There is also this video. This is what I would like to try. Also, it has some cool music!
https://youtu.be/OZtWewsZAsIWithout any experience, this looks like a good way to fire glandes because of how slow the temperature of the glandes will heat up. I think natural clay as thick as a gland would be prone to cracking and even explosions as Jaegoor warned. It will not get as hot as other methods but it will sinter and I think it will take less time babysitting than other ways.
Also, I don't have an oven so prebaking clay means putting it out near a fire as Cherokee potter explained in his full comment. But even with a pre-bake, the clay still needs to fire slowly because it will shrink. Fire to quickly and cracks will form (and probably residual tensile stresses that make the pottery weak).
Then again, Morphy's actual experience says otherwise.
Anyway, thanks for all the responses!