the tropics with a force which can be computed by the above formula, if the eastward velocity at each parallel is known. If v denote this velocity at any parallel, in feet per second, the increase of pressure per degree of latitude at that parallel is 0019 v sin λ inches of mercury. This is sufficient to account for the observed increase of pressure from the poles to the tropics, which may be roughly stated at 01 inch per degree. Between the tropics, the general movement of the air, relative to the earth, is towards the west, and the increase of pressure is therefore from the equator towards the tropics. If any stratum of air have less than the average eastward or westward velocity (relative to the earth) which prevails through the strata above it, it will not be able to resist the differential pressure from or towards the equator which their motion produces. For this reason, the lowest stratum of air, having its velocity relative to the earth kept down by friction, generally moves from the tropical belts of high barometer to the regions of low barometer at the poles and equator. This is the origin of our S. W. winds, and of the prevalent N.W. winds of the Southern oceans, which must be regarded as constituting an undercurrent towards the pole, beneath a topmost current, also towards the pole, and a middle return current. Between the tropics, on the other hand, the motion thus generated in the lowest stratum of air coincides with the motion due to difference of temperature, and this is probably the reason why the trade-winds are more constant than the winds of the temperate zones. Excess of temperature and moisture in the equatorial regions is unquestionably the prime mover of the winds, as has long been believed; but the crossing of the winds at the tropic, which has often been coupled with it, is a physical impossibility. The tendency of a moving mass of air to swerve to its own right in the northern hemisphere explains the well-established law (Buys Ballot's), that the wind, instead of blowing at right angles to the isobaric lines, and so running down the steepest gradient, usually makes an angle of only 20° or 30° with these lines, keeping the region of lower barometer on its left. The rotation of cyclones is an example of this law; and the pressure which the spirally inflowing streams exert to their own right in virtue of the earth's rotation is the main cause of the excessive central depression. Reference was made to Prof. J. Thomson's paper in the British Association Report for 1857, and to papers by Mr. Ferrel in the American Mathematical Monthly for 1860, and in 'Nature,' July 20, 1871. Observations Physiques en Ballon. By M. JANSSEN. The Influence of the Moon on the Rainfall. By W. PENGELLY, F.R.S. &c. The author commenced by stating that though many of the popular beliefs respecting "The Moon and the Weather were no doubt utterly untenable, Sir J. Herschel and M. Arago concurred in the opinion that, on the whole, the rainfall was somewhat below the general average about the time of full moon, and that the fact was ascribable to the effect of the solar heat absorbed by the moon and radiated by her to us. He then proceeded to show that the heat thus received by us must be greatest when, or very soon after, the moon was full, when she was in perigee, and (in the northern hemisphere) when she had north declination; that the effect of this heat would be a diminution of the rainfall, not during the lunation as a whole, but during a certain portion of it, and therefore an augmentation during some other period; that the effect would be variable and never considerable; and that in the northern hemisphere it would be a maximum when the moon was, at one and the same time, full, in perigee, and in her highest north declination. The paper was illustrated with several tables and diagrams based on rainfall observations made at Torquay during eighty-seven complete lunations ending with January 19, 1871. The following were amongst the conclusions with which the paper closed:No indication of the moon's influence on the rainfall can be detected in the data furnished by an isolated lunation, or by even a few successive lunations. Though it may be doubted whether the rainfall statistics of a period shorter than that in which the moon's nodes complete a revolution, or of a solitary locality, would justify general inferences, the data under discussion appear to indicate that, in the long run, the moon does somewhat influence the rainfall; that on the average the dry period of a lunation extends from the first day before full moon to the first day before the third quarter, and the wet period from the day of the first quarter to the second day before the full moon; that the moon's influence on the number of wet days is less marked; and that the rainfalls are, on the whole, rather least heavy when the moon has north declination, and when she is in perigee—all indications harmonizing well with physical considerations. On the Inferences drawn by Drs. Magnus and Tyndall from their Experiments on the Radiant Properties of Vapour. By R. RUSSELL. The author agreed in the main with Tyndall's deductions. He endeavoured to show that vapour of water had no power of transmitting its radiant heat into space. This proposition was supported by arguments from various natural phenomena, On Parhelia, or Mock Suns, observed in Ireland. By WILLIAM A. TRAILL, of the Geological Survey of Ireland. The author began by stating that the above phenomena were analogous to the paraselenæ or mock moons, and though of not unfrequent occurence in northern latitudes, were in these countries of great rarity. The phenomena observed by him were seen on the 28th of January, 1869, near the village of Strangford (Co. Down), lat. 54° 21', long. 5° 35', west of Greenwich, and first appeared as three brilliant suns situated in the