coarse and fine grits and greywacke, having red and green bands of flinty mudstone, conglomerate, and occasional breccia associated with them, occur-a persistent band of conglomerate containing quartz-rock pebbles, Lydian stone, and jasper characterise this group. The conglomerate, being locally known as "Haggis Rock," has furnished the name to the series, which is about 1,800 feet thick. The Haggis group in Dumfriesshire is seen striking across the river Afton, also, along the N.W. flanks of the Lowther hills, and elsewhere in this county. More to the north it can be recognised along the north-western margin of the Silurian area in Crawfordjohn, Lanarkshire. The Haggis rock is not persistent in its character. To the N.E. this conglomerate becomes much finer in grain, and passes "into a gritty greywacke." This group has hitherto yielded no fossils. In Wigtonshire the Haggis rock cannot be distinguished as a distinct series; its characteristic conglomerate being, as already seen, of local occurrence, it does not appear to manifest itself in the Silurians in the S.W. of Scotland. (To be continued.)

LOCAL SCIENTIFIC SOCIETIES

N very many ways has the general advance of intelligence, elevation of taste, and spread of education been shown during the present century, and more especially during the last thirty years; one of these ways is undoubtedly the increasingly rapid spread of Local Scientific Societies. What we mean by a "Local Scientific Society," as distinguished from the large Societies of London, is an association of individuals in a particular locality for the common study of one or more branches of science, by the reading of original papers, and what is perhaps of more importance, the actual investigation of the natural history-geology, zoology, botany, meteorology-and archæology of its district. Of the societies established within the last thirty years, nearly all are marked by these characteristics; such at all events is their professed object, and we are glad to say that, to judge from the special reports which we have received, and the numerous printed "Proceedings" of greater or less pretensions which are sent us from time to time, a very large proportion creditably carry out their pro

gramme.

In a number of the principal towns of England and Scotland associations exist, dating, some of them, from the end of last century, known as "Literary and Philosophical Societies," or by some similar title. These are generally comparatively wealthy, possessed of good buildings containing a library, museum, reading-rooms, lecture-hall, &c., with a large body of members belonging to the middle and upper classes. These, however, so far as their original objects are concerned, with one or two exceptions, scarcely come under the category of Local Scientific Societies, in the sense of the definition given above, though many of them, stimulated by the growing taste for Science, have recently added to their usual courses of lectures on literary subjects, others on subjects connected with Science, and have even organised classes for the study, under competent lecturers or teachers, of one or more branches of Science. In some i stances, moreover, a few of the members of these respec

table old associations have united to form societies of kind which entitle them to be regarded as Local Scient Societies, and even Field-Clubs. Still, all these o.. societies, as they existed previous to 1830. diff.in many essential respects from the Local Societies Field-Clubs which began to spring up about that tr even the well-known Literary and Philosophical Soc of Manchester, quite on a par with some of the t London Societies, and which has produced original of the highest value, has been all along confined the learned and professional men of the city and neg bourhood, who have made use of the meetings of Society for the purpose of making known the resu..: their independent scientific investigations.

So far as can be ascertained, the society just n tioned is the oldest provincial society which can considered as in any way scientific, having been esta lished in 1784, for the purpose of diffusing "literary scientific intelligence, and of promoting the literary scientific inquiries of learned men in the town and ne bourhood." "The results of its labours," Sir Wa Elliott says, in his valuable address to the Edinburg" Botanical Society, in 1870, on this subject, "were put lished in Memoirs,' the first volume of which appeara in 1785, at which time James Massey was president, a Thomas Barnes, D.D., and Thomas Henry, F.R.S, a Secretaries. Five volumes had appeared up to 18.. In 1805 a second series commenced under the RJohn Walker, President, and John Hall and Johr Dalton, Secretaries, which had extended to five volumes more in 1860. A third series was commenced in 1852, and has reached volume xiii. The second series s enriched with many papers by Dalton, including the firs development of the atomic theory." In 1858 a microscopical and natural history section was established the latter, however, we regret to say, is since defunct.

