or promised by twenty Fellows of the Society, and I need hardly add that the remaining £2,000 was contributed very shortly afterwards. At a subsequent meeting of the Council it was resolved :—

1. That the sums referred to as the Publication Fund, as well as those received or that may be hereafter received, for the purpose of relieving future ordinary Fellows from the Entrance Fee, and for reducing their Annual Contribution, be formed into one fund.

2. That the Entrance Fee for ordinary Fellows be henceforth abolished; and that the Annual Contribution for ordinary Fellows hereafter elected be £3 (three pounds). Also, that the income of the Fund above-mentioned be applied, so far as is requisite, to make up the loss to the Society arising from these remissions and reductions.

3. That the account of this Fund be kept separate; and that the annual surplus of income, after providing for the remission and reduction above recommended, be re-invested, until the income from the Fund reaches £600. So soon as the annual income reaches this amount, any surplus of income in any year, after providing for the remission and reduction above-mentioned, shall be available, in the first instance, in aid of publication and for the promotion of research.

A list of subscribers to this Fund will be placed in the hands of every Fellow, with the information that it will be kept open for future contributions, in the interests of research and of the Society's publications. I hope that it will be largely and speedily augmented, and that it may eventually reach an amount which will provide us with the means of accomplishing as much as is effected by the Government Fund, upon our own sole and undivided responsibility. I must not conclude my notice of this movement without a mention of those whose encouragement and liberality have most largely promoted it; and first of all, Mr. Spottiswoode, to whose counsel and active co-operation throughout, its success is mainly due; Messrs. Young's and Jodrell's contributions have already been mentioned, they have been supported by others -£2,000 from Sir Joseph Whitworth, £1,000 from Sir W. Armstrong, and £500 each from His Grace the Duke of Devonshire, Mr. De La Rue, Mr. Spottiswoode and Mr. Eyre (jointly), Dr. Siemens, and the Earl of Derby, and £250 from Dr. Gladstone. The balance comprises contributions by thirty-two Fellows.

I have to mention your obligations to Dr. W. Farr for the labour he has bestowed in ascertaining those vital and other statistics of the Society, upon an accurate knowledge of which the calculations for the reduction of fees had to be based; and to Mr. Bramwell for constructing a table showing to what extent these changes will affect the

Society's present and future income. It may interest you to know that the contribution of ordinary Fellows in future to be elected, is but little over that which was required of all Fellows from the very commencement of the Society's existence till 1823, namely, 1s. per week, and that the last Fellows who paid that sum died in 1869.

Looking back over the five years during which I have occupied this chair, I recognise advances in scientific discovery and research at home and abroad far greater than any previous semi-decade can show. I do not here allude to such inventions as the Telephone, Phonograph, and Microphone, wonderful as they are, and promising immediate results of great importance to the community; nor even to those outcomes of high attainments, the Harmonic Analyser of Sir W. Thomson, and the Bathometer and Gravitation Meter of Siemens; but to those discoveries and advances which appeal to the seeker of knowledge for its own sake, whether as developing principles, suggesting new fields of research, or awakening attention to hitherto unseen or unrecognised, or unexplained phenomena of nature, and of which the Radiometer and Otheoscope of Crookes are conspicuous examples.

In the foremost rank as regards the magnitude of the undertakings and the combination of means to carry them out, nothing in the history of physical science can compare with the Transit of Venus Expeditions. To observe the Transit of Venus various nations of Europe and the United States competed as to the completeness of the Expeditions they severally equipped. The value* of the solar parallax cannot be ascertained until the results of all the Expeditions are taken into account, when it will have an international claim to acceptance. But advances in this direction will not have ended here, the very difficulties attending the observation of the Transit of Venus, having directed attention to the method originally suggested by the Astronomer Royal in 1857, of obtaining the solar parallax from the diurnal parallax of Mars at its opposition.

Mr. Gill by the skilful employment at Ascension Island of the heliometer lent by Lord Lindsay, has greatly increased the accuracy of the method by which the necessary star comparisons with Mars are made, and there is every reason to believe that the results of his observations which are now in course of reduction will be very satisfactory.

Within the last two years a remarkable addition has been made to

The Astronomer Royal informs me that Captain Tupman, who has taken the principal share in the superintendence of the calculation, fixes provisionally on a mean parallax of 8"-8455, corresponding to a distance of 92,400,000 British miles, but that the observations would be fairly satisfied by any parallax between 8" 82 and 888, which in distance produces a range of from 92,044,000 and 92,770,000 miles, differing by 726,000 miles, a quantity almost equal to the sun's diameter.

the number of members of the solar system by Professor Asaph Hall's discovery of the satellites of Mars; and more recently, Professor Watson has announced his detection of planetary bodies within the orbit of Mercury, during the Solar Eclipse which was visible in America.

In 1876 Schmidt recorded an outburst of light in a star in Cygnus, which showed a continuous spectrum containing bright lines similar to those of the remarkable star of 1866. As the star waned the continuous spectrum and bright lines faded, all but one bright line in the green, giving the object the spectroscopic appearance of a small gaseous nebula.

Great progress has been made during the last five years at Greenwich in the method of determining the motions of the heavenly bodies by the displacement of the lines in their spectra, as first successfully accomplished by Mr. Huggins in 1868. Not only do the results obtained by the stars observed at Greenwich agree with those of Mr. Huggins, as satisfactorily as can be expected in so delicate an investigation, but the motions of seventeen more have been determined; while the trustworthiness of the method has been shown by the agreement of the values for the rotation of the sun and the motions of Venus, with the known movements of these bodies. Mr. Huggins has also obtained photographs of the spectra of some of the brighter stars, which give well defined lines in the violet and ultraviolet parts of the spectrum. These spectra have already shown alterations in the lines common to them and the sun, which are of much interest.

