I picked up this novel's predecessor, Mainspring, after enjoying the "50s-style sf alien encounter with added Nazis/gangsters" that was Rocket science and a string of strong short stories (On the human plain, Last plane to heaven: a love story, Human error, The sky that wraps the world round, past the blue and into the black) that were evidence of a highly imaginative writer who could adopt different styles and modes with aplomb.
Imaginative certainly applies in spades to this series. The Earth and the other celestial bodies follow visible geared "tracks" through the solar system, with the connection points being at their equators. On Earth the equatorial track is an enormous uncrossable 'Wall' and divides the north and south hemispheres. The northern hemisphere is geographically identical to our Earth, but has a 19th century-level civilisation which is controlled by two mighty empires, British and Chinese, using flying ships and submarines in an alternate-world built around steampunk technologies. What lies in the southern hemisphere is unknown. Because the "machinery of existence" is so obvious, religion is powerful but changed: for Christians, for example, their 'Christ' died on a Wheel, not a Cross.
In Mainspring, Hathor, a lowly apprentice, is given a quest by an angel to find a 'Key' and rewind the 'Mainspring' of the world. Overcoming all sorts of opposition, from jealous, powerful rivals to a potpourri of strange creatures and landscapes, he achieves his quest. Hathor is absent from 'Escapement'. Its main characters are Yale University librarian Emily Childress and Chief Angus al-Wazir from the airship Bassett (both of whom appear in Mainspring), and Boaz the Brass Man (a robot), and Paolina Barthes, a child prodigy, who lives on the Wall itself. All these characters trace paths that eventually cross, and these paths illuminate more of Lake's strange clockwork universe.
As well as the clash of Empires, there is a struggle between two global secret societies who have different views on how to approach their strange world, either to accept it as it is, or try to control it. The two northern Empires, having reached a stalemate, are tring to find a way into the southern hemisphere, the British by means of a giant tunnelling engine, the Chinese via the excavation of old ruins of a city near Singapore, seeking lost knowledge. Paolina is sought by all these factions, as with a device she self-builds called a 'gleam', she can manipulate the workings of the world directly. Originally wanting to escape, she realises how wrong her view of things is: she wants freedom and wisdom but finds both where she least expects. Childress has to impersonate a 'Mask', a high-up in one of the secret societies, but achieves more by being herself. Chief Angus al-Wazir is an agent of the Queen but eventually realises that there are deeper loyalties. The most interesting character is Boaz, who seems to be an emergent AI from a machine civilisation. He is also from the Wall, which seems to house a multitude of races and wonders, like winged people that attack the British drilling expedition and an underground rail system that runs around the equator!
It is the sheer invention displayed that I think makes this novel worth reading. I wonder how all these ideas, threads and characters will converge and work out in 'Pinion' which recently came out in hardback.