to ascertain if the stream of radiant matter from the negative | parallel streams of radiant matter exert mutual repulsion, acting pole also carries a current. Here (Fig. 18) is an apparatus which not like current carriers, but merely as similarly electrified. will decide the question at once. The tube contains two negative bodies. terminals (a, b) close together at one end, and one positive terminal (c) at the other. This enables me to send two streams of radiant matter side by side along the phosphorescent screenor by disconnecting one negative pole, only one stream. If the streams of radiant matter carry an electric current they will act like two parallel conducting wires and attract one a another; but if they are simply built up of negatively electrified molecules they will repel each other. I will first connect the upper negative pole (a) with the coil, and you see the ray shooting along the line d, f. I now bring the lower negative pole (6) into play, and another line (e, h) darts along the screen. But notice the way the first line behaves; it jumps up from its first position, df, to dg, showing that it is repelled, and if time permitted I could show you that the lower ray is also deflected from its normal direction: therefore the two FIG. 19. Radiant Matter produces Heat when its Motion is arrested During these experiments another property of radiant matter has made itself evident, although I have not yet drawn attention to it. The glass gets very warm where the green phosphorescence is strongest. The molecular focus on the tube, which we saw earlier in the evening (Fig. 8) is intensely hot, and I have prepared an apparatus by which this heat at the focus can be rendered apparent to all present. I have here a small tube (Fig. 19, a) with a cup-shaped negative pole. This cup projects the rays to a focus in the middle of the tube. At the side of the tube is a small electromagnet, which I can set in action by touching a key, and the focus is then drawn to the side of the glass tube (Fig. 19, ¿). To show the first action of the heat I have coated the tube with wax. I will put the apparatus in front of the electric lantern (Fig. 20, d), and throw a magnified image of the tube on the screen. The coil is now at work, and the focus of molecular rays is projected along the tube. I turn the magnetism on, and draw the focus to the side of the glass. The first thing you see is a small circular patch melted in the coating of wax. The glass soon begins to disintegrate, and cracks are shooting starwise from the centre of heat. The glass is softening. Now the atmospheric pressure forces it in, and now it melts. A hole (e) is perforated in the middle, the air ru: hes in, and the experiment is at an end. I can render this focal heat more evident if I allow it to play on a piece of metal. The bulb (Fig. 21) is furnished with a negative pole in the form of a cup (a). The rays will therefore be projected to a focus on a piece of iridio-platinum (6) supported in the centre of the bulb. I first turn on the induction coil slightly, so as not to bring out its full power. The focus is now playing on the metal, raising it to a white heat. I bring a small magnet near, and you see I can deflect the focus of heat just as I did the luminous focus in the other tube. By shifting the magnet I can drive the focus up and down, or draw it completely away from the metal, and leave it non-luminous. I withdraw the magnet, and let the molecules have full play again; the metal is now white hot. I increase FIG. 21. the intensity of the spark. The iridio-platinum glows with almost insupportable brilliancy, and at last melts. The Chemistry of Radiant Matter importance to the presence of Matter, when I have taken extraordinary pains to remove as much matter as possible from these bulbs and these tubes, and have succeeded so far as to leave only about the one-millionth of an atmosphere in them. At its ordinary pressure the atmosphere is not very dense, and its recognition as a constituent of the world of matter is quite a modern notion. It would seem that when divided by a million, so little matter will necessarily be left that we may justifiably neglect the trifling residue and apply the term vacuum to space from which the air has been so nearly removed. To do so, however, would be a great error, attributable to our limited faculties being unable to grasp high numbers. It is generally taken for granted that when a number is divided by a million the quotient must necessarily be small, whereas it may happen that the original number is so large that its division by a million seems to make little impression on it. According to the best authorities, a bulb of the size of the one before you (13'5 centimetres in diameter) contains more than 1,000,000,000,000,000,000,000,000 (a quadrillion) molecules. Now, when