Complex sentence: Croquet became highly popular as a social pastime in England during the 1860s; by 1867, Jaques had printed 65,000 copies of his "Laws and Regulations" of the game.
Split into simpler sentences: Croquet became highly popular as a social pastime in England during the 1860s. By 1867, Jaques had printed 65,000 copies of his "Laws and Regulations" of the game.