. Cassier's magazine . s been describedas an instrument which bearsto the work of the engineerthe same relation which the stetho-scope does to the physician. It isconceded to be absolutely necessaryto the operating engineer, and itsvalue can hardly be overestimated. The indicator diagram furnishes theonly known means for ascertaining theaction of the steam in the cylinderof an engine, enabling its efficiencyto be determined and the internalwastes detected. Under such cir-cumstances it is of vital importance that the accuracy of the instrumentbe unquestioned, and any suspicionof inaccuracy in t
. Cassier's magazine . s been describedas an instrument which bearsto the work of the engineerthe same relation which the stetho-scope does to the physician. It isconceded to be absolutely necessaryto the operating engineer, and itsvalue can hardly be overestimated. The indicator diagram furnishes theonly known means for ascertaining theaction of the steam in the cylinderof an engine, enabling its efficiencyto be determined and the internalwastes detected. Under such cir-cumstances it is of vital importance that the accuracy of the instrumentbe unquestioned, and any suspicionof inaccuracy in the indicator castssuspicion upon all the diagramswhich have been made by it. Since the indicator is really a spe-cial form of recording pressuregauge, it is evident that the springby which the varying pressures inthe cylinder are measured must beentirely reliable and correct. Whileevery care is taken in the originalproduction of the springs used forthis purpose, the only method to beassured of their accuracy is to sub-. INDICATOR TESTING APPARATUS. 90 INDICATOR TESTING 91 ject them to test in the completed in-strument. A special apparatus for testing in-dicator springs has been designedand is made by the Schaefler &Budenberg Manufacturing Company,of Brooklyn, N. Y., the general ar-rangement of which is shown in theillustration. The principle uponwhich this apparatus is made is thatof weighing the pressure upon a pis-ton of known area, employing accu-rate scale beams instead of springs,and thus furnishing a thoroughlyscientific basis for comparison andcalibration. The testing apparatus consists es-sentially of a closed vessel of castiron, capable of resisting internalpressures up to 200 pounds persquare inch. To this chamber thereis fitted a cylinder containing a pis-ton of precisely one-half a squareinch in area, the piston being free tomove vertically in the cylinder. Thelower portion of the piston is pointed,and rests in a yoke, which is sus-pended on the knife edge of a scal
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyork, booksubjec
