THE JULIAN CALENDAR—‘Old Style’ (OS) —was introduced by Julius Caesar in 45 BC; ‘New Style’ (NS) was based on the Gregorian calendar introduced by Pope Gregory III in 1582. The date of the adoption of NS in preference to OS varied from country to country. In England the change followed an Act of Parliament in March 1751; this decreed that the next 1 January should be the first day of 1752, and that 2 September 1752 should be followed by 14 September to eliminate the discrepancy between the two calendars. It became common in mid-century for correspondents to give both forms of date in their letters; where this occurs in letters printed here — as in the case of Joseph Spence—the writer's practice is strictly followed.