The Dynasphere! Your Questions Answered. A Legacy Appraised.

Doctor Purves, inventor of the Dynasphere... Wait, is that a three-foot-wide blind-spot directly in front of the driver?
 Define "spot".
But how do you see where you're going? 
 Leaning out the side is best on any terrain upon which one might encounter an obstacle, certainly.
All terrain, then?
 By no means.
On what terrain might one not encounter an obstacle?
 A race course.
What?
 Unless there's a race happening on it, obviously.
And what does the steering wheel do? 
  It tilts the vehicle. 
It doesn't steer the vehicle?
 Oh. Doesn't it?
Is tilting a vehicle the same thing as steering it?
 I thought... Let me just... Oh. Okay. I thought it was the same thing.
So how do you actually steer the vehicle?
 Actually, I won't lie, there currently exists no footage of the Dynasphere doing anything other than traveling in a - Look, my wife's really a lot better at explaining all this...

What was that?
 What?
What did she mean, gravity itself is our motive power?
 Ah well, the actual design for "Jumbo" is based on sketches by Leonardo Da Vinci for a perpetual motion machine?
Really?
 Yes. Look.

But doesn't the Dynasphere have a two-cylinder, air-cooled Douglas engine with three speed gear box?
 Is that what that noise was?
Goodbye.
 Goodbye. 

Epilogue: J.A. Purves may not have cracked perpetual motion, or steering, or seeing out of the front of a vehicle, but that hasn't stop others trying. And now, with the invention of 3D printers, Da Vinci's dream of eternally renewable energy can finally be realised. Behold! (Really, I know it's nearly ten minutes long, but I love this video so much. Apparently it's all about the neodyanium magnets...)

 The "link in description box" is here. There are lots of great Dynasphere images, real and imagined, including the Popular Science cover, here. Wikipedia obviously has an entry on it here. And I have no idea if that was actually his wife. Apologies.