I've got the gel, the flashlight, the priest's clothes, the tweezers, the notebook, I've copied down the symbols off the tomb, I've got the two photos, the brick and the magnifying glass. I've looked at the clock puzzle in Gabriel's Grandma's attic... I've exhausted all conversation options, as far as I can tell. And now everything seems to have stopped.

Am I meant to be able to figure out the clock puzzle with what I know and have so far? If so, god damn it, I don't expect to get too far in this game. If not, can anyone give me a clue what to do next - not a specific instruction, just the location it occurs in or something like that. Thanks.

Thanks, though I'd actually figured out the mine thing a short while ago, but since your hint was indeed correct - and also the level of hint I was originally looking for - I'll tag your post as the solution. But god damn it, everything in that park seemed so throwaway, mainly since Gabriel had nothing to say to any of them, so I was kind of ignoring it.

You're welcome. Yeah that's actually one of the tougher/less logical puzzles in the game IMO. Strange it's on the first day.
Someone in this thread http://www.gog.com/en/forum/gabriel_knight_series/thinking_of_buying_the_collection recommends using the UHS for just such occasions. Which I can't recommend or not but it looks like it might be the solution to your problem should you hit a similar wall in the future.

Thanks for the link, I may have to use it pretty soon since I seem to have hit another Jackson Square dead-end...