Sir Francis Darwin,
Springtime and Other Essays
“ It is illustrated in an Anglo-Saxon Psalter of the early eleventh century, which is preserved in the Cambridge University Library. The whistle which we have all made in our childhood by removing a tube of bark from a branch in which the sap is rising, is an advance on the panpipes, since it includes a method of producing a thin stream of air which impinges on a sharp edge, whereas in the panpipes we depend on our lips for the stream of air. ”
