February 11 - Pennsylvania Hospital, the first in Colonial America, is opened.
June 6 - Third fire in Moscow in 2 weeks; 1/3 of the city is destroyed.
September 2 - The last day of Julian calendar in Britain and its colonies. The next day is September 14, according to the Gregorian calendar. During the Middle Ages, astronomers and mathematicians observed that the calendar year was not completely accurate with matching solar years. Errors in the Julian calendar were noted by church officials and scholars because church holidays did not occur in their appropriate seasons. In 1582, Pope Gregory XIII (1502–85), who was pope from 1572 to 1585, and his astronomer and mathematician created a new, reformed calendar known as the Gregorian or New Style (N.S.) calendar. It was adopted first in Roman Catholic countries. Protestant countries adopted the calendar during the eighteenth century. In order to make the calendar adjustment, eleven days were dropped from the month of September 1752. An eleven-day adjustment in 1752 was needed because one more day had been lost since the calendar was changed in 1582. The year 1751 began on 25 March and ended on 31 December 1751. The first day of the year was now January 1st and the last day was December 31st—the calendar we use today. Thus, 2 September 1752 was followed by 14 September 1752.
