With regard to burnt brick... If not made of good clay or if not baked sufficiently, it shows itself defective... when exposed to frosts and rime. Br… - Vitruvius

Then again, in the human body the central point is naturally the navel. For if a man be placed flat on his back, with his hands and feet extended, and a pair of compasses centered at his navel, the fingers and toes of his two hands and feet will touch the circumference of a circle described therefrom.

Leave a cavity behind the [wall] facings, and on the inside build walls two feet thick, made of red dimension stone or burnt brick or lava in courses, and then bind them to the fronts by means of iron clamps and lead. ...the beds and builds, all settling equally and bonded at the joints, will not let the work bulge out, nor allow the fall of the face walls which have been tightly fastened together.

If then, at this great distance, our human vision can discern that sight, why, pray, are we to think that the divine splendor of the stars can be cast into darkness?