"Geological Transactions" volume 2 page 528.

In the "Philosophical Transactions" 1790 page 294, Dr.Priestley has described some imperfect siliceous tubes and a melted pebble of quartz, found in digging into the ground, under a tree, where a man had been killed by lightning.) The sand-hillocks of Maldonado, not being protected by vegetation, are constantly changing their position.

From this cause the tubes projected above the surface; and numerous fragments lying near, showed that they had formerly been buried to a greater depth.

Four sets entered the sand perpendicularly: by working with my hands I traced one of them two feet deep; and some fragments which evidently had belonged to the same tube, when added to the other part, measured five feet three inches.

The diameter of the whole tube was nearly equal, and therefore we must suppose that originally it extended to a much greater depth.