Improvements in Chlorimetry.-Mr. J. Smith, M.A., read a paper before the British Association at Edinburgh on "Improvements in Chlorimetry." He showed that the use of the milky solution of bleaching powder in chlorimetry is unsatisfactory, and hence it was necessary to discover a method of securing a clear solution containing all the chlorine by dissolving it in an alkaline solution. This is conveniently done by adding, say, ten grammes of bleaching powder to twenty grammes of soda crystals, filtering out the precipitated carbonate of lime, which is known to be washed, when it no longer discharges the colour of dilute sulphate of indigo, and making up the filtrate by water to one like of fluid. It is a clear colourless liquid of the specific gravity of 1-007, but if made of specific gravity 1-233 slightly greenish, having a pleasant oily feeling between the fingers, contrasting favourably with the roughness of the decanted solution of the bleaching powder with which it gives a precipitate. Most satisfactory results are obtained from it by all the chlorimetrical methods, and it has the additional advantage of showing the amount of lime in the sample by adding a solution of known strength of carbonate of soda until a precipitate is no longer formed.

Dichroism of the Vapour of Iodine.-Professor Andrews read a paper before the British Association on "The Dichroism of the Vapour of Iodine." The fine purple colour of the vapour of iodine, he explained, arises from its transmitting freely the red and blue rays of the spectrum, while it absorbs nearly the whole of the green rays. The transmitted light passes freely through a red copper or a blue cobalt glass. But if the iodine be vapour sufficiently dense, the whole of the red rays are absorbed, and the transmitted rays are of a pure blue colour. They are now freely transmitted as before by the cobalt glass, but will not pass through the red glass. A solution of iodine in sulphide of carbon exhibits a similar dichroism, and, according to its density, appears either purple or blue when white light is transmitted through it. The alcoholic solution, on the contrary, is of a red colour, and does not exhibit any dichroism.

The Phosphate Process with Sewage.-Messrs. Forbes and Price described their process to the British Association. This process, it was stated, was in operation at Tottenham. The sewage, after passing through some depositing tanks which had been constructed for the lime process, was pumped up at the rate of 800 or 1,000 gallons per minute along a carrier into a tank a hundred yards long, and of gradually increasing breadth. This tank took three hours to fill. As the sewage passed along the carrier the chemicals were mixed with it thus :-Two boxes were placed over the carrier—one a few yards further along it than the other; the first contained the phosphate mixture, and the second milk of lime. Men were continually stirring the contents of each box, which were allowed to run continuously into the sewage as it passed beneath the boxes. The amount of the preparation added was not ascertained, but it was stated to be certainly much less than the proportion indicated by previous experiments (one ton to 500,000 gallons of sewage).

GEOLOGY AND PALEONTOLOGY.

Discovery of the Opercula of Hyolithes.—Mr. W. S. Ford announces this discovery from New York, in "Silliman's American Journal." He says that several weeks ago, being in Montreal, he showed Mr. Billings, Palæontologist of the Geological Survey of Canada, a small collection of fossils that he had made in the Primordial rocks near New York. He pointed out to him, that among them there were the opercula of two species of Hyolithes. One is a minute circular species with four pairs of lateral muscular impressions, and two smaller, dorsal, all radiating from a point near one side. The other species is larger and like a Discina on the outside. Mr. B. showed him several specimens of the smaller species, that had been collected by Mr. T. C. Weston of the Canadian Survey last summer, in rocks of the same age below Quebec. He is informed that this is the first discovery of the opercula of Hyolithes yet made on this continent. He has made some observations on the rocks of this vicinity, and collected a number of species of fossils, of which he hopes to give an account at an early date.

