Public lecture courses offered some scientists who were unaffiliated with official organizations a forum to transmit scientific knowledge, at times even their own ideas, and the opportunity to carve out a reputation and, in some instances, a living. The public, on the other hand, gained both knowledge and entertainment from demonstration lectures.[54] Between 1735 and 1793, there were over seventy individuals offering courses and demonstrations for public viewers in experimental physics. Class sizes ranged from one hundred to four or five hundred attendees.[55] Courses varied in duration from one to four weeks, to a few months, or even the entire academic year.