Definition of "placidly"

We spent a lot of time up on the staging of the great furnaces, trying to pick up the tricks of the trade from the taciturn furnacemen who sat around placidly smoking, or chewing twist, and occasionally throwing in more pig iron to the molten white-hot metal.

1945 January and February, A Former Pupil, “Some Memories of Crewe Works—III”, in Railway Magazine, page 14

He was a big chubby man, in his middle thirties, the muscle of his rugger days now settling placidly to reminiscent fat.

1959, Anthony Burgess, Beds in the East (The Malayan Trilogy), published 1972, page 582