The Geology of the Rocky Mountains.—We learn from one of our American contemporaries published in August, that Professor Marsh of Yale College, with twelve other gentlemen, has started for the Rocky Mountains and Pacific Coast. He will be absent until winter, and will continue his investigations of the Tertiary and Cretaceous formations which his explorations last year proved to be very productive in new species of vertebrates. What is Coal? This question is answered in a very able paper by Professor Dawson, LL.D., in the "Monthly Microscopical Journal" for August. He says that-1. The mineral charcoal or "mother coal" is obviously woody tissue and fibres of bark; the structure of the varieties of which and the plants to which it probably belongs, he has discussed in another paper. 2. The coarser layers of coal show under the microscope a confused mass of fragments of vegetable matter belonging to various descriptions of plants, and including, but not usually largely, sporangites. 3. The more brilliant layers of the coal are seen, when separated by thin laminæ of clay, to have on their surfaces the markings of Sigillaria and other trees, of which they evidently represent flattened specimens, or rather the bark of such specimens. Under the microscope, when their structures are preserved, these layers show cortical tissues more abundantly than any others. 4. Some thin layers of coal consist mainly of flattened layers of leaves of Cordaites or Pychnophyllum. 5. The Stigmaria underclays and the stumps of Sigillaria in the coal roofs equally testify to the accumulation of coal by the growth of successive forests, more especially of Sigillariæ. There is, on the other hand, no necessary connection of sporangite beds with Stigmarian soils. Such beds are more likely to be accumulated in water, and consequently to constitute bituminous shales and cannels. 6. Lepidodendron and its allies, to which the spore-cases in question appear to belong, are evidently much less important to coal accumulation than Sigillaria, which cannot be affirmed to have produced spore-cases similar to those in question, even though the observation of Goldenberg as to their fruit can be relied on; the accuracy of which, however, he is inclined to doubt.

South of Scotland Silurians.—Mr. J. D. Brown read a paper on these before the British Association at Edinburgh. The object of the paper was to show that the silurian rocks of the south of Scotland, as developed in Dumfriesshire and Peeblesshire, are not all one geological epoch, as has been hitherto supposed, but belong to two different epochs-a lower one represented by the Moffat rocks, well known by their beds of anthracite shales and graptolites, and an upper series of later age, which lie unconformable on the Moffat rocks. These beds have been long known at Wrae and Glen Cotho, and more recently in Galashiels, through the exertions of Messrs. Lapworth and Wilson.

New Fossil Reptiles from the Cretaceous and Tertiary Formations.-Professor C. O. Marsh describes several of these remains in "Silliman's American Journal" for June. The remains were collected by the Yale College party during their explorations last summer in the Rocky Mountain region. The specimens from the Cretaceous formation are of great interest, as they further illustrate the remarkable development in this country, both in numbers and distinct forms, of the Mosasauroid Reptiles, which appear to have been comparatively rare in other parts of the world. Fortunately, moreover, some of these remains serve to clear up several obscure points in the structure of these reptiles, and prove conclusively that they had a well developed pelvic arch and posterior limbs; although up to the present time no satisfactory indication of this had been discovered, and the eminent palæontologists who have recently made these animals an especial study consider them probably destitute of these extremities. The remains found in the Tertiary deposits are also of importance, since they show that types of reptilian life, almost unknown hitherto from that formation in the West, were, in one of the ancient lake basins at least, abundantly represented there during that period.

A huge Pterodactyl.—We learn from the "American Naturalist” (July) that Professor Marsh states that the Yale College party obtained, in addition to the cretaceous fossils already described, several specimens which indicate a huge flying reptile, which he names Pterodactylus Owenii. The bones discovered "indicate an expanse of wings not less than twenty feet." The remains were found by Professor Marsh in the upper Cretaceous formation of Western Kansas. This is the first occurrence of the pterodactyl in America.

The Sivatherium Giganteum.-Dr. J. Murie, F.Z.S., read a paper before the British Association at Edinburgh, stating the systematic position of the extinct Sivatherium Giganteum, in relation to the deer, antelope, and other animals of the same species. The author introduced the paper by some remarks concerning the labours of the late Dr. Falconer and Sir Proby Cautely. These eminent men, the former a distinguished graduate of the Edinburgh University, brought to light, in their researches of fossil fauna of the Sewalik Hills, several remarkable mammalian forms. The sivatherium, one of these, as attested by its remains, must bave attained the size of a full-grown elephant. It appears, however, to have been a ruminant. In some respects deer-like, in others more resembling the antelopes, still stranger it seems to have had some of the characteristic features of pachyderms, the tapir for example. Dr. Murie went on to show that it belonged to those

radical forms which by some may be regarded as one of the progenitors of diverse herbivorous groups. The sivatherium, according to him, is unlike all other living ruminants but one-the prongbuck-from the fact of its having had hollow horns, evidently subject to shedding. It differs thus from deer whose solid horns annually drop off, and from the antelope tribe, sheep, and oxen, whose hollow horns are persistent. Save one living form -the saiga-no recent ruminant possesses, as did the sivatherium, a muzzle resembling in several ways the proboscis of the tapirs and elephants. On the strength of his own recent researches, and of those of Mr. Bartlett and Dr. Caulfield, Dr. Murie is inclined to place the sivatherium in the family Antilocapridæ. Radiating from the sivatherium can be traced differentiation of structure allying it to the ancient bramatherium and megacerops. Diversely, links lead through the prongbuck towards the deer, giraffe, and camel. On the other hand, configurations point undoubtedly to the saiga, and there it is, as it were, split into lines directed towards the antelope, the sheep, and even the pachyderms.