exhausted to a millionth of an atmosphere we shall still have a trillion molecules left in the bulb-a number quite sufficient to justify me in speaking of the residue as matter. To suggest some idea of this vast number I take the exhausted bulb, and perforate it by a spark from the induction coil. The spark produces a hole of microscopical fineness, yet sufficient to allow molecules to penetrate and to destroy the vacuum. The inrush of air impinges against the vanes, and sets them rotating after the manner of a windmill. Let us suppose the molecules to be of such a size that at every second of time a hundred millions could enter. How long, think you, would it take for this small vessel to get full of air? An hour? A day? A year? A century? Nay, almost an eternity! A time so enormous that imagination itself cannot grasp the reality. Supposing this exhausted glass bulb, indued with indestructibility, had been pierced at the birth of the solar system; supposing it to have been present when the earth was without form and void; supposing it to have borne witness to all the stupendous changes evolved during the full cycles of geologic time, to have seen the first living creature appear, and the last man disappear; supposing it to survive until the fulfilment of the mathematician's prediction that the sun, the source of energy, four million centuries from its formation, will ultimately become a burnt-out cinder; supposing all this-at the rate of filling I have just described, 100 million molecules a second-this little bulb even then would scarcely have admitted its full quadrillion of molecules.2 But what will you say if I tell you that all these molecules, this quadrillion of molecules, will enter through the microscopic hole before you leave this room? The hole being unaltered in size, the number of molecules undiminished, this apparent paradox can only be explained by again supposing the size of the molecules to be diminished almost infinitely-so that instead of entering at the rate of 100 millions every second, they troop in at a rate of something like 300 trillions a second. I have done the sum, but figures when they mount so high cease to have any meaning, and such calculations are as futile as trying to count the drops in the ocean. In studying this fourth state of matter we seem at length to have within our grasp and obedient to our control the little indivisible particles which with good warrant are supposed to constitute the physical basis of the universe. We have seen that in some of its properties radiant matter is as material as this table, whilst in other properties it almost assumes the character of radiant energy. We have actually touched the borderland where matter and force seem to merge into one another, the shadowy realm between Known and Unknown which for me has always The possible duration of the sun from formation to extinction has been variously estimated by different authorities, at from 18 million years to 4co million years. For the purpose of this illustration I have taken the highest As might be expected, the chemical distinctions between one kind of radiant matter and another at these high exhaustions are difficult to recognise. The physical properties I have been elucidating seem to be common to all matter at this low density. Whether the gas originally under experiment be hydrogen, carbonic acid, or atmospheric air, the phenomena of phosphorescence, shadows, magnetic deflection, &c., are identical, only they commence at different pressures. Other facts, however, show that at this low density the molecules retain their chemical characteristics. Thus by introducing into the tubes appropriate absorbents of residual gas, I can see that chemical attraction goes on long after the attenuation has reached the best stage for showing the phenomena now under illustration, and I am able by this means 2 According to Mr. Johnstone Stoney (Phil. Mag., vol. 36, p. 141), I c.c. of to carry the exhaustion to much higher degrees that I can get by air contains about 1,000,000,000,000,000,000,000 molecules. Therefore a bulb mere pumping. Working with aqueous vapour I can use phos- 13'5 centims. diameter contains 13'53x0 5236 x 1.000,000,000,000,000,000,000 phoric anhydride as an absorbent; with carbonic acid, potash; 1,288,252,350,000,000,000,000,000 molecules of air at the ordinary pressure. Therefore the bulb when exhausted to the millionth of an atmosphere, contains with hydrogen, palladium; and with oxygen, carbon, and then 1,288,252,350,000,000,000 molecules. leaving 1,288,251,061,747,650.000,000.000 potash. The highest vacuum I have yet succeeded in obtaining molecules to enter through the perforation. At the rate of 100,000,000 mcle. has been the 1-20,000,000th of an atmosphere, a degree which cules a second, the time required