I also discovered this one recently. It's certainly regarded as New Zealand's first work of science fiction and does indeed have steampunk elements. The principal mode of travel between countries is by airship (but they're called something else - I wish I could remember where I left my memory).
I enjoyed it. It's not a heavy read by any means. The OCR job to get it into e-reader format isn't perfect , but they seldom are.
In honour of Sir Julius,
New Zealand's awards for SF/fantasy/horror works (the 2015 awards were announced this Easter weekend) are named for him.