John M answered Zeke K's question of why the zero is on the top and ten
is on the bottom.
I was thinking about this since the original question was asked, and I
think it is difficult to predict how most people will purchase gas.
Some people will want to fill their tank, and they don't know in advance
how much gas it will take. These people want the zero on top. They
fill their tank until it is full, and the scale tells them how much they
used.
Other people will want a specific amount of gas. These people would
prefer the zero on the bottom so they can fill the glass container to
the amount they plan to purchase.
It seems it might be good to have both scales present, but I cannot
remember if I ever have seen any antique pumps with both scales.
For myself, my gas buying habits changed with my income. Back when I
was a teenager buying 25-cent/gallon gas, I might have had only a dollar
in my pocket, so I knew I only wanted 4 gallons even though my tank
might have had room for considerably more than that.
As my income grew, I never partially filled my tank... I always topped
it off.
The really interesting question is whether the current trend in the
price of gas will force me back into my teenager pattern of buying only
as much gas as I could afford!
Of course, with the modern gas pumps it is easy to do it either way.
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu