Millions of years ago a small tribe of men found that the area in which they
were living produced less and less vegetation and game each year to feed upon.
One particular year, the situation became almost unbearable and Ogu, the leader
of this small group, gathered his clan together and announced that he thought they
should move out of the area to find better hunting and foraging grounds. He knew
that the journey would be very difficult because they had to traverse a vast area of
barren land. They gathered as many supplies as they could and set off for better
lands.

After several days of traveling and being without water, the tribe became
somewhat edgy, and Ogu became very concerned. He knew that without water the
tribe could last only for a few more days, so he sent some of his most trusted and
able warriors ahead to search for water. A few days later one of the warriors
returned but did not seem too overjoyed, so the tribe thought that he failed to find
water. However, the warrior had found water but not in sufficient quantity that the
whole tribe would be sated, and he knew that the stronger ones would make sure
that they got their water even at the expense of the weaker members of the tribe.
Their animal instinct to survive far outweighed their commitment to community
survival, so the warrior knew that he must tell of his find only to Ogu.

Ogu was puzzled; he never had to face this problem in the past. He knew that
the survival of the clan depended on the survival of the weaker members, the
women and the children, as well as the stronger members. There was no easy
solution, but he knew that they had to set out in the direction of this new find.

At last, as Ogu and the tribe reached the top of a knoll, he looked down and saw
a very small oasis-so small that it supported only one palm tree. Suddenly Ogu
knew the answer. He knew he had to limit each member to a small quantity of
water. He finally got the courage to call his clan together and explain what had to
be done and why it had to be done. At the end of his speech, Ogu decreed that
each member should have only five handfuls of water so that all could survive.

Whether this story is true or mere conjecture, it could have happened and
possibly did happen in much the same way as it was told. This is the same
problem one faces in trying to write the history of flow measurement: we have
some idea concerning the history of hydraulics and fluid mechanics but little is
known about actual flow measurement. It wasn't a very popular subject then as it
isn't a very popular topic today. Flow measurement had to be accomplished to
achieve some of the successes in hydraulics in the past, but little was written about
it. The layman today thinks very little about it even though he purchases his
natural gas, domestic water, and gasoline with this technology. In the story above,
the handfuls of water could have been the first time that primitive man measured a
defined volume of liquid. Only in the years to come was the making of pottery
discovered, and wine and water were sold and traded according to liquid volume.

This little story also points out another aspect of flow measurement: it is a
common and natural thing to do. The velocity of a moving air mass or the
swiftness of a stream are topics often cited in the normal conversation of the day.
For example, this morning when I woke up the wind was howling, or was it
screeching? We would almost all agree that howling is not as bad as screeching.
Why? Experience tells us that as the wind velocity increases, the pitch of the
sound associated with it also increases. Whether or not we know the reason for
this naturally occurring phenomenon, we use the same principle to estimate wind
velocity as the modern vortex shedding flowmeter uses to measure flow in a
closed conduit. In modern times, your child, who is sitting in the back seat of the
car with his hand out the window, might say, "Dad, go faster, I can still hold my
hand out the window." Could this be the same principle used to measure flow in
target meters and pitot tubes?