[Ulzgoroth]

I'm having difficulties quite early on, p11:
"A tiny mirror that deflects a beam of light replaces the pointer, for greatly increased sensitivity (treat as cutting edge; see p. 8)."

Both the second clause and the parenthetical are confusing. The description doesn't tell us anything about the increased sensitivity's effects unless reading telegraph signals is all that does. And while 'treat as cutting edge' is clear enough on its own the context suggests it should address the sensitivity, which it doesn't...