Leap-year or bissextile is every fourth year, and so called from its leaping a day more that year than in a common year: so that the common year hath 365 days, but the leap-year 366; and then February hath 29 days, which in common years hath but 28. To find the leap-year you have this rule:
Divide by 4; what's left shall be
For leap-year 0, for past 1, 2, 3. Harris.
That the sun consisteth of 365 days and almost six hours, wanting eleven minutes; which six hours omitted will, in process of time, largely deprave the compute; and this is the occasion of the bissextile or leap-year. Brown's Vulg. Err.