The Bioscope (Oct-Dec 1913)

re re a ae — are inscrung a sketch of the principl+ of the dimmer, which Gf you mean to make a liquid dimmer yourself) will give you a good idea of the arrangement. We cannet call to mind at the moment of writing any suitable deep jar that you could improvise. You might try with the deepest pickle jar you can obtain. = The travel of the elcctrodz: will not be great, but the solution you will require for your small current will be weak, and so we should think the dimming effect can be obtained all right. You would be advised to make up the liquid with special crystals that you can get from theatrical electric supply houses. You must mention whether your current is alternating or continuous, as the crystals for such differ. If your jar hold 1 gallon of hquid we should think about 1 Ib. of crystals would suffice (the cost is about 8d. per Ib.) For ordinary liquid dimmers working well up to their maximum current the proportion is generally 2) Ibs. of crystals per gallon of water. You might bear this in mind, in) case you do not get the effect vou desire, when you can increase the density of the Huid. It should be added that the dimmer should be titted with a switch, so that when the lamps are full on the dimmer can be short circuited. Although in our sketch the switch is shown as a separate hitting to the dimimer, in the theatrical installations the short) circuiting switch is) generally htted to the control wheel, so that the action of the switch is purely automatic. In such a case, however, it is well to have aosluckness in’ the controlling wire, so that the switch closes after the dimmer contacts are together and opens when dimming down before they are apart. If this be not seen to, the great possibility is that the dimmer electrodes will have separated, resistance, therefore, bemg introduced before the switch opens, the lights then dropping suddenly and only finishing out gradually. a * * READER writes regarding the consumption of pas with a pas engine pene: rator plant. Tle wishes to know whether, © when the engine is running and all lights in the buildIng are on, Is any cconomy effected by reducing the number of lights? My engine is otf 20 horse-power, and [T only use forty lights m= the hall and go amperes for the are. 1 wish = to know if I should use more was if I increased th: number of lights. I know I have current to spare. IT might mention that whatever my load, I have not to vary the vas on the enpine.” A CONSTANT The point our correspondent raises is one fre: quently discussed by many who have but a passing acquaintanee with gas engine gen-rators. Certainly, increasing the load means an increase in the gas consumption. , [t is not, however, in direst PeoPyr GOO 1, as the cth ee —— 3 =e. Gee T201 ciency of the engine increases as the load rises. If we consider two extremes--no load and full load—a gas engine will certainly consume many tines more gas in the latter cas2 than when simply running light. At full load a gas engine may consume 22 cubic ft. per brake horse-pow :r per hour, whilst at half load the consumption may be up to 27 cubic ft. per B.H.P. hour. This can be readily understood when it 1s remembered that the engine always has to consume some pas to drive itself before giving out any power, or, rather, before performing any additional work. Suppose a particular engine consumed but 25 cubic ft. of gas per hour In running’ light, and only 25 cubic ft. of gas for each horse power delivered at the fly-whcel. Then, actually, to get 1 horse-power of us-ful work, 50 cubic ft. of gas per hour would be consumed, whereas, with an output of 2 horsepower only 75 cubic ft. of gas would be used. Sse it can readily be seen that the greater the gutput the more efhcient the running. However, It is very rarely that an engine of any power Is used for such a small output, and we should not be far wrong if we said that between half and full load the gas consumption avcraged 22 cubic ft. per brake horse-power hour. It must not be considered that because the eas valve is not touched, the load of an engine doves not vary, as the engine its fitted with an automatic means, either for controiling the amount of gas admitted, or of regulating the yumber of explosions taking place per minute, such an arrangement invariably being controlled by the well-known centrifugal governor. AROUND EALING AND DISTRICT. In addition to the usual strong programme at the Walpole on Friday last, Miss Phyllis Barnes-Moss, who saved a man trom drowning at Herne Bay, was presented by Alr. Llerbert Nield, M.P., with the Roval Hlumane Society's medal. Sir William Bull, M.P., who presided, represented the Society. Mr. Nield also presented Miss Moss with a gold medal from “An Old Swimmer,’’? a silver medal from her swimming instructor, Mr. Bickett, and a gold wristlet from the Directors of the United Kingdom Picture Theatres, Limited. “ Mary Stuart’? is heading’ the bills for this week. ‘For the Crown’ and “The Girl of the Cabaret ’’ were two excellent dramas seen at the Theatre de Luxe last week. The management are showing © Robinson Crusoe’? and Ashes.” Kevstone and ‘ Pimple’? comics prove very popular. ‘ The Fire Fly? and “The Great Gold Robbery 7? were well received at the Kinema last week. An excellent orchestra has now been installed, and the musical renderings are of the highest order. —~-** David Coppertield 7’ is being featured this week, and showing four times daily.—-The programmes at the Broadway are of much merit and getting more popular week by week. “ Sevmour Ilicks and Ellaline Perriss ’ in latest dances, and ‘6 Motherhood or Politics ? are berng exclusively shown this week.— A onew manager has been appointed at the Hanwell Grand, and the programmes now consist of a greater number of short pictumnes.f-ohhe Acton Cinematograph how opens ts dears frery 3-tillhag paw. on Sundays.