Twentieth century hand-book for steam engineers and electricians with questions and answers; a practical non-technical treatise .. (1913)
Swingle, Calvin Franklin, 1846- [from old catalog] · Chicago, F. J. Drake & company · leaf 347
f the ordinary U-tube has been replaced by a tubeslightly inclined to the horizontal^ as shown in Fig. 108.By this arrangement any vertical motion in the left handupright tube causes a very much greater travel of theliquid in the inclined tube^ thus permitting extremelysmall variation in the draft… … Fig. 108ellisons draft gauge outline it) until its meniscus rests at the zero point on the right.The left hand leg is then connected to the source of draftby means of a piece of rubber tubing. Under these cir-cumstances, a rise of level of one inch in the left handvertical tube causes the meniscus…