In Solar Physics, which afford remarkable evidence of Mr. Lockyer's energetic labours in this country and Mr. Janssen's in France, I must mention our Foreign Member's wonderful photographs of the sun, wherein the minutest of the constant changes in the granulations exhibited on its surface (and which vary in size from of a second to 3 or 4 seconds) can be studied in future from hour to hour and day to day; as can also their different behaviour at different periods of the occurrence of sun-spots.

Before dismissing this fruitful field of research, I must allude to Mr. Lockyer's discovery of carbon in the sun; and to his announced but not yet published observations on the changes and modifications of spectra under different conditions, some of which he even regards as indicating the breaking up of the atoms of bodies hitherto regarded as elementary.

Some important investigations on the Electric Discharge have been communicated to the Society by Messrs. De La Rue and Müller, and by Mr. Spottiswoode. These, prosecuted by different means, tend to limit the possible causes of the stratification observed in discharges through vacuum tubes. They also point to the conclusion that this

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phenomenon is in a great measure due to motions among the molecules of the residual gas, which themselves become vehicles for the transmission of Electricity through the tube. It is well known that gases at atmospheric pressure offer great resistance to the passage of Electricity; and that this resistance diminishes (to a certain limit, different for different gases) with the pressure. And the researches in question appear to show that the discharge, manifestly disruptive at the higher pressures, is really also disruptive even at pressures when stratification takes place. The period of these discontinuous discharges has not yet been the subject of measurement, but it must, in any case, be extremely rapid.

The remarkable experiments which have resulted in the liquefaction of the gases hitherto regarded as permanent will be noticed presently when I deliver to their authors the medals they so richly deserve.

Under the auspices of the Elder Brethren of the Trinity House, and as their scientific adviser, Professor Tyndall has conducted an investigation on the acoustic properties of the atmosphere. The instruments employed included steam whistles, trumpets, steam syrens, and guns. The propagation of sound through fog was proved to depend not upon the suspended aqueous particles, but upon the condition of the sustaining air. And as air of great homogeneity is the usual associate of fog, such a medium is often astonishingly transparent to sound. Hail, rain, snow, and ordinary misty weather, were also proved to offer no sensible obstruction to the passage of sound. Every phenomenon observed upon the large scale was afterwards reproduced experimentally. Clouds, fumes, and artificial showers of rain, hail, and snow were proved quite ineffectual to stop the sound, so long as the air was homogeneous, while the introduction of a couple of burners into a space filled with acoustically transparent air soon rendered it impervious to the waves of sound. As long as the continuity of the air in their interstices was preserved, the sound-waves passed freely through silk, flannel, green baize, even through masses of hard felt half an inch in thickness, the same sound-waves being intercepted by goldbeater's skin. A cambric handkerchief which, when dry, offered no impediment to their passage, when dipped into water became an impassable barrier to the sound-waves.

Echoes of extraordinary intensity were sent back from nonhomogeneous transparent air; while similar echoes were afterwards obtained from the air of the laboratory, rendered non-homogeneous by artificial means. Detached masses of non-homogeneous air often drift through the atmosphere, as clouds pass over the face of the sky. This has been proved by the fluctuations observed with bells having their clappers adjusted mechanically, so as to give a uniform stroke. The fluctuations occur only on certain days; they occur when care has been taken to perfectly damp the bell between every two suc

ceeding strokes; and they also occur when the direction of the sound is at right angles to that of the wind. Numerous observations were also made on the influence of the wind, the results obtained by previous observers being thereby confirmed. From his own observations, as well as from the antecedent ones of Mr. Alexander Beazeley and Professor Osborne Reynolds, Professor Tyndall concludes that the explanation of this phenomenon given by Professor Stokes is the true one.

Turning now to biological branches of Science, I find that the discoveries and researches of the past five years in this department also are far in advance of those of any previous period of equal length. The "Challenger" Expedition was, in point of the magnitude of the undertaking and completeness of its equipment, the rival of that for observing the Transit of Venus. Its general results, as far as hitherto made known, have been dwelt upon in my previous addresses, and the publication of them in detail is being rapidly pushed forward. Some very important papers by Mr. Moseley on the Corals collected on the voyage have indeed been published in our "Transactions" with admirable illustrations by himself.

To the Botanist and Geologist no subject has a greater interest than that of the conditions under which the successive Floras, which inhabited the polar area, existed and were successively dispersed over lower latitudes previous to their extinction, some in toto and over the whole globe, while others, though extinct in the regions where they once flourished, exist now only in lower latitudes under identical or under representative forms. It is only during the last few years that, thanks to the labours of those engaged in systematic Botany in tracing accurately the directions of migrations of existing genera and species, and in determining the affinities of the extinct ones, and of Paleontologists in referring the latter to their respective geological horizons, that any material advance has been made towards a knowledge of the origin and distribution of earlier and later Floras. I cannot better illustrate the condition of this inquiry than by calling your attention to two publications on the subject, which have appeared within the last few months.

As a contribution to the principles of Geographical Botany, Count Gaston de Saporta's essay, entitled "L'Ancienne Végétation Polaire (which appeared in the "Comptes Rendus" of the French International Geographical Congress) is a very suggestive one, and having regard especially to its author's eminence as a geologist and palæontologist, is sure to command attentive study. Although it may be argued that neither is solar nor terrestrial physics, nor Geology, nor Palæontology in a sufficiently advanced condition to warrant the acceptation as fully established truths of all the conclusions therein advanced, still the array of facts adduced in evidence of these conclusions is very im