774 TRUEBLOOD. 



In the block S' of plug A3, the cross-channel is located with its axis 

 on a line about l| inches from the lower face of the block. In other 

 respects, the block S' of A3 is similar to that of Al and A2. The 

 purpose of locating the cross-channel of A3 further from the lower face 

 of the block than in Al and A2 was to reduce the heat-leakage taking 

 place in the cross-channel. In the block S' of plug A4, the diameter 

 of the cross-channel is f inch, and it is located with its axis a little 

 above the axis of the block, which is otherwise similar to the blocks 

 used with the other plugs. By thus enlarging the area of the cross- 

 channel, the velocity of the steam while passing through it was made 

 practically the same as in the secondary superheater in the oil-bath. 



In plugs Al, A2 and A3, the lining in the tubes T and T' is of talc 

 having a radial thickness of | inch and an inside diameter of l\ inches. 

 In plug A4, this lining is of poplox of about the same thickness, and a 

 system of brass baffle plates separated by layers of copper gauze is 

 located in each passage just above the soapstone block S. Copper 

 baffles are also located in the chambers between blocks S and S'. 

 These chambers, in plugs A2 and A3, contain a few layers of copper 

 gauze, and in plug Al are empty. Xo baffling devices are located in 

 the talc-lined passages of tubes T and T' in any of the plugs Al, A2, A3. 



2°. VI and V2 refer to two radial-flow set-ups in the Y-type of 

 plug-case, illustrated in Fig. 3 and described in Section II, 2, b. VI 

 represents results with the plug case externally lagged with poplox 

 and wholly submerged in the oil bath, V2 results with the plug-case 

 directly immersed in the bath with no intervening lagging. The two 

 other arrangements used with this type of plug case ((ii) and (iii), 

 page 742) resulted in large heat-leaks, as might have been anticipated, 

 and are of no interest. 



3°, Ul and U2 refer to two radial flow set-ups in the U type of plug- 

 case, described in Section II, 2, c. These set-ups are similar in all 

 respects except that, with Ul, a copper gauze strainer was used in the 

 chamber M, Figs. 5 and 6, while with U2, an alundum strainer was 

 used. (Only one strainer was used with plugs Al, A2, A3, A4, VI, 

 V2, Ul and U2, there being no strainer corresponding to that shown 

 in chamber m, Figs. 5 and 6). 



4°. S refers to a radial-flow set-up of the straight-away type, 

 described in Section II, 2, d and illustrated in Figs. 4, 5 and 6. 



All the ju' vs. - plots (Figs. 12 and 13) represent least-square adjust- 

 ments of the observations. All the straight lines drawn on the — vs. 