for them all to enter will be may be better understood if I say that it corresponds to about the hundredth of an inch in a barometric column three miles high. It may be objected that it is hardly con-istent to attach primary estimate. or : 12,882.510,617,476,500 seconds, or 149,103.132.147 days, or 408,501,731 years. had peculiar temptations. I venture to think that the greatest scientific problems of the future will find their solution in this Border Land, and even beyond; here, it seems to me, lie Ultimate Realities, subtle, far-reaching, wonderful. "Yet all these were, when no Man did them know, THE BRITISH ASSOCIATION GENERAL satisfaction is expressed with the Sheffield meeting. The people of the town and district did their best, amid many difficulties, to give the members of the Association a hearty reception, and they succeeded. The excursions on Thursday were well attended, and those who took part in them seem to have enjoyed themselves. At the meeting of the General Committee, Swansea was selected as next year's place of meeting, with Prof. A. R. Ramsay as president; the date of meeting is August 25. A letter was read from the Archbishop of York, warmly urging upon the Association to meet in the archiepiscopal City in 1881, when, for some unaccountable reason, the jubilee is to be celebrated, as we have already said, in the fifty-first year of the Association's existence. As the result of the important discussion in Section F on science teaching in schools, a committee was appointed for the purpose of reporting, in addition to other matters, whether it is important that her Majesty's inspectors of elementary schools should be appointed with reference to their ability for examining on scientific specific subjects of the code, the committee to consist of Mr. Mundella, M.P., Mr. Shaw, Mr. Bourne, Mr. Jas. Heywood, Mr. Wilkinson, and Dr. J. H. Gladstone. REPORTS Report of the Committee on Erratic Blocks, presented by the Rev. H. W. Crosskey, F.G.S. (Abstract.) Several contributions of interest and importance have been received respecting the position and distribution of erratic blocks. A granite boulder 3 X 2'5 X 2 feet has been found by Mr. Hall, in the village of Bickington, parish of Fremington. There is no similar rock nearer than Lundy Island, twenty-five miles west-north-west from the boulder and Dartmoor, twenty-five miles south by east. Its height above the sea is 80 feet. Among the most remarkable erratic blocks yet described in the midland district, are those reported upon Frankley Hill, at a height of 650 feet above the sea. They were examined by the writer in company with Prof. T. G. Bonney, and the following is a summary of the observations made: A section of drift beds is exposed in a cutting of the new Hales Owen Railway passing through Frankley Hill. The section is as follows:-Permian clay, sand of clayey texture, yello vish sand, greyish sandy clay with brinter pebbly clay, somewhat sandy. The heights of the clays and sans are very irregular throughout the section which is in itself about 60 feet in depth. Fragments of permian sandstone (which is exposed in a part of the section) are scattered through the sands and clays, but erratic blocks are rare. Indeed, one only-a green-stone-was noticed in the cutting itself, although others doubtless occur. No part of this section can be called a "boulder clay"-if by "boulder clay" be meant either a clay formed beneath land ice, or a clay carried away by an iceberg and deposited on the seabottom, as the berg melted or stranded. 66 The various sands and gravels have all the appearance of being a 'wash" from older beds, effected during the depression and subsequent upheaval of the present land surface. They are neither compactly crowded with erratics, nor are fragments of local rocks heaped irregularly together, and grooved and striated. The way in which the pieces of native rock are scattered through the beds, does not indicate any other force than that which would be exerted by the ordinary "wash" of the waters during the movements just mentioned. The presence of a few erratics shows that the wash must have taken place beneath the waters of a glacial sea, over which icebergs floated. These beds appear to have been formed in the earlier rather than the later part of the glacial epoch. In a field on the summit of the section a large number of erratics are to be seen which have been taken from a recent surface-drain. Twenty of these boulders are felsite, two are basalt, one is a piece of vein-quartz, and one is a Welsh diabase. They constitute a group of allied rocks, evidently from one district. Probably they belong to the great Arenig dispersion. Two of the felsites close to the group are of considerable size, the larger being about 6 X 4 X 2 feet. Similar blocks may be traced to the summit of