A more symmetrical disposition of them could, however, be adopted by placing them zigzag, or in such a way as to form two helices, one of which would move in a particular direction, and the other in a different way.

Unhappily the schooner did not possess a helix, by which the action could be increased to sail faster.

Even this small spot produced a fine white, brown-banded Helix, not found elsewhereit occurred on the branches of the cotton-trees.

The spring would represent the helix, and the surface of the water the moving plane.