Hour Glass Tree
An Hour Glass Tree is shaped like an hour glass and details the immediate ancestors and descendants of a particular person. That person is always found at the centre of the diagram which is also the narrowest part of the hour glass shape. If you've never seen an hour glass just think of the little timer graphic that comes up on your PC when WIndows programs need you to wait.
The diagram on page 96 of The Time Stealers is an Hour Glass Tree. An hour glass tree won't show information extending past the immediate person's family. For example on page 96 we discover that Gregory Adair had two children, Janique and Taleena but it doesn't tell us who Gregory married because Gregory's wife is not related to Sylvia Francis Strode.
Although a family tree uses the same graphic language as an Hour Glass Tree its shape is determined by the amount of information accessible about any given family. For example the family tree for my mother's side of the family, to date, includes, 570 individuals, and the diagram when unrolled is the length of my hallway. My husband's family tree is even larger. Some families from India can trace their ancestors back through many centuries far further than I can trace my ancestors.
Where as an Hour Glass Tree limits the information a Family Tree is only limited by what you can establish about who your ancestors and relatives are and how many off-spring each couple had.