imperturbable

In the meanwhile, Sir Piercie Shafton sate still as a stone on the chair in which he had deposited himself, […] his eyes cast up to the ceiling as if he had meant to count every me…

[T]he good Dominie bore all his disasters with gravity and serenity equally imperturbable. "Prodi-gi-ous!" was the only ejaculation they ever extorted from the much-enduring man.