What is the purpose of these bricks between beams?

[scott08]

Whilst doing my loft conversion, i've uncovered a beam spanning across the hallway upstairs (I imagine it would be the same downstairs). Its 2 beams, one on top and one on the bottom, with bricks in between. I can't figure out what the purpose of these bricks would be, and why just 1 larger timber wouldn't be used? The only reason I can think is because the house steps down at the back, but the bricks aren't particularly solid so I can't see how much support is added by using them, and as far as I can tell it's just holding up a few joists either side:

 

[Wayners]

Bricks stop wood twisting or just to fill in maybe