same horizontal line, about 15° to 20° above the horizon, and of equal brightness. The two outer, or mock suns, gradually assumed the prismatic colours, and lengthening out joined above, thus forming the "ordinary halo," in which the red colour was nearest to the real sun. Concentric and exterior to it was another prismatic halo, the "extraordinary halo," which was rather fainter, in which also the red colour was innermost. Touching this latter externally was the "circumzenithal halo," which was by far the most brilliant of the three, lying as if horizontally overhead. In this likewise the red colour was next the sun, thus forming the outer periphery of the halo. The phenomena began a little after 2 P.M., and lasted only for about half an hour, attaining its greatest splendour at 2h 20m P.M. Throughout the duration of the phenomena the sky was of a clear blue colour, and almost unobscured; a few light fleecy clouds were, however, drifting northward, slight "cirrus" clouds stretched across part of the sky, from E. to W., and throughout the whole time the points where the mock suns had first appeared continued the brightest. With regard to the state of the weather at the time, the day was mild and fine, no rain falling till the evening. The sun was warm, but a cold southerly wind prevailed. The moon was full on the previous day, and exceptionally high springtides occurred along the N.E. portion of the Irish coast. The barometer fell rapidly 7 inch within twelve hours. The wind veered round gradually through 140°, and increased in velocity from 6 to 38 miles an hour, the thermometer ranging from 42° to 46°, and towards evening the rain descended in torrents. The succeeding ten days or fortnight was characterized by excessively bad weather, rain, and storms. The author lastly touched on the different theories by which these phenomena could be most easily accounted for. THE PROGRESS OF SCIENCE. Government Action on Scientific Questions By Lieut.-Col. A. STRANGE, F.R.S., F.R.A.S. The author called attention to the number, variety, and importance of those national duties, involving Science, which can be performed by the Executive Government alone. He pointed out that the English Government possesses as yet no provision for regulating the performance of these duties in a systematic manner. He maintained that the requisite provision must consist of two additions to the existing administration, neither of which, however, unaccompanied by the other would suffice-namely, first, a Minister of Science; and, second, * From Observations at the Armagh Observatory. TRANSACTIONS OF THE SECTIONS. UNIVERSITY a permanent Consultative Council, to advise the various departments through the Minister. His purpose was not to endeavour to uproot the existing system, but to graft upon it additions demanded by experience and the progress of knowledge. Assuming that the Minister would be appointed for his station, parliamentary ability, and political influence, he would need advisers, who should be a permanent, well-paid, and therefore a responsible Council of Science, representing all the main branches of science, the different arms of the military and naval services, commerce, agriculture, and the engineering profession. The Council should be quite independent of political influences. The author described the mode of election to the Council which he proposed, and in which he would give a certain voice to the Scientific Societies. The duties of the Council would befirst, to advise the Government on all questions arising in the ordinary routine of administration submitted to it by the various departments; second, to advise the Government on special questions, such as the founding of new scientific institutions and the modification or abolition of old ones, the sanctioning of scientific expeditions and applications for grants for scientific purposes; third, to consider and decide upon inventions tendered to Government for the use of the State; and, fourth, to conduct or superintend the experiments necessary to enable it to perform these duties. This would not entirely relieve the Government of all responsibility in scientific matters. The advantages to the nation accruing from a sound and comprehensive administration of science were incalculable. The author referred, for fuller particulars regarding the subject, to his paper "On the Necessity for a Permanent Commission on State Scientific Questions," read before the Royal United Service Institution on the 15th of May last, and published in No. 64 of the Journal of the Institution. Obstacles to Science-Teaching in Schools. By the Rev. W. TUCKWELL. After describing the slow progress made in scientific teaching since the Report of the Public Schools' Commission in 1864, and declaring that the first-class English schools teaching science systematically at the present momentcan be counted on the fingers of one hand, the author proceeded to show that the head masters were not altogether to be blamed for this state of things. They have inherited an order of tuition some hundred years old, fortified with minute, unbroken venerable traditions, looked upon for ages past as the supreme instrument and test of intellectual power, whole and complete in itself, supported by immense experience, worked by tried machinery. Into the midst of this wellmapped, well-proved system is thrust a strange and foreign subject, comprising many branches, and demanding multifold appliances, whose value as a mental weapon they have had no means of testing; they are called upon to surrender to this a portion of the time which already seems too short for other work, and to inaugurate a department of school labour over which they can exercise no sort of supervision or control. They ask for guidance in the new arrangements which they are called upon to form; whether any one department is