Further details of the improved condition, for the purposes of navigation, are also added in the paper. But another object of the paper is to endeavour to provide data for the recalculation of the data of the tidal régime, as amended by the above results, by what is known as the method of harmonic analysis.' This method of harmonic analysis' of the tides was first brought before the British Association in 1872 in a long report by Sir William Thomson (now Lord Kelvin), Professor J. C. Adams, Professor Rankine, and others. A further report, however, on the subject, and illustrative of the method, as used in the reduction of the Indian tidal observations, was presented at the 1883 meeting in Southport by Professor G. H. Darwin and Professor J. C. Adams. Since then, in 1885, Professor G. H. Darwin has communicated to the Royal Society the data, resulting from the harmonic analysis of the tides at Liverpool. It is urged, however and apparently on good authority-that the actual data now afforded by the tidal régime of the Mersey, resulting from the changes referred to at the commencement of the paper, are such as to render it advisable to again submit the Mersey tides to a further examination by 'harmonic analysis.' The writer would suggest that a Committee might be formed, with the object of obtaining the necessary Tidal data, and in a form suitable for Harmonic Analysis thereof. 9. History of the Discovery of Natural Gas in Sussex, Heathfield District. By RICHARD PEARSON. The first find of gas which has come to my knowledge was made in 1836 at Hawkhurst in West Sussex. Natural gas next appeared during the famous sub-Wealden boring of 1873-75, at a place called Netherfield. The sub- Wealden was started to commemorate the visit of the British Association to Brighton, 1872. Mr. Topley records at 602 feet a bed 1 foot thick, very rich in petroleum. This was in the Kimmeridge clay, 290 feet from the surface. Willet records on this bore: Indications of petroleum became more distinct at about 160 feet from top of the Kimmeridge clay; all below that depth is more or less impregnated with petroleum.' Natural gas was not used to any great extent in America before 1885. It was about that date that Mr. Andrew Carnegie used natural gas in his steelworks. At Heathfield, some time ago, a firm of well-drillers were boring a well for water on the site of what is now the Heathfield Hotel. At 300 feet the borers met an inflammable gas; but as they were seeking for water, and none was reached, the borehole was cemented up and left. In August 1896 men employed by the same firm were at work boring a well for the L. B. & S. C. Railway Company for water; at a depth of 300 feet they also found an inflammable gas. But no water was reached even when another 100 feet had been sunk. Three years afterwards the railway company decided to put the gas to some useful purpose, and ever since the railway station has been lit with natural gas. The consumption is about 1,000 cubic feet per day. Hearing of this very practical outcome of the second discovery, I expected to hear also that explorations would be made to discover the extent of the gasbearing area. But finding that no further steps were taken, I communicated with some American friends, who asked me to take steps. I located positions for six exploratory boreholes to be made; we commenced boring, and in all of the boreholes we have struck gas, at levels varying from 300 to 400 feet from the surface, the farthest borehole of the six being distant some 1,200 yards from the railway station. These six boreholes are started in the geological formation known as the Hastings bed, which-in the Heathfield district-lies some 400 feet geologically 1903. 3 E above the sub-Wealden boring at Netherfield, which was started in the Purbeck bed. This Hastings bed is composed principally of sandstones and iron bands which make it a 'cap' admirably adapted for acting as a natural holder for gaseous volumes. Heathfield is built on the well-known Mid-Sussex anti-clinal. The subWealden boring, started in the Purbeck bed, situated some nine miles east, is on the same anti-clinal. This fact conclusively proves the relative identity of the two discoveries. The Purbeck is well known to be bituminous throughout. The Kimmeridge clay, which lies some 200 feet below the Purbeck, has been proved to be the thickest bed of Kimmeridge in England, and 250 feet of this bed is known to be of a very bituminous nature. Again, the Oxford, lying below the Kimmeridge, is known to be also bituminous. In searching for natural gas in the United States, three things are kept in view : Firstly. Have the rocks been disturbed? (If so, no further time need be wasted looking for gas.) Secondly. Is it an anti-clinal formation? Thirdly. Are there any known bituminous beds below? Holding these points in view, I may say that : 1. In this part of Sussex we have the iron formation of the Hastings sands, practically undisturbed, 2. It is well known to geologists that the North and South Downs are simply the outliers of an enormous anti-clinal. 3. There are three successive bituminous beds proved to lie immediately under the sandstones. At Mayfield, about five miles from Heathfield, we have commenced boring in two positions on the Tunbridge Wells sands. We are now boring over some 200 square miles in the county of Sussex. At Heathfield we are already supplying between seventy and eighty houses with natural gas. We have obtained facilities from the L. B. & S. C. Railway Company to lay our conduit pipes along their lines. The Composition of Heathfield Natural Gas.