Speculations about "fourth spatial dimension" were quite common in the time of Wells (almost as now). The Idea to put time to the same coordinate system as spatial coordinates was obvious and trivial if not for Euclid then for Descartes for sure (remember those school graphs of distance vs time). What stated Wells is "look, they are similar: all are measurable. If we can change our coordinate in space maybe with some device we can arbitrarily change our time coordinate". What came from Einstein's mathematics is: "time and space positions are not independent values but mixed up in a special way". I don't see why it can be the same.
I am sorry but I cannot agree with you. What Wells really said was: "There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it". It's a citation from the book. So he didn't say about putting time in the same coordinate system as space, he really introduced the idea that time is just another dimension of space.
On the other hand Minkovsky and Einstein haven't just showed that "time and space positions are not independent values but mixed up in a special way", because that was very obvious much earlier. Actually if the time and space coordinates had not been dependent on each other, the world would have become a chaos, for the mutual positioning of objects in space at certain moments of time could have been impossible. No, what Minkovsky and Einstein really invented was the assertion that time and space not just depend on each other, but that they are unity, they are 4 sides of the same physical phenomenon.