educationally fundamental to the rest; whether sciences of experiment should precede or follow those of observation; what portions of the old course are to be abandoned; how far the Universities, which in many cases stamp the practical value of their work, will recognize such abandonment. They look round for accredited teachers and approved text-books, for enlightenment as to the amount of apparatus and its cost, for details of teaching and of testing, and they look in vain. They must fall back upon their own moral consciousness, for no help is tendered to them from without. I place this helplessness of head masters first on the list of obstacles which we have to chronicle; and I plead, for the moment, in their behalf, almost more than in behalf of science. For their attitude is frank and cordial; they are prepared as a body to meet the demands of the scientific public loyally and with all their might. If those who are pressing modern subjects on them will entertain their just appeal and try to understand their difficulties, they will prove the best auxiliaries science can hope to gain; for they will bring to this new department of their work the same energy and wisdom, the same self-sacrificing impartial zeal, which have already won for them the deserved esteem of the community; but if we fail to work in harmony with them, their want of sympathy and interest will be simply fatal to our schemes. Next to this helplessness of head masters came the difficulty of obtaining properly trained and certificated science-teachers. With the admirable German system, comprising special examination of Candidates for Masterships, not only in knowledge, but in teaching power, together with a year of trial in some large school before entering on their work, was compared the insufficient test offered by the English University Degree, a high test, no doubt, of intelligence and knowledge, but not of power to communicate knowledge or to infuse intelligence. Third in rank amongst the obstacles to be surmounted was placed the cost of paying science masters; and the School Commissioners, now redistributing the endowments of the country, were urged to set apart funds for science-teaching in every large school, and to insist on their being faithfully expended for the purpose. The necessity of having good teachers was then dwelt on. The first condition of success in scientific, as of other teaching, is obviously the teacher. He must be a man thorough in his special knowledge, and, if his special knowledge is to be well balanced in reference to other subjects, of the widest general culture. He must not spend all his time in teaching, but must have leisure to prepare lessons and experiments. He must possess the delicate art of handling many pupils, the force of manner which attracts them, the enthusiasm which puts and keeps them en rapport with him, the insight which reads their minds, the tact which can preserve discipline without checking inquiry, and, possessing all this and more, he must be well and highly paid. An exact estimate was offered of the cost of apparatus; and the value of workshops, museums, and other accessories of the kind was dwelt upon. After glancing at the action of the universities, the author touched on a grave item in the catalogue of difficulties. Granting that scientific teaching is essential to a perfect education, the anxious question meets us-How is it to be inserted in the curriculum of an established school? We are told that, to meet the demands of University competition, the highest pressure is already put upon the time and brains of boys; and that if four hours a week are to be accepted as the minimum demand of science, classical work must suffer. And, in order to solve this problem, some well-known schools have instituted a system of bifurcation, to which the author was opposed. If linguistic training is bad without the rationalizing aid of scientific study, no less is exclusive science bad when divorced from the refining society of literature and philology; and an admission that certain institutions stunt particular faculties is oddly followed by a device which causes each to work unchecked. The difficulty must be met fairly, and on premises which scholars as well as savans can understand. It must be met by asking whether in purely classical schools no time is wasted; why it is that in the lower forms a boy takes years to master what a clever tutor teaches in a few months at home; why the weapon of analysis, which opens every other chamber of human knowledge, should be discarded in the case of scholarship alone; whether unattractiveness is an inherent vice in Greek and Latin only, or whether, if judicious method wakens pleasure and keeps alive attention, that of itself is not economy of time; whether, lastly, the day has not arrived when Greek and Latin verse-making may not be allowed to disappear. After having written some thousand Greek and Latin verses in his own school-days, the author pronounced them waste of time, and protested against them altogether. Their elimination from our school system will be clear gain in itself, and will set free at once a much larger amount of time than is demanded for the prosecution of natural science. After enumerating at some length the details essential to the giving a fair place to science in education, the paper ended as follows:-"The summary of what I have to say is this, that our schools, in their readiness to establish science, must be aided from without. All questions of funds, of apparatus, of teachers, of selected text-books, of coordinated subjects, of University influence, and of united action come to the same point at last. We must have central leadership, at once commanding and intelligent, if the introduction of science into our schools is to be simultaneous and effective. The question has passed out of the realm of general |