Geoscience Reference
In-Depth Information
the first part of the question first, Dixon contributed very little,
certainly nothing in print, to the debate on the age of the Earth, but
Joly contributed a great deal. He was to determine the age of the Earth
by various methods, and his ideas on the subject were of considerable
influence for nearly thirty years until his death in 1933.
Their expeditions to collect coccoliths in 1897 were instrumental
in Joly's devising his earliest method of determining the age of the
Earth, in which he examined the sodium content of the oceans. It is
probable that as Dixon and Joly examined their catch, and then relaxed
on deck, the conversation would have turned to other scientific
problems. After all, it was these two men who cracked the sticky
botanical question of how sap gets to the top of even the tallest trees.
They showed in 1895 that the transpiration (or water loss) from leaves
in plants sets up a pressure gradient in leaf and plant conductive cells
that pulls the sap upwards. They were very close, shared holidays to
the Alps, and certainly many of their ideas published separately would
have been discussed and dissected.
Who was Joly? He was a man who plays an often central role in
this story, and in many others, but whose contributions are now
largely forgotten both in Ireland as well as in scientific circles, except
to a few historians of science.
He was born on 1 November 1857 in Hollywood House (the
Rectory), Bracknagh, County Offaly, the third and youngest son of
the Reverend John Plunket Joly (1826-1858) and Julia Anna Maria
Georgina ne´e Comtesse de Lusi. The Joly family originated in France,
but came to Ireland from Belgium in the 1760s. Joly's great-grand-
father served as butler to the Duke of Leinster who gave the living of
Clonsast parish to the family. After the untimely death of his father
the Jolys moved to Dublin where John received his education at the
celebrated Rathmines School run by the Reverend Charles William
Benson. Benson, who was a keen ornithologist and author of a note-
worthy slim volume Our Irish Song-birds, offered a liberal education,
and encouraged individuality. Joly displayed a keen interest in and
curiosity about science and continually tinkered with equipment,
