HELIUM was discovered in 1868; Helium is relatively rare, so using it to fill balloons seems counter productive. :D
It does have many medical and scientific uses though, the largest being in cryogenics! Also used for MRI magnets, in computers and in air bags, and in many other ways is vital. I mean, how else would we make our voices all squeaky?
This flatty is under the fallen tree, on the stump below it.