The Newcastle meeting of the British Association 1889 : report of proceedings reprinted from the "Newcastle Daily Chronicle".

British Association for the Advancement of Science. Meeting

Date:: [1889?]

Credit: The Newcastle meeting of the British Association 1889 : report of proceedings reprinted from the "Newcastle Daily Chronicle". Source: Wellcome Collection.

193/238 page 189

$ture is raised, the latter in a very marked degree. There are also experiments showinpr a still more con.siderablo de- crease of tenacity in f^un-metal. The author's attention was directed to the matter in studying some experimeiitsinade fortheAdmiraltyinl877. In theseexperimentscopper.Muntz metal, and phosphor bronze showed a tolerably regular de- crease of tenacity as the temperature was raised to SOOdeg.F. But in the case of gun-metal the results were more anomalous. The gun-metals tried were all alloys of copper, tin, and zinc. In the bars tried the tenacity diminished tolerably recularly up to a temperature of 300 deg. or 350 deg. But beyond that tetui)eracure there was a sudden decrease of tenacity generally of more than 50 per cent., and at a temperrture of 500deg. in several cases the tenacity had become nil. Now at the high pressures, and correspondingly high temperatures, at which steam-engines are often worked, giiii uK^tal is ex- posed in many cases to temperatures of 350 deg. or 400 deg. It is practicaily important to know if at such tem- peratures its strength is seriously impaired. At any rate, the author found that there were but few experiments on the strength of alloys at different temperatures, and of some of these the trustworthiness was doubtful. Hence It appeared that it might be useful to make some new experiments. In the present experiments the bars to be tested were fixed in an oil-bath heated by a gas-jet. The middle part of the bar for a length of two inches was turned down to a diameter of i inch or 5-16th inch. The temperatures were taken by a mercurial therinometer. it is believed that the temperatures are quite accurate except those above 600 deg. Above 600 deg. the ther- mometer behaved irregularly. The bars were broken in a small special testing-machine of the manometer type, the pressure on the diaphragm being balanced by a mercury column. Rolled bars of yellow brass, Muntz rnetal, and Delta metal were tried, and the results on these are quite regular. Some bars of cast brass also gave verv fairly regular results. The bars of gun-iuetal gave results of less regularity. This is due, in parts at all events, to the face that some of the bars cast first proved unsound, and new bars had to be cast to replace them. At some future time the author hopes to try a series of gun-metal bars all cast at the same time, iiie results were plotted in a diagram, and show that in all cases the decrease of strength follows a regular law without any such sudden loss of strength as was shown m the Admiralty experiments. Even at temperatures of 600 deg. to 650 deg. all the bars had a not inconsiderable tenacity. The ultimate elongation of the bars in the two- inch test length was measured, and is given in the table, ihere is a pecubarity in the influence of temperature on the ductihty of the bars. In most cases the ultimate elongation diminishes with increase of temperature With Muutz metal the decrease is regular, and there is still considerable elongation before fracture at a tem- perature of 650 deg. With yeUow brass (rolled) the decrease is more rapid, and there is very little elongation before fracture at temperatures above 500 de Oast brass behaves in the same way. The elongations of the Run-metal bars were very irregular, and at tempera- tures of 600 deg. and upwards the elongation was ex- tremely small. On the other hand, in the case of the -Delta metal bars the elongation increased regularly with increase of temperature. The contraction of area was also measured. This follows generally the same law as the elongation at fracture, but the contractions of area are more irregular than the elongations. The Pkesiuent advocated the desirability of investi- gating the behaviour of alloys both in reference to the periodic law to which Professor Roberts-Austen had called attention, and also to the properties which resulted from various combinations of metals when these metals were in a state ot absolute purity. The mixture of alloys had been conducted under a mere rule of thumb. There must be some laws, which investigation would make RIVER VOLUMES, &o. A paper by Mr. C. E. de Ranok was read, in the absence of the author, on Records of River Volumes and Flood Leve s The author in his paper said :-The basis of any legislation for the amelioracion of floods should be an accurate knowledge of the levels reached by the dry-weather flow, the average flow, and the Hood conailion of our streams, extending over a long period ; at present such information is rarely obtainable and, except m waterworks drainage areas, but few observations exist as to the actual volume of water run off daily by the rivers of this country. There can be little doubt that a permanent record of tlie height of floods, and the volume ot the daily flow of our streams, is a mat- ter of national necessity, and that such records could easi y be obtained by the County Councils throughout the kingdom. Were gauges painted on the county bridges by the county surveyors, a record could be made at least once a day by the county police on their ordinary rounds. It the leet cm the gauges were painted with the actual height above the Ordnance datum, it would facilitate com- parison. At important points on large stre.iins automatic recording appliances might be placed under the direct charge of the county surveyor, who at such points might daily ascertain the number of cubic feet of water carried down. Where a river basin extends through two or more counties, the provi- sion for joint action of a Watershed Board seems to be already provided for, or suggested, by the Local Go- vernment Act of last year. The author hoped the com- imttee ot the bection would think the matter of sufficient importance to bring it before the Council, and that they would be inclmed to concert such measures as would brin| liis suggestions, or a modification of them, before the Ijocal (Government Board, with the view of their giving the necessary sanction for such observations being carried out by the county officials. HEATING FROM CENTRAL STATIONS. In the absence of the author, the RECOEDEKfMr. Rie-e) read a paper by Mr. W. W. Phipsou, on Central Station Heating and Power Supply. The author com- menced his paper by commenting upon the growing neces- sity of a central heating and power supply for cities and large towns, and of the dangers and inconveniences of the present system. He took for his model the scheme in successful operation since 1887, in Boston, U.S. which is known as the Prall System, and exemplified by the Boston Heating Company. This system consists in the constant circulation of water at a high temperature and pressure (viz. at 400 deg. Fahr., and 250 lbs.) on the square inch) from the batteries of boilers at the central station through the supply mains, and back to the boilers by means of the return mains, the circulation being maintained by means of pumps. The ample scope of the system was next entered upon, showing that it was quite adequate to meet all requirements as regards both heat and power. The method of determining the amount of heat or power supplied to the consumer was described. With regard to the loss of heat by radiation, it has been reduced to a minimum by covering the mains with a non- conducting material, reducing the internal temperature of 400 deg. of the pipe to 110 deg. on the outside of the covering. The construction of the pipe trenches, or con- duits was described, together with the sizes of mains. &c. Ihe details of the construction of the mains were fully given, showiner that expansion-joints are -ised, which are fixed at every 100 feet to 150 feet, as well as one where the main changes direction, and of the special connexion used in coupling the pipes together. Service-boxes to supply three houses are fixed under the footpaths which are connected to the mains by a pipe 1 inch in diameter. J^rom these boxes the house supply is taken by means of copper pipes i inch to 1 inch in diameter. At the end of the copper pipe, and inside the house, is fixed a vessel called a converter, whose use is to permit the water to resolve itself into steam, the pressure of which is con- trolled by means of a reducing valve fixed on Trf.J°^lf^ ^''''^ ^''^'■^ }^ the converter. ±rora this converter the house services are taken. If a supply of both heat and power is required, double or compound converters are used with two reduc- ing valves, the power being taken from one and the heat from the other. The pumping and boiler ca]iacity of the central station were given, together with the latest addi- tions to ensure economy of labour. The paper concluded$