The next society of this class in order of time was inst tuted at Perth in 1781, as the Perth Literary and Antiqua.ian Society; we need not say that, so far as eminence is concerned, it was never to be compared with the Mar chester Society. It has never done scientific work of any value, though it possesses a handsome building, with a museum, devoted mostly to antiquities, but having a finc natural history collection as well, and a good library. Like many other societies of a similar kind, its building serves as a kind of meeting-place or club, where those members who have nothing to do can meet and have a gossip, and read the papers. This society has published only one volume of "Transactions" (in 1827), but so far as we know they have now no transactions to record. A few years ago, as will be seen from our list in Vol. viii. p. 521, a Natural Science Society was established in the county, with Perth as its headquarters, which gives promise of being one of the best working Local Scientific Societies in the kingdom.

In 1801 a society of a similar kind was established in the sister kingdom, the Literary Society of Belfast, which has never done anything to call for note here. Previous to this, however, in 1793, the Newcastle-on-Tyne Literary and Philosophical Society was established, which, although it has published only one volume of memoirs, and is little more than the owner of an excellent public library, does good work by providing educational courses of lectures for in

struction in mathematics, chemistry, and other branches of science as well as literature.

Up to 1830, about twenty other societies, more or less "Philosophical," which term seems then to have been thought a more dignified term than "Scientific," were instituted within the three kingdoms, including the Ashmolean Society of Oxford, and the Cambridge Philosophical Society. Of these, no less than six were in Yorkshire alone, a county, as we shall see, which continues to hold the foremost place, so far as number of scientific societies is concerned; the West Riding bristles with little Field Clubs. Among the best of the societies referred to is the Liverpool Literary and Philosophical Society, which, especially since its amalgamation in 1844 with the Natural Science Society, has done some excellent work, as can be seen from its voluminous "Proceedings," which contain papers that would do credit to any society. The Glasgow Philosophical Society is also one of high standing; and the Royal Geological Society of Cornwall, founded in 1814, which has done some good work in connection with the geology of the district. The Royal Institution of Cornwall is also one of the most creditable of these old societies, having been formed in 1818, for the advancement of knowledge of natural history, natural philosophy and antiquities, especially in their connection with Cornwall. Besides its valuable antiquarian work, it has pubished “The Cornish Fauna," a compendium of the natural history of the county.

The one of these older societies which in its object and work corresponds most nearly to our definition, is the Northumberland, Durham, and Newcastle Natural History Society, instituted at Newcastle-on-Tyne in 1829. Among its original members were Sir John and Sir Walter Trevelyan, and the late Albany Hancock, and both before and since its junction with the Tyneside Naturalists' Field Club, it has done much work of a kind similar to that which the recently established Field Clubs aim to do, having between 1831 and 1838 published two volumes containing valuable lists of the flora and fauna of Northumberland and Durham. This society, though somewhat crippled for want of funds, is still in a flourishing condition, and continues, in conjunction with the Tyneside Club, to publish in their Transactions, under the title of "Natural History Transactions of Northumberland and Durham," excellent lists of the fauna and flora, existing and fossil, of the district which it has adopted as its field for work. It possesses some splendid collections which the Newcastle College of Physical Science is generously allowed to use for purposes of study.

Had we space, others of these societies founded previous to 1830, as well as some of a more ambitious kind than the simple Field-Club, instituted since that time, could be named, which stimulated either by the example of the field-clubs, or more probably by the general advance of culture and the growing impressiveness of Science, have done much to foster a love for Science in their respective neighbourhoods and to investigate the natural history of their several districts. A large proportion of societies of this class are found in the south-west of England, in Devonshire and Cornwall: such are the Cornwall Polytechnic Society, the Devonshire and Cornwall Natural History Society, the Devonshire Association-a peripatetic Society founded in 1862 after the model of the British Association-the

Royal Institution of South Wales (Swansea), and the Isle of Wight Philosophical and Literary Society. Others also we might mention at the other end of England, for an examination of our list shows that the activity of the country in this respect has been developed to the greatest extent in the north and south.

