1. Harley MS 321, f 28v (item 2) Reference (shelfmark): Harley MS 321, f 28v (item 2) Title: Tractatus de sphera Scope & Content: Rubric: 'Tractatus de sphera'; incipit: 'De causis eclipsil sol et lune.' Collection Area: Western Manuscripts Languages: Latin Date Range: 1st quarter of the 15th century Extent: 1 folio.