|Inflating a Dog Screenplay
Chapter 19: The Mysteries of the Jet Pump Revealed (in which Peter learns a lesson in fluid dynamics)
by Eric Kraft
The screen rights are available.
|INT. ABOARD ARCINELLA, BELOW DECKS.
Patti is fastidious about touching anything greasy.
Peter recognizes the voice at once, turns and looks. Raskol is looking in through a porthole, grinning.Iíd better start bailing.PETER(sighs)Bailing is for chumps.RASKOL(through the porthole)
In another moment Raskol is down in the hold beside Peter and Patti. He has a couple of lengths of garden hose, and in his hand he holds a small metal device.
It is a length of tubing, threaded at both ends, with an opening at one side.If you knew enough about old boats to know what to pray for, this would be the answer to your prayers.RASKOL (CONTíD.)(showing the device)
Peter looks at it carefully.What is it?PETERItís a jet pump.RASKOL
Raskol goes to work. He connects a garden hose to either end of the jet pump. He runs one through the hatch and into the river. The other he attaches to a faucet on the dock. Then he turns the water on.It doesnít have any moving parts. How can it be a pump?PETERGive it here.RASKOL
He leads Patti and Peter onto the foredeck. He bends over and pulls the end of the other garden hose from the dark river. Water is rushing from it.Youíre putting her out of her misery?PETERNope. Iím bailing her out.RASKOL(soberly)By filling her up?PETERCome here.RASKOL
Below, he lifts the pump from the bilge and holds it so that the opening is just at the surface of the bilgewater. We can hear, and even see, the bilgewater being sucked into the opening and out into the river.Now come below.RASKOL (CONTíD.)(dropping it in again)
What a little sucker!PATTIThatís amazing! How does it work?PETERVery well.RASKOL(drily)But I mean, what makes it work?PETERI donít know. Itís one of the great mysteries of life.RASKOL
CUT TO:INT. ON THE SCREEN OF 1957 BLACK-AND-WHITE TV. The set of the ďSaturday ScienceĒ show. DOCTOR SCIENCE is a cross between Bozo the Clown and Albert Einstein.
Hey, kids! hereís the man with the atomic brain, Doctor Science!ANNOUNCERíS VOICEToday is fluid dynamics day!DOCTOR SCIENCE(wildly enthusiastic)(blows across a piece of paper, which rises)See that? The paper rises when I blow across it! Why the heck did that happen? Blowing lowered the pressure above the paper, and the greater pressure below the paper pushed it up. Thatís Bernoulliís principle!(a picture of Bernoulli)An airplaneís wing works the same way!
From one point of view, the wing is pushed up by the greater pressure below it, but from another point of view it is sucked up by the lower pressure above it. Both are valid explanations! .†.†. But perhaps you disagree. Perhaps you think Iím just ďplaying with words.Ē Ha! Take a look at this.(displays this apparatus)
I blow into this tube .†.†.(blows into left tube)The balloon inflates, of course.(allows it to deflate)Now .†.†. I suck on the other tube.(he does)And the balloon still inflates. So, sucking is the same as blowing!(shows a portrait of physicist G. B. Venturi)Enter G. B. Venturi, Italian physicist, who discovered that the speed of a fluid flowing through a tube could be accelerated by introducing a tapering constriction into the flow path. Wow!(an animated diagram)
Bernoulliís principle tells us that Venturiís constriction will lower the fluid pressure, since an increase in velocity must lead to a decrease in pressure, and thatís how a jet pump works! Water from an outside source enters under pressure. As it passes through the throat section, its velocity increases and its pressure decreases. Then, depending on your point of view, the lower pressure within the throat section sucks or the greater pressure outside the pump blows water from the bilge into the extractor inlet. Finally, the drive water and the bilge water shoot out the other side.Peter reaches out to the knob and turns the TV off. He has been watching this at home.
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Copyright © 2001 by Eric
The screenplay for Inflating a Dog is a work of fiction. The characters, incidents, dialogues, settings, and businesses portrayed in it are products of the authorís imagination and are not to be construed as real. Any resemblance to actual events or persons, living or dead, is entirely coincidental.
All rights reserved. No part of this teleplay may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the author.
The illustration at the top of the page is an adaptation of an illustration by Stewart Rouse that first appeared on the cover of the August 1931 issue of Modern Mechanics and Inventions. The boy at the controls of the aerocycle doesnít particularly resemble Peter Leroyóexcept, perhaps, for the smile.
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