Problems with calculating points in a Mercatorian Map

hi i’ve implemented a little component, which connects to OSM and connecting the received tiles. now ive got a wonderfull map, and the right bounding box calculated but i recognized that in mercatorian maps there are different spaces between latitudes. Do anybody knows how i can calulate right points by given long/lat and the bounding box?

There is some information about what you need to do at DonÂ’t forget the database isnÂ’t tied to any projection and you can use whatever suits your needs.

What do you mean? ive seen the wikipedia article, but ive got no idea how i can implement it, so that i just take the bounding box and then distribute the different latitudes over it…