These societies, though differing in some essential respects from the simple Field-Club, yet in their own way do good and serviceable work by the establishment of museums, the encouragement of local exhibitions, the occasional publication of papers illustrative of the natural history and archæology of the district, and recently, what we deem of considerable importance, the institution of courses of lectures by eminent men of science, and the establishment of classes for the working and other classes who are engaged during the day. We would urge all of this class of association to bestir themselves to the performance of more thorough and more extended work in these directions, thereby not only doing a benefit to the members themselves, as well as to the cause of Science, but elevating the district in which they are located, and thus helping the country onward in the general march of improvement. By means especially of continuous series of lectures by eminent men of science and by well-organised systems of classes, the good that might be done by these institutions would, we believe, be inestimable; and now that the Science and Art Department offers such splendid facilities for the establishment of classes and museums in connection with any institution that chooses to take advantage of them, no local society of any pretensions need any longer be without the material of a comprehensive and high-class education for its members and those in its neighbourhood who are willing to be improved; only a lazy unwillingness to keep up with the rapid progress of the time can deprive a neighbourhood of these advantages. The Royal Cornwall Polytechnic Society, the first " Polytechnic " in the United Kingdom, is an example of what can be done in one way, by the establishment of lectures and classes, and by the institution of medals and money prizes for successful attempts to apply Science to industry. But a model which all literary and philosophic societies, et hoc genus omne, would do well to imitate, though they would find it difficult to rival, is the Birmingham and Midland Institute, an institute of which its originators may well be proud, and for the establishment of which they deserve the gratitude of the busy and important district in the midst of which it is planted. It scarcely comes within the scope of our subject, and we only mention it to show to the class of societies with which we are at present dealing, what they might hope to achieve if they only had the will and the generosity to bestir themselves and take the necessary steps. There is no reason why in every county town or other suitable place institutions of this kind should not be established, forming active centres of intellectual culture, and to which the smaller scientific societies of the surrounding districts might be affiliated without losing their independence and with very valuable results. We hope ere long to see this accomplished; and who are better fitted to take the initiative in the matter than those societies which pretend to represent the culture of the districts from which their members are drawn?

(To be continued.)

almost impossible to carry out any scientific or literary inquiry in a complete manner, without resorting to the great national museum. There are doubtless many things which the Trustees have not done, but is it a slight matter that they have given us, on the whole, by far the most extensive and complete body of collections anywhere brought together in the world? The library and reading-room alone are enough to do honour to their management, and it is almost impossible to fathom the degree in which this library assists every kind of inquiry. When we are least aware, we are often enjoying the fruits of investigation in that library; the late Prof. Boole, for instance, spent the last few months of his life in the Museum, pursuing an exhaustive inquiry into previous writings on the subject of Differential Equations.

As regards the other collections, I presume that no one will call in question their enormous extent; and the fact that they are not adequately lodged and displayed as yet, is due to their very vastness, and to the fact that Government would not, until lately, afford the money for the new buildings. As regards the real interests of original inquiry, too, comparatively little harm is done by the want of room for exhibition, since bond file scientific students can always obtain access to the collections.

I am far from denying that the officials who have conducted the South Kensington Museum have, by an enormous expenditure of public money, collected together a great quantity of beautiful objects of art, and have thus not only afforded opportunities for art study, but have made this museum a very agreeable and fashionable lounge. But I must protest against the notion, apparently countenanced in NATURE, that the scientific value and work of a national museum is to be measured by the number of millions of persons who saunter through the galleries. No doubt the utility of a museum in affording popular instruction and elevated amusement to large masses of people is very considerable, but this popular work is altogether of a different order from the strictly scientific object of collecting together all the products of intellect and of Nature. It is an unavoidable misfortune of the best and highest work in science that it is quite unobtrusive. The public is struck by the thousands who crowd the decorated galleries of South Kensington. There is nothing to attract public attention in the two or three hundred bookworms patiently ploiding through the books in the Museum library, or the few students turning over the drawers of the zoo. logical, botanical, mineralogical, numismatic, and other collections. But in NATURE, which has so powerfully advocated the necessity of promoting original research in this country, I should expect, more than anywhere else, to find a due appreciation of the noble work which is being carried out by the British Museum trustees, and by the staff of eminent scientific and literary men who are employed under their direction in promoting almost every branch of literature and science. We have heard many complaints of the apathy displayed by Government in the promotion of science. The existence of the British Museum is the best answer to that complaint. As regards those branches of science which demand the use of large collections, it may be regarded as the great national laboratory; and if scientific men do not make adequate use of it, that is their fault and not that of the trustees. W. STANLEY JEVONS

[Our opinion of the immense importance to research of the collections of the British Museum is quite in accordance with the above letter of our esteemed correspondent, and if he will read the article again he will see nothing in it to indicate any difference of opinion. Indeed we regard the positions of the scientific men in the British Museum as positions of endowed research, and positions, moreover, which have amply justified it, miserable as the amount is in many cases. Our objection is to the existence of trustees not represented by a Minister, and to the action of the trustees, who have not expanded the area of the utility of the collections, and who have cared so little for the men of science working under them and the collections themselves that the former are underpaid and the latter are much less useful than they might be. Mr. Jevons concedes the whole point when he refers to the money so properly spent at South Kensington; for had the British Museum been under the same Minister, money would have been spent there too. The money must be spent unless we are to sink to the level of-well, let us say Morocco; and it is to prevent this that the proposed transfer has been sug gested.-ED.]

