. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . in the train as kinetic energy. Grade hasa similar effect, and the force indicated by the dynamometermay be greater or less than that required at the given velocityon a level by the force which is derived from, or is turned into^potential energy. The effect of curvature should be eliminatedby subtracting from the dynamometer record to poundper ton per degree of curve, according to the rules for compen-sation
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . in the train as kinetic energy. Grade hasa similar effect, and the force indicated by the dynamometermay be greater or less than that required at the given velocityon a level by the force which is derived from, or is turned into^potential energy. The effect of curvature should be eliminatedby subtracting from the dynamometer record to poundper ton per degree of curve, according to the rules for compen-sation of curvature as developed in § 511. Correct for gradeby subtracting from the dynamometer record twenty poundsper ton for each percent of grade, assuming that the test trainis moving up a grade; if the train is moving down grade, adda similar amount. Add (or subtract) the effect of change invelocity, as computed in § 435. Usually each dynamometerobservation will need to be corrected by one or all of these cor-rections in order to determine what would have been the resist-ance on a straight, level track, at some definite uniform velocity. 482 RAILROAD CONSTRUCTION. § ci ■g 3& ^0 30 40 50 60Average veeighfe per car-tons 70 -ioi 1908-09 the Railway Eng. Dept of the Univ. of Illinoisconducted a series of tests, under the direction of Prof. E. ,* which were so elaborate and thorough that theydefinitely demonstrated that (a) the resistance per ton of anycar depends very considerably upon the weight of the car, whichis graphically shown in Fig. 206 a, and (b) the actual resist-ance per ton is variable and uncertain, and therefore no formula or resistance curve can assumeto represent such resistancewith a close percentage of ac-curacy. This uncertainty isillustrated by the fact that, inspite of the most elaboratetare to eliminate all observa-tional error and obtain uniformresults, one typical group ofplotted points had an averagedeviation of about 8% fromthe curve of
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
