In 1909, Scott Perky of Niagara Falls patented a font where each letter and symbol has a vertical line of symmetry. This allows you to write a word either forwards or backwards without needing to change or reverse the characters.
In his patent filing — which is online here and is quite delightful to read — Perky notes that his font would allow you to print a document with each line going in the opposite direction. Or to put it another way, you'd read the first line from left to right, the next line from right to left, and then over and over again, zigzagging down the page.
As Perky argues, this would reduce the amount of eye-transit in reading, because you wouldn't be continually zipping your eye across the page, going from the end of one line to the beginning of the next:
The invention consists in certain means of printing alternate lines, whereby the reading can be done from left to right and from right to left in a continuous manner, and the skip ping from the end of one line to the opposite end of the next is avoided.
It is hardly necessary to allude to the strain upon the eyes and brain, which results from much reading. To students, researchers and others whose lives are cast among books, any device which promises to facilitate reading in such wise as to lessen fatigue of the optical tract, and consequent headache and brain fag, will appear of unusual impor In ordinary reading where the intelligent action of the brain is exerted through the eyesin movements from left to right with alternate senseless skippings from right to left, there are some disadvantages which have to do, not only with the irrelative exercise of the brain in finding the beginning of the new line while remembering the connection of the text, but also with the rapidly recurring re versions of the eye balls in skipping back ward, which may be compared in effect to the rapid flashes of alternate light and dark through a paling fence as one passes by at high speed.
This style of writing is actually quite old — it was a common way of inscribing stone in ancient Greece, known as "Boustrophedon" writing, as I learned from Randy Ludacer's excellent post on Perky's font.
Perky is right about the eyestrain that comes from eye-transit, but … wow, I'm not sure having to decode words in both directions would be less tiring on the ol' noodle.
Nonetheless, as with all inventions that are truly bonkers, my hat is off.
If you want to see what text looks like printed in this zig-zagging format, Ludacer took the opening lines of Perky's patent filing and set them in Perky's own font! Le voila:
(Via Weird Universe)