On the Équilibrium of Temperature of a Gaseous
Column subject to Gravity

IN NATURE, vol. viii. p. 486, Mr. Guthrie asks the question, "Is thre no possibility of testing the nature of thermal equili brium of a column of still air?" I think to this question an

answer may be given, which, though indirect and imperfect, will perhaps decide the controversy on the above subject.

If gravity causes in the temperature of a gaseous column the difference, which Mr. Guthrie thinks it does, that difference must be in proportion to the height of the column, and in inverse proportion to the specific heat of the gas. Hence it follows that, if two equal columns of different gases, both under the same thermal influence, are joined at their lower parts by a thermo-electric pile, the side of this pile, which is surrounded by the gas with the highest specific heat, must be constantly cooler than the other side. The result of my experiments respecting this, is the confirmation of Mr. Guthrie s opinion. The description of these experiments, and a theoretical treatise on the subject, have been in the hands of Prof. Poggendorff since the beginning of last June, and will be published in an early number of his Annalen. I hope that my experiments will induce others to try them in the same or in another manner, in order to bring the question concerning the influence of gravity on the thermal equilibrium to a final decision. Should it prove in favour of Mr. Guthrie's theory, as I believe it will, this theory, represented till now only by a very small minority, although it was broached twenty years ago by Waterston,* will give rise to results† which may perhaps clear up many of our ideas about Kosmos.

The argument which Prof. Clerk-Maxwell has brought against Mr. Guthrie in NATURE, vol. viii. p. 85, does not appear to me to be generally correct. He says:-In a given horizontal stratum of a gaseous column subject to gravity, a greater number of molecules come from below than from above to strike those in the stratum, because the density of the gas is greater below than above. Certainly the number of molecules, which enter into such a stratum during a certain time, depends upon the density of the gas, but besides this, it depends upon the proba bility of entering into it, which exists for each molecule. Now, this probability is not only dependent upon the distance of a molecule from the stratum, upon its velocity, its direction and its encounters with other molecules, but also upon the very fact of its being above or below the stratum.

Gravity continually tends to diminish the dis'ance between any horizontal stratum and each molecule which is above the stratum, and continually tends to increase the distance between the stratum and each molecule which is below. Hence it follows that the probability of entering into the stratum will be greater for a molecule which is above than for one below, if, in the case of both, all other circumstances are equal. For example, consider two molecules, which in a given moment move with the same velocity and in the same direction on the two sides of the stratum; if this direction is horizontal like the stratum, and if in the given moment the distances of the molecules from the stratum are both very small, in the next moment the molecule above the stratum will have entered into it, while that one delɔw will have removed from it.

In the case of the density being greater below the stratum than above, more molecules would enter it from below, if gravity did not exist. But under the influence of gravity, the effects of the difference in density can be balanced by those of the abovementioned difference in the probability, which exists for each molecule of entering into the stratum during a certain time. I even consider this last difference to be the dynamical cause of the difference in density.

Westend, near Berlin, Oct. 20

Periodicity of Rainfall

G. HANSEMANN

As far as my own figures are concerned, the reply to Mr. Meldrum's question is very easily afforded. I agree with him that it is undesirable to use averages deduced from groups of stations variable both in the number and locality of their components. The observations which I quoted were those of a single station, Halton, St. Philip, Barbadoes.

With respect to the general question, I regret being unable to share Mr. Meldrum's evident enthusiasm, and that a very different opinion has been published in the Zeitschrift, by Dr. Jelinek, one of the most eminent meteorologists of the present day. It may be convenient to some readers to be informed that an abstract of Dr. Jelinek's article is given in "British Rainfall, 1872," together with a general résumé of the state of the question up to the date of its publication. Camden Square, Nov. 1

* In "On Dynamical Sequences of Kosmos."

G. J. SYMONS

+ I have expounded some of these results in an abstract mechanical form in "Die Atome und ihre Bewegungen" (Coln Lengfeld'sche Buchhandlung, 1871).