[x3iv130f]

In the earliest iterations Tolkien imagined Middle-Earth to have steam punk technology. I believe it is because steam ships and rolling tanks are much closer to what Tolkien expierenced in the First World War when he first conceived his world.

I suspect over the course of his life Tolkien became more and more frustrated with technology, and removed most overt traces of it to bring his stories closer to what he read in Medieval folk lore.