Old Wood and Rusty Iron   by Mike Creasy


 Screwed..... ​​ a feeling we've all had from time to time, whether looking at the restaurant receipt or thinking about what the nice salesman said. ​​ Feelings aside, the screw itself is actually a very useful thing, both for hanging up mirrors and for moving boats through the water. ​​ It seems that, back before the time of Christ, Archimedes drew up some plans for a screw-type water pump. ​​ And Archimedes may have borrowed the idea from some even earlier scientist. ​​ So why were early steamships driven by paddlewheels instead of screw propellers????

 One good reason is that, unlike the screw, paddlewheels had been in common use for centuries, even before Archimedes had his bright idea about the screw. ​​ Ancient Chinese and Roman civilizations used paddlewheels to drive everything from grist mills to trip hammers, making the wheel itself a standard part of the engineering scene. ​​ These were, of course, paddles driven by the passage of water rather than the other way around, but when steam began to make a source of driving energy available, it was only reasonable to connect a steam engine to a paddlewheel.