Skywriting

There is a company in New York that skywrites 50 marriage proposals a year.   And how exactly does skywriting work?   First you have to mix paraffin oil into your exhaust so you leave a nice big contrail.   Then you check to make sure you have a strong stomach because chances are that sometime during the skywriting process you will be upside down.  You and your friends that is.   A single plane can write about 6 letters.   So you write Verla, the others can manage "Marry Me".   A single letter can be one mile high.   That's good in case Verla works in a skyscraper.   You can see them from 30 miles away - good if Verla lives in the suburbs.  Skywriting has been around since 1922 and was immediately co-opted for advertising.   Surprise!

By the way, 'Surrender Dorothy' was written in a tank of water and oil. Well, I didn't believe that broom could fly anyway.

Source:  Library of Congress Everyday Mysteries
Books About the History of Airplanes