Windmills, which are used in the great plains of Holland and North Germany to supply the want of falling water, afford another instance of the action of velocity. The sails are driven by air in motion - by wind. ↗
In my grammar school years back in the 1920s I used my ten-cents-a-week allowance for Saturday matinees of Douglas Fairbanks movies. All that swashbuckling and leaping about in the midst of the sails of ships! ↗
Some people may say my curved panels look like sails. Well, I am a sailor, so I guess I probably do use that metaphor in my work - though not consciously. ↗