Beat me to it, McGrath ! (It takes me a long time to write all that "a href" stuff to make a blue clicky). BUT I did link to a slightly different page on the site :)
The site lists all the subjects and speakers right back to 1825/6. One that I remember particularly on there was the "Monkeys without Tails one on evolution that I saw when I was at school (slightly later than 1826 ..)

- jeanie