the hill. One felsite boulder opposite the Yew Trees is about 4'5 X 3X 2 feet, and is partly buried in the ground. The height of the boulders above the sea is remarkable, their highest level being 650 feet. This indicates a corresponding depression of the land, since no Welsh glacier could have travelled over hill and down dale to this summit-level. To render any such glacier work conceiv. able, the Welsh mountains must have stood at a height beyond any point for which there is the slightest evidence. This group of boulders on Frankley Hill appears to have been dropped by an iceberg travelling from Wales upon the top of the clays and sands exposed in the railway cutting at a time when the land was depressed at least 700 feet. In the clays and sands upon which the summit group of erratics rests, we must have beds belonging to an earlier date than the close of the glacial epoch; and the erratics in the cutting must be discriminated from those left at the higher level. Some remarkable boulders were described from the neigh bourhood of Wolverhampton: (1) a striated boulder of felsite 11 X3 X 3 feet; (2) one of slate, broken into two parts, but which, when whole, measured 1125 × 6.25 X 3'5 feet; (3) one of granite about 4'75 feet in each dimension, and weighing about three tons. Mr. D. Mackintosh traces the origin of the so-called " 'greenstone" boulders (more properly to be called diorites or dolerites) around the estuaries of the Mersey and the Dee. The area in which they are very much concentrated is intensely striated, and nearly all the striæ point divergently to the south of Scotland, i.e., between N. 15° W. and N. 45° W. A large "greenstone" boulder has been found at Crosby, resting on a perfectly flat glaciated rock surface, with stric pointing N. 40° W. Additional presumptions in favour of the Scottish derivation of these boulders may be found (1) in the fact that nearly all these boulders consist of basic rocks similar to some found in locally concentrated on the peninsula of Wirral and the neighthe south of Scotland, and (2) in the extent to which they are bouring part of Lancashire. Many fresh greenstone boulders have been lately exposed in the newest Bootle Dock excavation. The largest is 6 X 4'5 X 3 feet, and was found on the surface of the upper boulder clay. As a rule these boulders are excessively flattened and regularly grooved. Mr. J. R. Dakyns describes the occurrence of Shap granite boulders on the Yorkshire coast. There are several at Long Nab on the north side of the Nab; one of these measures 3 cubic feet. Others are on the north side of Cromer Point; south of Cromer Point there are more till you come nearly to Filey. There is one measuring 3 X 2'5 X 2 feet on the top of the cliff about a mile from Filey. It is probably practically undisturbed, for the ground slopes inland from the cliff, and therefore, if it has been turned up in ploughing and moved, it cannot have been moved far, for no one would take the trouble to cart a huge boulder far up-hill. There are several boulders of Shap granite on the shore along Flamborough Head. the north of Filey Bay, but none along the south till one reaches Several occur along the shore between Flamborough Head and Flamborough south landing; one of these measures 36 cubic feet. One may be seen rather more than a mile south of Bridlington Quay, and doubtless they have travelled still further south, since there is one built into a wall at Hornsea. The destruction of erratic blocks is going on so rapidly that the Committee invite continued contributions of information concerning them. Report of the "Geological Record" Committee, by W. Whitaker, B.A., F.G.S.-Since the last meeting of the Association the third volume of the "Geological Record" has been published. This gives an account of books, papers, &c., on geology; mineralogy, and paleontology published at home and abroad during the year 1876. The fourth volume (for 1877) is in the press; and part of the MS. for the fifth volume (for 1878) is in hand. The average size of the three published volumes is 440 pages, each volume recording over 2,000 papers, &c. Fifteenth Report of the Committee for Exploring Kent's Cavern, Devonshire. Drawn up by W. Pengelly, F.R.S.