the surviving, brother is excluded, because only 
of the half blood--the father cannot be heir,
because an inheritance cannot lineally ascend,--
but the uncle is heir.  Suppose the uncle then to
be seised of the land, and to die without issue,--
if the father be alive, tho' he could not claim
by lineal ascent from the son, yet he may claim
as heir of the uncle of the first purchaser--If
the father should die before the uncle, the brother
of the half blood of the first purchaser may
claim, as heir of the uncle, the person last
seised, or if the father should survive the uncle, 
and die seised, the brother of the half blood of 
the first purchaser, may claim as heir to his father,
the person last seised.  This is called a
rule of evidence in case of descent, and the legal
presumption is, that the person who is heir
to him who was last seised is also the heir of
the first purchaser; and yet it appears from the
cases put, that the consequence doth not agree
in fact, with the legal supposition, on the application
of the above rule of evidence.