In my experience, it makes no difference which way you plant them. One thing you can try:
Put the seeds between layers of moist paper towels in a warm spot indoors, and check them daily. As soon as you see the little roots pop out--probably near the pointy end--plant them on edge, root down, at the proper depth. Careful that the root doesn't break!
That will not only satisfy your curiosity, but will bypass any problems with the soil being too cold to support the early stages of germination.

Thanks Tug but did you mean plant them on end -point downwards - the direction the roots are going ? Will definitely give it a try.

I always lay mine horizontal but on their edge [like carrying a surfboard]. compass point makes no difference if our experiments are anything to go by. My girls planted seeds in all cardinal points and ones inbetween, egged on by their dad and it made no difference. we found waiting until April was more successful than sowing in march, even tough both sets were in a propagator at the same temperature.

I agree, makes no difference which way you plant the seeds. Just plant them, they will figure out which way to grow. I think the paper towel method slows them down more than anything and you risk damaging them, they don't like being disturbed. The main thing is rich humus soil that NEVER dries out, full sun and enough space to sprawl or climb. Plant more than you think you'll need because various plagues will claim a couple plants.