636 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Figure 8 is useful. It will be seen that this is an application of the 

 packing principle described above. Here the projecting pipe itself 

 is the area unsupported, so that the rubber packing, A, exerts its 

 pressure on an area less than that acted on by the liquid by an amount 

 equal to the area of the cross section of the pipe. Brass washers, 

 B and C, are strong enough for the end of the tube. These brass 

 washers should fit the hole within one or two thousandths of an inch. 



Fig. 8. 



Fig. 7. 



Figure 7. Coned coupling for copper tubing up to 1000 kgm. The scale 

 of the diagram is i actual size. 



Figure 8. The packing for copper tubing, or, with slight modifications, for 

 commercial steel tubing up to 4000 kgm. The scale of the diagram is f actual 



so that the rubber may not be blown through the cracks. Occasion- 

 ally, after several years' use, a copper tube may fail by the " pinching- 

 off " effect at the rubber packing. 



For pressures higher than 1000, up to 6000 or 7000 kgm., it is pos- 

 sible to get commercial steel tubing. The National Tubing Co., Pitts- 

 burg, Pa., draws a size of "Shelby" tubing Ye of an inch outside 

 diameter, and j^ of an inch inside diameter, which I have found suit- 



