"Spacing practices for the first couple centuries of the printing press were quite variable. But they began to coalesce into certain sets of standards in the 1600s, which became accepted conventions in the 1700s. More than a century before our Chicago Manual editor’s 1870 cut-off date, printers in England and America had relegated the idea of a large space after the period to the standard introductory rules taught to the beginning typesetter. ¶ As an aside, here’s my own theory about the Chicago Manual editor’s made-up date of 1870: that’s right about the time that the first commercially available typewriter started to be sold. However, since the practice was standard for over a century before this date, the whole “big spaces after periods come from typewriters” claim is clearly a myth." - × × ×