The following list gives the colours, and the various uses for them. They have already been used in the foregoing pages to distinguish the various regions of the Tessaract, and the different individual cubes or Tessaracts in a block. The other use suggested in the last column of the list has not been discussed; but it is believed that it may afford great aid to the mind in amassing, handling, and retaining the quantities of formulae requisite in scientific training and work. _Region of _Tessaract _Colour._ Tessaract._ in 81 Set._ _Symbol._ Black Syce Plebs 0 White Mel Mora 1 Vermilion Alvus Uncus 2 Orange Cuspis Moles 3 Light-yellow Murex Cortis 4 Bright-green Lappa Penates 5 Bright-blue Iter Oliva 6 Light-grey Lares Tigris 7 Indian-red Crux Orcus 8 Yellow-ochre Sal Testudo 9 Buff Cista Sector + (plus) Wood Tessaract Tessara - (minus) Brown-green Tholus Troja ± (plus or minus) Sage-green Margo Lacerta × (multiplied by) Reddish Callis Tibicen ÷ (divided by) Chocolate Velum Sacerdos = (equal to) French-grey Far Scena ≠ (not equal to) Brown Arctos Ostrum > (greater than) Dark-slate Daps Aer < (less than) Dun Portica Clipeus ∶ } signs Orange-vermilion Talus Portio ∷ } of proportion Stone Ops Thyrsus · (decimal point) Quaker-green Felis Axis ∟ (factorial) Leaden Semita Merces ∥ (parallel) Dull-green Mappa Vulcan ∦ (not parallel) Indigo Lixa Postis π⁄2 (90°) (at right angles) Dull-blue Pagus Verbum log. base 10 Dark-purple Mensura Nepos sin. (sine) Pale-pink Vena Tabula cos. (cosine) Dark-blue Moena Bidens tan. (tangent) Earthen Mugil Angusta ∞ (infinity) Blue Dos Frenum a Terracotta Crus Remus b Oak Idus Domitor c Yellow Pagina Cardo d Green Bucina Ala e Rose Olla Limen f Emerald Orsa Ara g Red Olus Mars h Sea-green Libera Pluma i Salmon Tela Glans j