is the practice of writing longhand
on a sheet of paper, then turning it over and writing page two - and then going back to page one, rotating
the paper 90 degrees
, and writing over it again to save paper.
There are several methods of cross writing. The writer can write directly on top of the original words; write in the margins; or write a second page between the lines of the first. The latter two methods are more legible, but offer less extra space.
While cross writing saved on the often high cost of paper, that was not its only purpose. In the early days of postal delivery, from sixteenth century England to the Pony Express, postage was often charged per page. This further raised the cost of a letter. Cross writing added some privacy to personal correspondence, because it took extra effort to read between (or through) the lines.
Sophronia Crosby's letters, which are scanned in at http://clio.fivecolleges.edu/mhc/banister/a/2, are an excellent example of cross written margins. The Papers of Philander Chase project, at http://www2.kenyon.edu/khistory/chase/exhibit/earlyknoxcounty/slide24.htm, has beautiful pictures of cross writing done fully.
Sometimes letters were even "re-crossed," which meant writing the third and fourth pages in crossed style and then going back to page one/three, turning it forty-five degrees, and cross writing over it again. This way six pages of writing could fit onto one sheet of writing paper. History 4U describes the problems that this causes researchers when six layers of ink have bled through a piece of paper already several centuries old, and even includes a picture of a document with three layers of cross writing at http://www.history4u.info/page18.html.
Although cross writing was a very common practice before the age of typing, it was not always a popular one. In Eight or Nine Wise Words About Letter Writing,
Charles Dodgson wrote, "When you get to the end of a notesheet, and find you have more to say, take another piece of paper--a whole sheet, or a scrap, as the case may demand: but whatever you do, don’t cross! Remember the old proverb 'Cross-writing makes cross reading'. 'The old proverb?' you say, inquiringly. 'How old?' Well, not so very ancient, I must confess. In fact, I’m afraid I invented it while writing this paragraph!"