. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. alf an ounce, is suffici-ently accurate for this simple method of estimation. 46. Pressure Regulators.—To use two bottles of com-pressed gas in comfort, however, with only the one usual assistant, it was absolutelynecessary to deliver it tothe jets at approximatelyconstant pressure auto-matically. Many attemptswere vainly made in thisdirection, both in Englandand America. It is per-fectly easy to maintain aconstant pressure at theoutlet, whatever the pres-sure behind, so long as anoutflow is
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. alf an ounce, is suffici-ently accurate for this simple method of estimation. 46. Pressure Regulators.—To use two bottles of com-pressed gas in comfort, however, with only the one usual assistant, it was absolutelynecessary to deliver it tothe jets at approximatelyconstant pressure auto-matically. Many attemptswere vainly made in thisdirection, both in Englandand America. It is per-fectly easy to maintain aconstant pressure at theoutlet, whatever the pres-sure behind, so long as anoutflow is kept up unob-structed. But all earlycontrivances simply keptup a constant differenceof pressure between thetwo sides of the regulatingvalve, and directly theoutlet was turned off (asat the jet) the pressurerapidly accumulated be-hind till the rubber tubesblew off. It was necessary to contrive that when pressurethus began to accumulate, it should totally close the supplyfrom the cylinder, and take the strain off the frail rubbertubes. This has now been accomplished in several Fig. 50.—Beards Large Regulator Compressed gases 87 The first was invented by Mr. E. Beard, and is shown insection in fig. 50. It screws on to the cylinder at d, from whichthe small orifice is closed at d by the valve /. The gas liftsthis valve and enters the bellows a a, which rise with thepressure, but are weighted above to the pressure desired. Thetop of the bellows has a collar c1 screwed with a very longpitch, in which the screwed pillar f turns easily as the bellowsrises. Below the long-pitch screw f which is merely to turnthe pillar easily, is a slow-motion screw /, the turning ofwhich in its corresponding collar forces the valve down intoits seat and stops the supply: thus at a given pressure the
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
