chapter thirteen the edge of the envelope in which we learn the theory of baize-space - devious collabone - the grand trunk burns - so sharp you 'll cut yourself- finding miss dearheart - a theory of disguise - igor moveth on - 'let this moment never end ' - a brush with the trunk - the big sail unfurls - the message is received mustrum ridcully , archchancellor of unseen university , levelled his cue and took careful aim .