Any hints, tips or otherwise about splitting bricks *lengthwise"? To make
in effect a thinner brick?

I've had mixed results cutting bricks across their width, and for that I had
a bolster chisel slighter wider than the bricks. Do I have any chance at
all of success in the other direction?

I know that brick slips are available but I only need a few and there would
be some satisfaction in, er, doing it myself.

Thanks.