When did Auguste Comte begin presenting lectures on positive philosophy?

Auguste Comte first began presenting his lectures on his "system of positive philosophy" to a private audience in 1826.1

Following a serious nervous breakdown, he resumed his projected lecture series in 1828/29, which was successfully concluded and subsequently redelivered at the Royal Athenaeum during 1829–30. These lectures formed the basis for his major work, the Cours de philosophie positive (1830–42).12