-Work during the past year has been carried on in the "High Chamber" and its branches. This chamber extends for about 53 feet in a northwesterly direction from the "Cave of Inscriptions." At its inner or north-western end it sends off two branches; the northern branch was excavated for about 12 feet, when the work was abandoned, as breccia, blocks of limestone, and crystalline stalagmite reached the roof and rendered further progress difficult and expensive. The "High Chamber" contains only breccia, the oldest mechanical deposit in the cavern, and the crystalline stalagmite which overlies it. Bones of bears and implements have been found in the breccia here, and some recent objects were found on or near the surface. The southern branch of the High Chamber is called the "Swallow Gallery," from a swallow. hole which occurs about 18 feet from the entrance. This has been explored for about 50 feet. It also contains only breccia, generally lying bare, but covered with crystalline stalagmite at the inner part of the chamber. Here too the remains consist chiefly of bear; a few implements have also been found. There were entrances to the cavern by the Swallow Gallery and through the swallow holes; but these were quite closed before the beginning of the "cave-earth era," and have since remained so. Excavations have also been made in Clinnick's Gallery; but here, as in former years, the number of "finds" has been small. Prof. A. Leith Adams has availed himself of the collection of mammoth remains made during several years from Kent's Cavern, to illustrate his memoir for the Paleontological Society on "British Fossil Elephants." Extracts from this memoir are given in the report, and especial mention is made of a molar found in 1874 in the "Cave of Rodentia." Prof. Adams says:"This tooth is one of the smallest milk-molars of any elephant with which I am acquainted, and is even more diminutive than the first milk-teeth of the Maltese pigmy elephants." Report on the Miocene Flora, &c., of the North of Ireland, by W. H. Baily. The plants occur, between two beds of basalt, in a deposit of brown and red bole, and immediately overlying a bed of pisolitic iron ore, which has been extensively worked. Twenty-five species of plants have been determined; they are most closely allied to the fossil flora of North Greenland, some of the forms also occurring at Bovey Tracy. Sixth Report of a Committee consisting of Professors Herschel and Lebour, and Mr. J. T. Dunn, to determine the Thermal Conductivities of certain Rocks, showing especially the Geological Aspects of the Investigation.-The research and correspondence which it would require to complete a historical sketch of the attempts already made to determine by experiments the thermal conductivities of the most widely distributed terrestrial rocks, which the Committee proposed to prepare during the past year, are not so far advanced at present as to allow them to be comprehended in this year's Report. But the Committee hopes during the coming year by continuing its inquiries with the addition to its numbers of the names of Professors W. E. Ayrton and J. Perry, of the Imperial College of Engineering in Japan, to carry out the object of its undertaking, so as to exhibit the state of our knowledge of the data of thermal conductivity of those widespread kinds of rock which constitute the external materials of the globe. mination of the conductivity of sand and gravel strata, such as make up the materials of Greenwich Hill, upon which the Royal Observatory is placed. Report of the Committee, consisting of Prof. Sir William Thomson, Prof. Clerk-Maxwell, Prof. Tait, Dr. C. W. Siemens, Mr. F. 7. Bramwell, and Mr. J. T. Bottomley for commencing Secular Experiments upon the Elasticity of Wires, by J. T. Bottomley. At the last meeting of the British Association, the arrangements for suspending wires for secular experiments in the tube which ings, and for observing these wires, were described and reported has been erected in the tower of the Glasgow University Buildas complete. Some improvements have since been found necessary; but, so far as these are concerned, there is not much to add to the report then given. The long iron tube has been closed at the top and bottom so as to keep out currents of air and dust, and the joints of the tube have been carefully caulked. Some improvements in the cathetometer used for observing the marks on the wires were also found to be required, but the instrument is now satisfactory. Six wires have now been suspended in the tube; their stretching weights have been attached to them, and they have been carefully marked and measured. These wires are suspended in pairs-two of gold, two of platinum, and two of palladium. One of each of the pairs is loaded with a weight equal to onetwentieth of its breaking weight, and the other of each pair The with a weight equal to one-half of its breaking weight. points of suspension for each pair are very close together, so that any yielding of the place of support affects both wires equally. Each wire is marked with paint marks, and there are other marks on the wires and on the weights attached to them where positions have been determined. These marks are described in a laboratory book which is at present kept in the room of the professor of natural philosophy in the University of Glasgow. The measurements that have been made, and the experiments that have been undertaken in connection with the work assigned to the Committee, are all being entered in this book. This, however, can only be regarded as a temporary mode of keeping these records. It is intended that the record in this book shall contain 1. Description of the tube and arrangements for suspending the wires, and for suspending additional wires at future times, and description of the mode of attachment of the stretching weights. 