782 



TRUEBLOOD. 



less rapidly as the pressure-di'op is raised. The general trend of these 

 plots as compared with that of the line representing the true value of /x 



20 



40 



60 80 



Drop of Pressure, cm Hg 



Figure 15. Temperature drop v.s. pressure drop, axial flow plugs. The 

 numbers adjoining the plotted points indicate the number of runs involved. 

 The numbers along the axis of ordinates are for plug A4, the curves being 

 spaced at intervals of 1° to avoid confusion. The straight dotted lines have 

 slopes equal to the extrapolated p. for plug S. 



illustrates, probably better than anything else, the general hopeless- 

 ness of attempting to obtain reliable values of /x with such apparatus 

 as this. 'The AT" vs. Ap plot for plug A3 shows smaller heat-leakage 



