and 25.2 minutes which is half a lunar day, a full lunar day is thus 24 hrs. The normal duration of the tidal cycle from low water to high water and back to low water again is 12 hrs. Life on earth, from the beginning, is the result of an incredible amount of coincidences and random "goldilocks" experiences like the above celestial collision. Our moon was formed about 4.5 billion years ago from dust and debris that coalesced after a large Mar's sized celestial body hit the proto-earth a glancing blow, tilting it 23.5 degrees, thus eventually creating our seasons. During these periods the gravitational pull of both the sun and the moon acting together cause the tides to bulge on the surface of the ocean facing them, which results in either your boat hanging off the quay wall if you have not allowed enough slack on your mooring ropes for the drop of the tide or bringing your bucket and spade with you to the beach to build sandcastles and finding no sand but only seawater on a full Spring tide. New Moons occur when the moon is aligned directly between the earth and the sun and full moons occur when the earth lies directly between the moon and the sun. "Spring Tides" occur at new moon and full moon when the tides "spring forth" and the term has nothing to do with the seasonal expression of Springtime - apart from the fact that it is also the time when animals and plants "spring forth". But this is not always the case and the ebb period between high water and low water can be "stretched", with the result that the flood tide is usually stronger than the ebb tide and also the times of the tides vary every day. The Rule of Twelfths assumes that the tides are semi-diurnal or diurnal, corresponding to the sine curve (which is not always the case at different locations on the earth, depending on the local geography and bathymetry) and also that the time between high water and low water is 6 hrs. The Rule of Twelfths can also be used to calculate approximately the duration of daylight for any given day from one solstice to another, if one knows the times of sunrise and sunset at either end. Some Tidal facts and other items of Celestial Interest
of flood - 1/12 of strength (flow or height) The Rule of Twelfths for tidal periods, in areas with tidal sine curves with regular diurnal or semi-diurnal tides, goes as follows: But this particular mention of my age and co-relation with the height of the tide has always left a deep impression on me and how closely connected our lifespan is in relation to the periods of the tides. All the Blasket Islanders at that time spoke beautiful Homeric Gaelic which was both poetic and full of metaphors as above, mostly derived from nature and the sea and the turning of the tides and the seasons. Máire was a close relative of the famous Peig Sayers, the Blasket Island story teller whose oral story-telling was written down in "Peig.
Many years ago, in Dún Chaoin, the village in West Kerry where I lived, an old woman said to me on my 33rd birthday - "Tá tu ar barr an taoide anois, a buachall! Ach cogair! Ni fada go mbeidh an taoide ag casaadh!" Which, taken at the flood, leads on to fortune Īnd we must take the current when it serves, The Tides of Life: How our lifespan is linked to the diurnal turning of the tides - the ebb and flow of life, from ebb tide to full tide to ebb tide again Shakespeare had this to say about the ebb and flow of life:
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