-The Sussex gas in its natural state gives, in an ordinary Argand' burner, a light of about 12-candle power. Professor Dixon, who I believe analysed Heathfield gas for the Royal Coal Commission, has put on record figures which account for the high illuminant value it has been proved to possess. He gives as its constituents: The great point in the future of Heathfield gas will be its value as used to provide machine power. The engines in use at Heathfield consume about 13 cubic feet to 15 per horse power. The heating power that is to be obtained from a gas containing 93 per cent. of methane is obvious. In an estimate made last year, it transpired that in America one million households and four million people were furnished with this ideal fuel and light. The ironworks of the Wealden area employed some fifty thousand men in 1750, when the coal in the North took the iron-working away from the South. To-day not an ounce of iron is smelted. The fuel is the cheapest in the world, the cost of carriage will be obviated, and in addition to seeing the old industries revived, we shall have opened up an enormous tract of country for new industries which at present is devoted solely to agriculture. The pressure general at Heathfield varies from 134 lb. to 200 lb. per square inch. As to the permanency of the gas, I may state that in China natural gasfrom identically similar geological formations-has been used for evaporating salt for over one thousand years. The United States have some eleven thousand wells bored; we have at present nine, and are in course of sinking ten others. The comparison of gaseous fuels is approximately as follows: Per 1,000 cubic feet at 40° F., and at Atmospheric Fressure. 1. The Effect of Traffic and Weather on Macadamised Roads, and the Prevention of Dust. By T. AITKEN, Assoc.M.Inst.C.E. This paper deals with the problem of improving the structural condition of macadamised roads to withstand the effect of weather and the ever-increasing fast vehicular traffic, especially that of motor cars. After describing the methods followed in connection with the making and repairing of macadamised roads, the author deals in brief with the principal points to be observed when first-class work is required. The quality of the metalling (embracing the trap rocks generally, but more particularly basalt, andesite, felsite, diabase, and some dolerites, being very much superior and less greasy in wet weather than limestone and most granites). The binding material is specially noticed, and also the effect of weather and traffic is described. The smoothness of macadamised roads when properly made compares favourably with street pavements as tested by the viagraph. It is also pointed out that macadamised roads begin to wear at a comparatively early period after being repaired. The causes of this are stated and the probable remedy, so as to ensure greater cementitious power between the component parts of macadamised roads. It is specially pointed out that the binding and not the metalling should be treated, and preferably after the road has been repaired, when contour and surface are at their best. Different methods, recently carried out, of treating macadamised roads with petroleum or tar are mentioned, and the author describes a method by which tar in its natural state can be applied to a road surface in the form of a fine spray, under pressure, the penetration into the binding being from 2 to 4 inches. The experiments carried out show a decidedly improved surface, but adverse climatic conditions, extending for a considerable time past, have precluded information of a reliable nature being recorded. It is pointed out that the time has fully arrived for further improving the structural condition of macadamised roads, and it is to be hoped that the methods adopted and described in this paper will tend in that direction and prove successful. 2. Pendulum Apparatus for Testing Steel as regards Brittleness. The ability of materials in general and steel in particular to withstand shock is a subject of great importance to all engineers, and this paper gives an outline of the systems generally in use for carrying out brittleness tests, with remarks on each; and further explains the use of the pendulum apparatus, as used by Messrs. Willans and Robinson, with the reasons that led to its adoption. Tests by shock or tests for brittleness have from the earliest times been used by engineers, especially on the Continent; and Swedenborg, in 1734, gives some interesting particulars of the rule-of-thumb tests carried out by purchasers of iron in those days; and in nearly every case an impact or brittleness test was used, which though only empirical was no doubt all that was required, and gave a deal of useful information. At the present time, probably owing to the state of perfection to which the testing machine has been brought, there is too much inclination to neglect other properties of material which the usual tests do not detect, but which are quite as important as the usual standard physical tests; and that this is so is shown by M. Fremont's paper, published by the Société d'Encouragement pour l'Industrie Nationale, September 1901, in which he throws an extraordinary light on the brittleness question, and gives several instances where serious fractures in structural and other steel were not accounted for by any of the ordinary testing methods, but were readily explained when tested for brittleness by an impact machine. At Messrs. Willans & Robinson's, Rugby, it has long been felt that a method of testing such as used by M. Fremont and others was wanted to detect the reason for certain fractures which were inexplicable by the ordinary methods used; and an experimental pendulum impact machine was made, and the tests carried out with it gave promise of such good results that a standard machine was made and is in use at the present time, giving results which gain in importance with every series of experiments carried out on it. Many types of impact machines are used, but the pendulum form of apparatus seems to give most satisfactory results: it can be calibrated to give direct readings for energy absorbed, and lends itself to very quick working even by an inexperienced operator. The idea of the arrangement is as follows:-A weight is suspended pendulumwise on a stiff rod, which swings from a centre designed to be as frictionless as possible. This weight or tup is then moved out of the vertical and allowed to fall on to the free end of a test-piece gripped by the other end in a vice, the specimen being notched to locate the break, the height of fall being always made sufficient to cause fracture with one blow. A suitable measuring arrangement is used to record the energy remaining in the weight after fracture of test-piece has occurred; and this subtracted from the calculated energy in the tup before fracture gives the energy required to break the specimen. Measurements are taken of the test-piece, and results are transferred to equivalent energy absorbed on specimen one inch square. The paper is accompanied by drawings of the apparatus and tables of results obtained. 