Grocott & Ward, comps. Grocott’s Familiar Quotations, 6th ed. 189-?.

Whistle

Hear the shrill whistle, which doth order give
To sounds confus’d.
Shakespeare.—King Henry V., Chorus to Act III.

Their whistling noise made the birds aghast.
Shelley.—The Sensitive Plant.

He trudg’d along, unknowing what he sought,
And whistled as he went, for want of thought.
Dryden.—Cymon and Iphigenia.