Change size of time slots

I want to change the size of the time slots on week view so that more fit into the page. At the moment I can't see any way of doing this. If I adjust the size of the whole iCal window, it just makes the time slots bigger and smaller, the same amount fit on the page.

This means that I have to scroll up and down to see whats happening in the morning and the evening which is very annoying.