content: Like the early steam engines, there were a huge amount of engine designs created, but it wasn't until boiler technology caught up did we start to see successful applications.   As you pointed out its all just giving it a go until someone gets it right.  Also, it helps to understand that without some of the earlier advances in steam technology it may have been a lot harder or even inconceivable to build the first functioning boiler. After all, how does one design something effectively, without a good understanding of why it is needed to do the job it is being designed for.  I'd call that a startup product, art or just plain old junk. With that said though, all those things carry the potential to be re-purposed for things that were at the time, outside of the scope/understanding of the person who originally designed and built that thing. All the best, peace...