Ysalwen looks up from a note she's been making on thermal transfer coefficients a second or two after Cullen's exhale.

Ah. He's found some books.

She turns back to her own work, a faint hint of tension singing across her shoulder blades.

Few of those books and sundries look like works about siege engines, you see.

And look, now she's mis-transcribed at least two variables in this equation, as well as several of the constants for materials of interest.

Maker take it!