Midnight Mark
Goes into the Winding Key and the Dead Dial of the Great Pendulum; two different marks play the Hour Check at the Desk. Its hour is the dead of night. Hold the Loupe up to the open sky at that hour with a sheet of paper in your inventory; each mark is written once a day. Once you have one, copy it at the Flux Workbench: the mark over a sheet of paper — the mark itself stays.
kinditemcreative tabFluxion
Currents
Gloom2
Tempo2What the Loupe reads: 4 in all. Wheel of Currents
In the Codex
Entry 
Hour Marks — Reveal Tempo and Gleam with the Loupe and solve the puzzle at the Desk — the Loupe will learn to catch the hour in the sky.
Where to get
Deeds in the World
Hold the Loupe up to the open sky at its hour, with papereach mark once a day, after the "Hour Marks" entry