Historical clue formulations

• Graduated — 2019-03-03
• Having an uninterrupted series of steps — 2019-02-16
• Having no direction, in math — 2014-01-05
• Ladderlike in arrangement — 2013-01-06
• Non-vector — 2009-02-11
• Like the reading on a thermometer — 2008-01-04
• Graduated — 2007-08-18
• Having an uninterrupted series of steps — 2007-05-15
• Graduated — 2000-08-20
• Like some variables — 2000-03-28
• Graduated — 1997-02-08
• Having magnitude only — 1996-09-29