Delta-T is the difference between Terrestrial Time and Universal Time. Terrestrial Time or Dynamical Time is a function of Earth’s orbital motion. Universal time is a function of Earth’s spin motion. Earth’s spin motion experiences a secular lengthening due to tidal drag exerted by our Moon, it experiences periodic variation due to Saros Period (an interval of 18 years and 111/3 days after which the Earth, Moon and Sun return to nearly the same relative positions and cycle of lunar and solar eclipses begin to repeat itself), Earth’s spin motion experiences periodic variation due to sidereal period of Moon, due to Spring and Neap tide. Periodic variations in Earth’s spin take place due to seasonal changes also. Earth’s spin motion experience irregular variation due to geophysical and geological factors such as plate tectonics, setting of an Ice-Age, thawing of ice-age, ocean currents and global wind patterns interacting with mountain ranges and electromagnetic coupling between core and mantle. UT1 or Universal Time is counted from 0 hour- 0 minute- 0 second midnight on 1/01/1900 is measured in terms of spin period. Over long term the periodic and irregular variations will average out but secular lengthening of the length of the day will continue as a result UT1 will fall behind the dynamical time. When UT1 falls behind TT by more than 0.7 second then the clock is stopped for 1 second and this is called addition of a leap seond. The addition of 1 leap second or stopping the clock by 1 second advances UT1 by 0.3 second. ahead of TT. This creates the need for Coordinated Universal Time (UTC). UTC keeps the record of the number of leap seconds added. In this paper Delta-T is measured by integrating the deficit to the day as defined in 1900 CE (Current Era) from ancient days to 1900CE. This is compared with Delta-T as observed by Stephenson and Stephenson & Houldon (1896). The analytical values calculated by the Author match with the observed values except for the intermediate periods. This is explained by taking into account the post-glacial rebound taking place between 2000BCE and 1600CE. This match stands as a vindication of the new perspective on the birth and evolution of Solar System.