| http://www.w3.org/ns/prov#value | - In the form shown in Fig. 3, the stuffing box 42 has been modified over that shown in Fig. 1 so that instead of theconical surface l8 there is a V-shaped groove 43 into which is fitted a cor-' respondingly V-shaped ring 44 made of suitable flexible material such as rubber, either synthetic or natural, leather, or the like.
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