+...+...+...+...+...+...+...+...+
: ::::: ::::: ::::: :::::
+...+...+...+...+...+...+...+...+
::::: ::::: ::::: ::::: :
+...+...+...+...+...+...+...+...+
: ::::: ::::: ::::: :::::
+...+...+...+...+...+...+...+...+
::B:: B ::B:: B ::B:: B ::B:: B :
+...+...+...+...+...+...+...+...+
: ::::: ::::: ::::: :::::
+...+...+...+...+...+...+...+...+
::::: ::::: ::::: ::::: :
+...+...+...+...+...+...+...+...+
::::: ::::: ::::: ::::: :
+...+...+...+...+...+...+...+...+
: ::::: ::::: ::::: :::::
+...+...+...+...+...+...+...+...+
This cannot be done with fewer bishops than eight, and the simplest
solution is to place the bishops in line along the fourth or fifth row
of the board (see diagram). But it will be noticed that no bishop is
here guarded by another, so we consider that point in the next puzzle.