3. Permanent Set in Cast Iron due to Small Stresses, and its Bearing on the Design of Piston Rings and Springs. By C. H. WINGField. Some of Messrs. Willans & Robinson's steam packing rings, each consisting of an outer cast-iron ring' of uniform section, and of the same diameter as the bored cylinder in which it worked, and an inner cast-iron 'spring' ring of section varying as described in vol. II. of Unwin's Machine Design,' under the heading Theory of a Cast-iron Spring Ring,' were tested as to equality of their outward pressures per inch of circumference. Whereas by published formulæ they should have agreed in this respect, it was found that they actually differed considerably. Some springs made specially for the purpose, and having different amounts of follow,' 1 but alike in other respects, were then experimented with by being forced into circular ring-gauges, and being removed and measured after periods By follow' is meant the difference of diameters of the spring when free and when forced into its working position. This difference enabled the combined ring and spring to follow up and compensate for wear. varying from one minute to forty-eight hours. It was found that their diameters were reduced by this treatment, the greater part of the permanent set having taken place during the first fifteen minutes, and that its amount increased with the 'follow' originally given to the springs. It was also found that a measurable amount of set was producible by merely squeezing the rings between the hands. After the rings had been compressed to a definite size for two days or more they acted as reliable springs so long as the initial amount of compression was not exceeded. Some slight inaccuracies in published formulæ applicable to rings formed of materials such as steel, not liable to permanent set from such light loads as piston rings are subject to, were briefly alluded to and a correct formula given; but it was pointed out that that usually published was simpler and sufficiently accurate in use, though not applicable to cast iron. Some elaborate formulæ had been published by E. V. Clark on the Theory of Cast-iron Beams,'' and could perhaps be modified to suit the special case under consideration; but they were not convenient, and the proportions found by direct experiment appeared preferable; moreover the amount of set, and consequently the actual (as compared with the initial) follow, could only be found by trial. The amount of 'spring' in a cast-iron ring with loads not exceeding that which had produced permanent set was much greater than appeared to be generally realised. A spring ring about 5 inches diameter, 0.25 inch thick radially and with its ends about 14 inch apart (after deducting the permanent set), could be bent until they met, and when released they sprang back again to 14 inch apart. 4. A further Note on Gas-engine Explosions. By H. E. WIMPERIS. In the autumn of 1901 the Institution of Mechanical Engineers published the Second Report of the Gas-engine Research Committee drawn up by Professor F. W. Burstall, and in this manner there was presented to the scientific and engineering world a very large mass of experimental results containing most valuable information regarding the internal economy of gas engines. Professor Burstall comes to several conclusions, prominent among which is his contention that the results of his experiments cannot be reconciled without the use of a variable specific heat. The writer has already published in the engineering press an account of certain consequences which follow from this hypothesis, but before the matter could be considered upon a satisfactory basis it was necessary that the classical experiments of Mr. D. Clerk and Mr. Grover should be brought into line. In a paper contributed to the British Association last year, the writer analysed Mr D. Clerk's results and showed that they were in complete harmony with the variable specific heat hypothesis. In the present paper the writer deals with the experiments of Mr. Grover, and shows not only that there is no inconsistency between this hypothesis and Mr. Grover's results, but that by its adoption the explanation of certain difficulties in these results is the more easily given. Thus in the present paper and in the one submitted last year the writer claims to have achieved the object with which he set out--namely to ascertain whether there was anything in past records of experimental work with gas engines which would prove to be incompatible with the adoption of a variable specific heat in all future gas-engine calculations. The conclusion is that there is nothing in the classical investigations of Mr. D. Clerk or Mr. Grover which should afford any ground for hesitation in the matter. 5. Preliminary Experiments on Air Friction. By WM. ODELL, A.R.C.Sc, These experiments were begun with the object of finding a convenient method of determining the power wasted by the windage of flywheels and dynamo armatures. The experiments described at length were made with paper discs, which were mounted on the shaft of an electric motor. Minutes of Proceedings Institution of Civil Engineers, vol. cxlix, p. 313, |