DOES WATER RUN UPHILL?

Grey River Argus, 24 February 1927, Page 8

DOES WATER RUN UPHILL?

(To the Editor). Riir, —Your correspondent “Archimedes, ” makes an interesting endeavour, under the above heading, to reverse the entire science of dynamics, which teaches as an indubitable fact that water always flows, or tends to flow, from a higher to a lower level i.e., from a greater to a lesser distance from the earth’s centre; and that capillary attraction, centrifugal force etc., but modify this gravitational effect. The sibelling of the equatorial waters represents a compromise between gravitational and centrifugal force as does, likewise, the vast slope of land “'that rises towards the equator a perpendicular distance of thirteen miles.’’ It is the equilibrium between the just-named forces that keeps the earth its present shape. It can be shown (1) that a planet of any size cannot be other than globular; (2) that it is rotational velocity that makes an equatorial protuberance possible and that, consequently, the earth, if it ceased to spin, would immediately change from an oblate spheroid to a perfect sphere. Gravity moves, or tends to move, matter in a direction which points to the earth’s centre. Bodies “fall” as we say. Weight, a measure of this falling tendency, decreases above the surface in the same rates as the square of the distance from the centre increases. Moved to the pole from the equator, the weight of a body is augmented by .001761: due solely to its thus being brought nearer, by thirteen miles, t.<? the centre of the globe; and by .00346: due alone to axial rotation, which produces a force opposite to that of graviety and called therefore ‘ ‘ centri fugal” (Latin, centrum a centre, and fugio, to flee). Greatest at the equator, where the rotational velocity is 1522 feet per second, the centrifugal force progressively diminishes till it is nothing at the poles, where the rotational velocity is, likewise, nil. Put to deduce from the lighter weight of masses at the equator, that they there tend to move, not to, but, from the earth, is to picture the action of only the smaller force; or to regard it as does Archimedes, as the larger. And very much the same criticism applies, I suspect, to the proposition that equatorial waters run uphill. Water tends downwards and only minutely less so at the equator than elsewhere; and “Archimedes’s” assertion that its predominating movement is upwards and outwards, is apparently but an ill-based physical dogma of his own. If the centrifugal force were the greater as he affirms bodies would fly of at a tangent to the terrestrial circumference and our planet as a whole be disrupted Your correspondent fails adequately to answer the query, Why does water betimes run uphill? He merely tells the querist something that isn't true viz., that it is the exception for it to run down hill. Very likely, an undulating pipe line suggested the problem to the querist in the first instance. Somewhere about 1643, Torricelli observed that a jet of water rose almost to the height of the level of the water in the reservoir from which it was supplied. He found, that, is, that water could be made to run uphill for nearly the same vortical distance as it ran down. From this, ho drew important mathematical I inferences, -which have since been amply \ erifled. Through a frictionless pipe, could one be constructed, a jet would mount, not approximately, but exactly, to the height of the surface of the reservoir water. Observations, such as Torricelli’s, demonstrate that water, unless driven by mechanical means, or unless it has its state changed by heat, Can move upwards at a given point, or points, only when at some other point it has moved a greater perpendicular distance downwards. Tire theoretic “head” from which water must fall to have engendered in it a stated velocity, is given by squaring the latter and dividing it by 2 g; where g equals the velocity imparted, per second, by the force of gravity, to a freely falling body. Water at rest and at a certain head, is said to possess potential eno 'gy and water in motion is said to possess Kinetic energy. One of the epoc'ir' achievements of ISih century physic

was the formulation of the law knoo as the conservation or equivalence oi 1 energy. This law postulates, inter alia I that energy is never destroyed but onlj I changed from one form to another; acid that among such possible changes v that of kinetic into potential energy. 1 and vice versa. The flowing of wa’.cr I uphill is one illustration of the law. In the first place, the water, by virtue of Its head, possesses potential energy, and, in the second, by virtue of its flow down hill kinetic energy, and in the third, by virtue or Its flow uphill, has again potential energy confer) cd upon it. The change here is front P to K typo of energy, and from K type back to P. The down-and-up flow of the water is, in fact, dynamically similar to the swing of a pendulum. Though tlw conditions governing the flow of water in pipes are not altogether the same as those governing its flow in op«n channels, still, the same basic principles apply to both esses. The average slope of continental rivers is about two feet per mile, so that a river 909 miles long would represent a vertical fall of 1800 feet. Most of the great equatorial streams rise in vast mountain ranges towering ' miles in height. The continents are each traversed by an axis from-which the ground slopes on either side to the sea. This ixis is not necessarily identical with the highest parts of the land; these may rise now to one side of it, now to the other; bttt it is the line of average greatest elevation, as is manifested by the way in which the rivers flow from each side of it. Nor is the axis placed along the centre of the continent, more usually it is situated much on one side. A river flows towards the equator when its course as a whole inclines towards its. Rivers arc to an enormous extent deprived of flow by J the friction of their beds. In uniting fwo streams may occupy a channel no broader, than nor as broad as one of them did before; and, with like declivity the combined stream runs faster; for the same volume of water has tow to overcome the friction of only

5 one channel instead of two. eighteen i hundred miles above its mouth tto • Mississippi is 5000 feet wide; but where t if enters the gulf its width is only 2470 ' feet, or about half, and that after it, bas been fed by streams so vast as the ; Missouri, Ohio, Argansas and Red Rvers. Through this comparatively narrow channel passes out to sea the drainage of nearly half a continent! a river may acquire sufficient velocity We thus perceive one way in which to carry it up an incline plane forming part of its bed. That all the energy in the solar system is derived from the sun is one of the fundamental teachings of physical science. ’ Water from the oceans, seas and lakes is vapourised by the heat of our luminary, and in this state blown by winds, which are also an effect of solar energy, over wide areas and’ ultimately precipitated in the form, mainly, of rain and snow. Of the total water thus precipitated on the irregular land, part is re-evaporat-ed; part Hows off as surface water, more or less rapidly and more or less directly, to the ocean, and part sinks into the ground. A portion of this last is by the force of capillary attraction, retained within reach of the rootlets of vegetation; the balance percolates downwards till it reaches the level of the underground flow, joining this in a relatively slow movement, either to some nearby lake stream or other [drainage, course, or directly to the sea. Thus does the solar heat, working : against the force of gravity, elevate water, placing it in relation to that force, in a position of advantage, and thus does every shower of rain and

every stream transmute so much, of the total potential into kinetic energy. Kijietie energy of every kind is finally re-converted into heat, which is ab sorbed by the other and lost to our system. There is accordingly going on throughout, the uni verst- a perpetual dissipation of motion, accompanied by a perpetual contraction of matter, which in the course of aeons will bring universal death. 1 am etc., BRAMAH.