Flint Implements in Joshua's Tomb.-The Abbé Richard gave an account of this recent discovery to the British Association at Edinburgh. He thinks that it upsets all geological hypotheses as to man's size. The Abbé unfortunately forgets (1) that the tomb may not be that of Joshua at all, and (2) that, if it be, there is no evidence as to the time the flint weapons were placed there. In fact they may have been, and probably were, there many ages before Joshua was placed there.

Bats of the present and of the Mammoth Periods.-Professor Van Beneden read a paper, in French, with this title, before the British Association. So far as was gathered, it was an argument against the Darwinian theory.

MECHANICAL SCIENCE.

The Rhysimeter.—Under this name, Mr. A. E. Fletcher has described, to the British Association, an instrument for measuring the velocity of streams of water, or the velocity of a ship relatively to the water through which it is moving. The apparatus is very simple. A double tube, with two orifices at the bottom, one of which faces the source of the current, while the other faces the opposite direction, is held in the stream, and communicates by tubes with the indicator where the pressure is measured, by columns of ether, water, or mercury, according to the circumstances of the case. The rhysimeter is already employed on some of the mail packets running to the United States, in place of the patent log, to ascertain the speed of the ship. It is more convenient, as giving the speed directly, without a time observation. The principle of the instrument is not new, but the construction is an improvement on previous instruments.

Light Railways.—Mr. W. Lawford has read a paper on this subject before the Institute of Mechanical Engineers. By light railways, Mr. Lawford understands railways of the ordinary narrow gauge, constructed as branches from existing trunk lines, but intended to be worked with light, flexible rolling stock, and at slow speeds. With a maximum load of 5 tons on one

pair of wheels, such railways might be constructed for 3,000l. to 3,500l. per mile of single way. Mr. Lawford described a short line of this description, constructed for the Duke of Buckingham and Chandos at Wooton. This line, of 6 miles in length, with a branch of 13 miles, is essentially a surface line, the highest embankment being 12 ft. and the deepest cutting 10 ft. Turnpike and other roads are crossed on the level. The rails are 30lb. bridge rails on longitudinal timbers. The ballast is 10 ft. wide and 6 to 9 in. thick under the sleepers.

Compound Engines of the "Tenedos."—In the recent trial of the engines of the "Tenedos," the consumption of fuel, in the six hour runs, varied from 1.58 lbs. per I. H. P. per hour, at eight-knot speed, to 2·32 lbs., at thirteen-knot speed. The rate of expansion of the steam was 9 times in the former case and 6 times in the latter case. These results are extremely satisfactory.

Water Power.-The Industrial Society of Mulhouse has recently received communications about a project for utilising the fall of the Rhone at Bellegrande. According to the calculations of M. Colladon, of Geneva, this fall of thirteen metres could be utilised so as to afford 10,000 horses power. An American company, employed in the production of phosphate of lime, proposes to construct a tunnel for utilising this fall, and offers to Alsatian manufacturers to erect at Bellegrande establishments similar to those they possess at present. (Paris Correspondent of Engineering.)

Self-acting Rudder.—At the International Exhibition of Naples, Signor Siciliano, of Palermo, exhibited an arrangement for working the rudder of a ship by means of electro-magnets. The currents which actuate the electro-magnets are under the control of the ship's compass, any deviation of the compass from an assigned direction completes an electric circuit, which in turn, through the electro-magnets, acts on the rudder. Thus the compass and rudder form a perfectly automatic arrangement.

MEDICAL.

Volumes of the Cavities of the Heart.-Professor the Rev. Samuel Houghton, F.R.S., in his recent lecture (June 24) before the Royal Institution, attempted to compute the volumes of the ventricles of the heart. Admitting the principle of least action, he said: "I can predict a thing that at first sight appears very strange. I can find the ratio which the volumes of the two cavities bear to each other by the measurement of the lengths of the fibres that surround them. On measuring these fibres it comes simply to this. Let L be the length of the fibres that go round the entire heart: let be the length of the fibres that go round the left ventricle. Find those lengths and cube them. The ratio of those cubes will be proportional to the sum of the right and left ventricles divided by the left. There are theoretical grounds which I believe are almost of themselves sufficient to entitle us to believe that these two cavities are of equal volume, and therefore that this fraction will come out equal to 2. I have taken, however, a more certain mode of determining this by collecting together all the obser