if you've ever taken a flop or in a pool you don't feel like hitting something hard every good diver knows you must hit the water right or it won't get out of your way you must make your dive so's to cut the resistance just as a fish moves around without noticing the ocean we live near the bottom of a great ocean of air and although a hundred times thinner than water air has a force in motion air offers a lot of resistance to anything going through it our nature makes it possible for birds to fly through the air at speeds that seem out of proportion to the size of their muscles science has found that this bird speed is a matter of shape as well as strain the streamlines of birds make a little power go a long way with this in mind engineers study the resistance air offers to moving shapes since study of streamlines wind tunnels have been used to find out what happens when an object goes through the air a wind tunnel is simply a long tube with a fan or powerful blower at one end a stream of there is blown through the tunnel at vary of resistance or drag is measured by sensitive instruments in order to obtain a permanent record of resistance offered by various shapes liquid is used instead of a and its action recorded by a motion picture camera the panel will powered by a motor draws a liquid through the center passage and centered around the outer passages slots are used to eliminate whirls at the turns and create an area of even flow an object is placed in the liquid aluminum dust is that it so that we can see clearly what happens to the cur any form cuts through the liquid there's a good through air this shape is not streamlined as a liquid strikes the front door leading edge pressure is build up which causes resistance then as it is thrown into spins already which create a suction behind the body regardless of shape some resistance is unavoidable as the liquid goes by the shape its direction of fl changed and this change of direction waste power by rounding off the corners this change of direction is made more gradual so the amount of effort is decreased and resistance is cut down making the shape longer and thinner tends to cut down resistance this decreases the violence of the eddies and reduces the suction in the rear with an even thinner shade the liquid flows more easily and there are fewer  at the rear a streamlined shape with blunt nose and taper ring rear eases a hole with the least resistance and brings the liquid together at the rear with the least disturbance the ideal streamline follows a strict geometric design which engineers call  the length should be just about three times the greatest with that streamlining makes it easier for an object to get through the air by reducing wind resistance the higher the speed the more it helps any automobile travelling through the air meets a problem of wind resistance so engineers set about applying the principles of streamlining to the automobile and by rounding the contours and tapering the rear have smoothed out the flow of air around the body of the modern motor car and smoothed out eddies at the rear of course to a bird cars today mine seem already well streamlined but as seen by a worm the modern motor car is anything but streamlined yet the bottom of the motor car represents about twenty percent of the surface and sets up considerable wind resistance the development of more complete streamlining for motor cars will be the problem of engineers of tomorrow someday this problem will finally be solved sometime in the practical streamlining has been applied with success to the finest motor cars today with many additional advantages that streamlines of the new turret tower give greater strength to the body of the car than the old box like construction of yesterday the slanting windshields and windows cut down glare from rear insides and make safer driving streamlined fenders and close the wheels more completely and help to keep the car clean and they protect the wheels from force of strong winds making the steering easier sloping rear panels allow for more tire and luggage space these modern streamlines round out all details and absorb them into a good design with new beauty and dignity of appearance this practical streamlining brings to the new automobile increased covered by at convenience safety and beauty practical streamlining brings a modern motor car into step with modern air speed styling which has real economy and