. Electric railway journal . ons of theruled straight lines were drawn through actual guaran-tees of the performance of a certain type of rotary pumpin which water jet action extracts the air; the upperline representing one pump and the lower line numerous plotted points all represent actual serv-ice performance of reciprocating dry-vacuum lesson from the plot is clear. If a reciprocatingpump is in fine condition it may be capable of re-moving a great amount of air from a condenser and yetmaintain admirably low absolute air pressure whileit is doing so. On the other hand, thr
. Electric railway journal . ons of theruled straight lines were drawn through actual guaran-tees of the performance of a certain type of rotary pumpin which water jet action extracts the air; the upperline representing one pump and the lower line numerous plotted points all represent actual serv-ice performance of reciprocating dry-vacuum lesson from the plot is clear. If a reciprocatingpump is in fine condition it may be capable of re-moving a great amount of air from a condenser and yetmaintain admirably low absolute air pressure whileit is doing so. On the other hand, through neglectof skillful maintenance work the absolute pressure maynot be notably low even though the air leaking into thecondenser and needing to be removed by the pump maybe moderate in amount, thanks to a tight condenser. The use of an air bell gives such powerful meansof control of vacuum maintenance by putting air leak-age measurement upon a quantitative basis that anillustration of such a bell may be of interest, and is. FIG. 4—AIR BELL FOR MEASURINGAIR LEAKAGE October 19, 1918 Clear the Track for Berlin 697 accordingly shown in Fig. 4. An air bell made fromthis drawing has been in satisfactory service for sev-eral years. The conception of using such a bell forthe purpose did not originate with the company withwhich the writer is connected. So far as he knows itwas first used by the New York Edison Company. As a refinement in the use of an air bell, a hole maybe drilled in the top of it and a rubber stopper insertedthrough which is passed an ordinary chemical ther-mometer. In this way the temperature of the air maybe measured as the bell rises. This allows correctionof the air volume to standard temperature to be made. Relative Life of Manganese and Open-Hearth Rail on Curves Results of Tests Are Given Showing ManganeseRail to Wear About Seven Times as Longas Open Hearth By H. W. Roberts Assistant Engineer of Maintenance of Way,Elevated Railroads of Chicago THE accompany
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