2. Description of the cathetometer and method of measuring the changes, should there be any, in the lengths of the wires. 3. Description of the wires themselves, and record of experiments that have already been made on them as to breaking weight and Young's modulus of elasticity. 4. Description of the marks put on the wires, and record of the measurements that have been made as to the lengths of the wires and as to the relative positions of the marks at the time of suspending the wires. The The stretching weight and the clamps attached to the wires are engraved each with the amount of its weight in grammes. measurements are all made in grammes and centimetres. It seems desirable, considering the nature of the experiments that are just now commencing, that information regarding them should be preserved to the British Association in some appro priate way; and that provision should be made for recording every change that may take place, and for communicating from time to time to the Association such information as may be obtained. In the report presented to the Association by this Committee last year, it was mentioned that experiments had been commenced in the laboratory of the University of Glasgow in connection with the present investigation on the effects of stress maintained for a considerable time in altering the elastic pro The Committee has obtained during the past year some measurements of thermal conductivities both of rocks and ebonite, and india-rubber, and corroborates the very low value found by Prof. Stefan, of Vienna, for the conductivity of ebonite. It has also corrected some imperfections of its former tables, by showing that the values given in them have throughout been described too low, by about an eighth of their assigned values, and find that with this correction their results have been in close accord-perties of various wires. These experiments are still being ance with the measures that Sir William Thomson and cther observers deduced of the conductivities of soils and rocks in places where underground thermometers have been sunk and read regularly for many years. The records of such thermometers in the grounds of the Royal Observatory at Greenwich have been preserved continuously for more than thirty years, and the last volume of "Greenwich Meteorological Reductions " contains the observations of their temperatures for twenty-seven successive years, 1847-73. This record (already used in part by Prof. Everett) might now afford a new and very valuable deter carried on, and results of interest and importance have been already arrived at. The most important of these experiments form a series that have been made on the elastic properties of very soft iron wire. The wire used was drawn for the purpose, and is extremely soft and very uniform. It is about No. 20 B. W. G., and its breaking weight, tested in the ordinary way, is about 45 lbs. This wire has been hung up in lengths of about 20 feet, and broken by weights applied, the breaking being performed more or less slowly. In the first place, some experiments have been tried as to the smallest weight which, applied very cautiously and with precautions against letting the weight run down with sensible velocity, will break the wire. These experiments have not yet been very satisfactorily carried out, but it is intended to complete them. I lb. per day. 46 8.13 III. IV. 8.81 Broken by accident. The other experiments have been carried out in the following way:-It was found that a weight of 28 lbs. does not give permanent elongation to the wire taken as it was supplied by the wire drawer. Each length of the wire, therefore, as soon as it was hung up for experiment, was weighted with 28 lbs., and this weight was left hanging on the wire for 24 hours. Weights were then added till the wire broke, measurements as to elongation being taken at the same time. A large number of wires were broken with equal additions of weight, a pound at a time, at intervals of from three to five minutes-care being taken in all cases, however, not to add fresh weight if the wire could be lb. per day. seen to be running down under the effect of the weight last added. Some were broken with weights added at the rate of one pound per day, some with three-quarters of a pound per day, and some with half a pound per day. One experiment was commenced in which it was intended to break the wire at