BRIDGMAN. — HIGH PRESSURE EXPERIMENTING. 



639 



the tube has a heavy thread cut on it, and is provided with a milled 

 •head, H, for a wrench. The packing is composed of three rings; a 

 thin ring of Bessemer, A, a ring of lead, B, jt of an inch square in cross 

 section, and a ring of Bessemer, C, 

 of yg i^ch square section. These 

 rings fit over the end of the tube in 

 an annular space ^e of an inch wide 

 between the tube and the walls of 

 the cylinder. On screwing up the 

 the tu})e, the rings are forced against 

 a conical shoulder, D, on the tube. 

 It will be noticed that the Bessemer 

 ring C supports the hydrostatic pres- 

 sure over the entire area of one face, 

 but that at the rear face there is a 

 vacant space, E, so that the pressure 

 must be balanced by the force exerted 

 by the cone on the corner of the ring. 

 This means that the intensity of pres- 

 sure in the steel at the corner is much 

 greater than the pressure in the liq- 

 uid, so that leak cannot occur. Here 

 again, we have the principle of a 

 packing with an unsupported area. 

 Tightness at the outside of the 

 Bessemer ring is secured by the 

 stretching of the ring over the cone. 



The lead washer merely serves the purpose of giving initial tightness, 

 and the thin Bessemer washer is to keep the lead washer in place. 

 The projecting ledge against which the washers bear opposite the cone 

 is shown in the figure as the rim of a nickel steel cup, F, resting loosely 

 in the hole. This construction is convenient, because it provides a 

 way of withdrawing the packing rings after use by inserting a threaded 

 rod through the bottom of the cup and pulling the cup out. It is, 

 however, quite possible to use part of the cylinder itself as the ledge, 

 since the removal of the washers, even without the de\'ice of the cup, 

 does not present serious difficulties. The lead ring and the heavy 

 Bessemer ring cannot be used more than once, but the thin Bessemer 

 ring for retaining the lead may be used several times. 



This packing has, at the date of writing, been in continuous use for 

 nearly a year, up to 13000 kgm. and 200°, without a single rupture or 



Figure 10. Detail of the final 

 packing of rings of soft steel for 

 the drilled tubing of nickel steel. 

 The scale of the diagram is f actual 

 size. 



