Solar cycle 4 was the fourth solar cycle since 1755, when extensive recording of solar sunspot activity began.Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383–401. The solar cycle lasted 13.6 years, beginning in September 1784 and ending in April 1798 (thus overlapping the Dalton Minimum). The maximum smoothed sunspot number observed during the solar cycle was 235.3 (in February 1788), and the starting minimum was 15.9.SIDC Monthly Smoothed Sunspot Number. ""
There are some recent speculations that cycle 4, the longest solar cycle since 1755, was actually two cycles, based on the appearance of new sunspots at high solar latitudes in 1793–1796 and a reconstruction of the sunspot butterfly diagram for cycles 3 and 4,"Centuries-old sketches solve sunspot mystery", New Scientist, 1 August 2009, p. 10. although total sunspot numbers only show a single-peaked distribution.
See also List of solar cycles
References