Apply BE between (1) and (B). (It is obvious that we have chosen a streamline along (1) and (B), shown as a dotted line)
, where
and are the elevations from a reference line. (considering that the tank area is significantly larger than the tube’s size, which is always true). Mathematically, one can apply continuity in such case: .
Therefore,
Obtain . How? Apply continuity between ‘B' and ‘2’
Obtain . How? Apply BE between ‘1’and ‘2’
Substitute to obtain
, where 
and 
are the elevations from a reference line.
(considering that the tank area is significantly larger than the tube’s size, which is always true). Mathematically, one can apply continuity in such case:
.
. How? Apply continuity between ‘B' and ‘2’
. How? Apply BE between ‘1’and ‘2’
to obtain 
x