a very much slower rate than any of these. It was carried on for some months, but the wire unfortunately rusted, and broke at a place which was seen to be very much eaten away by rust, and with a very low breaking weight. A fresh wire has been suspended, and is now being tested. It has been painted with oil, and has now been under experiment for several months. The following tables will show the general results of these experiments. It will be seen, in the first place, that the prolonged application of stress has a very remarkable effect in increasing the strength of soft iron wire. Comparing the breaking weights for the wire quickly broken with those for the same wire slowly broken, it will be seen that in the latter case the strength of the wire is from two to ten per cent. higher than in the former, and is on the average about five or six per cent. higher. The result as to elongation is even more remarkable, and was certainly more unexpected. It will be seen from the tables that, in the case of the wire quickly drawn out, the elongation is on the average more than three times as great as in the case of the wire drawn out slowly. There are two wires for which the breaking weights and elongations are given in the tables, both of them " bright" wires, which showed this difference very remarkably. They broke without showing any special peculiarity as to breaking weight, and without known difference as to treatment, except in the time during which the application of the breaking weight was made. One of them broke with 44 lbs., the experiment lasting one hour and a half; the other with 47 lbs., the time occupied in applying the weight being thirty-nine days. The former was drawn out by 28.5 per cent. on its original length, the latter by only 4'79 per cent. Tables showing the Breaking of Soft Iron Wires at Different I.-WIRE QUICKLY BROKEN lb. per day. ... It was found during the breaking of these wires that the wire becomes alternately more yielding and less yielding to stress applied. Thus, from weights applied gradually between 28 lbs. and 31 or 32 lbs., there is very little yielding and very little elongation of the wire. For equal additions of weight between 33 lbs. and about 37 lbs. the elongation is very great. After 37 lbs. have been put on, the wire seems to get stiff again, till a weight of about 40 lbs. has been applied. Then there is rapid running down till 45 lbs. has been reached. The wire then becomes stiff again, and often remains so till it breaks. It is evident that this subject requires careful investigation. Report of the Committee for effecting the Determination of the Mechanical Equivalent of Heat.-The Committee had little to report this year, the work in progress being the protracted one of supplying a means of correcting errors in the determination of the temperature arising from the temporary changes of the fixed points of thermometers constructed of glass. They had learned with pleasure that an extensive series of experiments had recently been made by Prof. H. A. Rowland, of Baltimore, who, being unaware of what had been done by the Committee, had arrived at an equivalent almost identical with that determined by Mr. Joule. Report of the Committee appointed for the Purpose of endeavouring to procure Reports on the Progress of the Chief Branches of Mathematics and Physics.-Owing to unforeseen circumstances no meeting of this Committee has taken place during the past year. It seems desirable, nevertheless, in order that the question of the reappointment of the Committee may be fully considered, and that there may be a full expression of opinions on the subject referred to it, that a statement should be made to the Section of the proceedings of the Committee, the more so since, in the hope that greater progress would have been made by this time, no report was presented at the last meeting of the Association. The first matter discussed by the Committee was the character and general plan of the reports which they should endeavour to procure; the next was to what extent or in what manner the production of such reports could be aided by the Committee. Important contributions to the discussion of these questions are contained in written communications to the Committee from two of its members, Professors Clerk-Maxwell and Stokes. Prof. Clerk-Maxwell writes as follows: "Reports on special branches of science may be of several different types, corresponding to every stage of organisation, from the catalogue up to the treatise. "When a person is engaged in scientific research, it is desir able that he should be able to ascertain, with as little labour as possible, what has been written on the subject and who are the best authorities. The ordinary method is to get hold of the most recent German paper on the subject, to look up the references |