=29. RECEDAT= (_TM2_) is no doubt a scribal conjecture, but a correct one: 'Why, in case disaster should strike ...'. Most manuscripts have RECEDIT.
=31. ORBE= probably means 'wheel'; compare Tib I v 70 'uersatur celeri Fors leuis orbe _rotae_' and _Cons ad Liuiam_ 51-52 (quoted in the next note). However, Professor E. Fantham points out to me that it could also mean 'sphere': she cites Pacuvius 366-67 Ribbeck2 (_Rhet Her_ II 36) 'Fortunam insanam esse et caecam et brutam perhibent philosophi, / _saxoque_ instare in _globoso_ praedicant _uolubilei_'. Smith at Tib I v 70 gives numerous instances of both images.
=32. QVEM=, found in Heinsius' _fragmentum Boxhornianum_ (=Leid. Bibl. Publ. 180 G), must be right as against the QVAE of the other manuscripts; if a definition is to be given after the preceding 'haec dea non stabili quam sit leuis orbe fatetur', it should be a definition of the wheel, not the goddess. But the resulting _quem summum dubio_ seems very awkwardly phrased, and further emendation is probably needed.
The obvious solution would be to read 'quem summo [_C_ in fact reads _summo_] _dubium_ sub pede semper habet'. This would give _orbis_ a standard epithet, as at _Tr_ V viii 7-8 'nec metuis _dubio_ Fortunae stantis in _orbe_ / numen' and _Cons ad Liuiam_ 51-52 'nempe per hos etiam Fortunae iniuria mores / regnat et _incerta_ est hic quoque nixa _rota_'. In support of the rather more difficult _summo ... pede_ (='toes') Professor R. J. Tarrant cites Sen _Suas_ II 17 'insistens _summis digitis_ ['toes']--sic enim solebat quo grandior fieret', Sen _Tro_ 1090-91 'in cacumine / erecta _summos_ [_uar_ summo] turba librauit _pedes_', and _Met_ IV 562 'aequora destringunt _summis_ Ismenides _alis_'; compare as well _Met_ IX 342-43 'in adludentibus undis / _summa pedum_ taloque tenus uestigia tingit'.
A second solution might be to read 'quem _dubio summum_ sub pede semper habet'; the transfer of _dubius_ from _orbis_ to _pes_ seems acceptable enough, and _Met_ IV 134-36 'oraque buxo / pallidiora gerens exhorruit aequoris instar, / quod tremit exigua cum summum stringitur aura' offers a good parallel to _summum_.
The image of Fortune standing on her wheel occurs elsewhere in Ovid's poems of exile at _Tr_ V viii 7-8 (quoted above) and _EP_ II iii 55-56 'scilicet indignum, iuuenis carissime, ducis / te fieri comitem stantis in orbe deae'.