Chambers's encyclopædia; a dictionary of universal knowledge . glazed or not. Large projectionsj form an obstacle; but mere roughness of surfacej is filled up by an adhering film of water, which isi as good as a glaze. The resistance increases greatlyj with the narrowness of the pipes. Engineers haveI formulas, deduced in great part from experiment,for calculating the discharge through pipes of givenlength and diameter, and with a given head; butthe subject is too complicated for introduction water flowed in a conduit pipe without frictionor other obstruction, so that its velocitj were
Chambers's encyclopædia; a dictionary of universal knowledge . glazed or not. Large projectionsj form an obstacle; but mere roughness of surfacej is filled up by an adhering film of water, which isi as good as a glaze. The resistance increases greatlyj with the narrowness of the pipes. Engineers haveI formulas, deduced in great part from experiment,for calculating the discharge through pipes of givenlength and diameter, and with a given head; butthe subject is too complicated for introduction water flowed in a conduit pipe without frictionor other obstruction, so that its velocitj werealwajs equal to that due to the head of water,there would be no lateral or bursting pressure ortthe walls of the pipe ; and if the pipe were i^ierced,the water would not squirt out. Accordingly, vritha short tube or adjutage, which, instead of obstruct-ing, increases the flow, there is not only no lateraloutward pressure on the walls of the tube, but thereis actuall\ a pressure inwards. If a hole is madein the wall of a cylindrical adjutage, A (tig. 2), and. Fig- 2. the one end of a small bent tube, be, is insertedin the hole, while its other end is dipped in a vesselof water, T, the water wiU be sucked up the tube,shewing the tendency that the adjutage has to forma vacuiun. But when the velocity of discharge isdiminished by the friction of a long pipe, or byany naiTowing, bending, or other obstruction in thepipe, then that portion of the pressure of the headof water that is not carried off in the discharge,becomes a bursting pressure on the walls of thepipe. This pressure is imequal at different parts ofthe pipe. At the end e, where the water issues freeand unobstructed, it is next to nothing, and gradu-ally increases towards the reservoir at d, where itis equal to the difference between the head of waterin the cistern, and the head due to the velocityvrith. which the water is actually flowing in thepipe. The principle now explained accounts forthe fact, that pipes often biu-
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Keywords: ., bookcentury1800, bookdecade1860, bookpublisherlondo, bookyear1868
