old ideas ->new tech

I have been wondering for a while now about what old inventions that possibly failed when first invented due to the materials at the time being unsuitable would now be possible to make and get working? a while back on uk tv there was a programme that showed someone building a variation of da vinci's aircraft and with a few mods managed to get it to fly. Anyone else have any thoughts on this?

I know that when lasers and masers were first discovered and developed they were described as a "solution without a problem" as although they were great new tech there were no practical uses for them.

This of course has changed and lasers are now used in a variety of applications in the home and scientifically, mainly because other new developments have been developed around laser technology such as CDs and DVDs.

I believe there are many old technologies waiting to be re-investigated....like solidshot said, look at some of di vinci's work, alot of that could be re-done. Also many people from the past would have created things on paper and then just left them. So yea I believe there is a lot out there waiting to be re-rediscovered, or at least used to push us in the right direction.