EXPERIMENTAL STIDY OF HEAT LEAKAGE. 



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1°. Al, A2, A3, A4 refer to four axial-flow set-ups, all similar in 

 general respects to that shown in Fig. 1 and described in Section II, 1. 

 In all of these plugs, there are 37 holes 1^ inches long arranged in a 

 hexagonal pattern at each end of the soapstone block S; in plugs A2, 



Drop of Pressure, cr^ H<j 



Figure 11. Logarithmic plots of flow against pressure-drop. Abscissae, 

 pressure drops in cm. Hg. except for plug S, for which abscissae are one-half 

 of pressure drops in cm. Hg. Ordinates, flow in kgm. per hour. 



A3, A4, the diameter of each of these holes is 0.086 inch. In plug Al 

 the diameter of each hole is 0.076 inch. In plugs Al, A2 and A3, a 

 single piece of solid manganin wire having a diameter of 0.044 inch is 

 threaded through all 74 holes; in plug A4, this is replaced with a 

 stranded invar wire having ten strands, each of about 0.01 inch 

 diameter. The block S' is the same in plugs Al and A2, in which the 

 cross-channel is about \ inch in diameter and is located on the axis of 

 the block. The thickness of each of the blocks S and S' is about 

 two inches and the length of the cross-channel is about A^ inches. 



