641.00 High Tide and Low Tide

641.01 No tension member is innocent of compression, and no compression member is innocent of tension. That is, when we are tensing a rope visibly and axially, its girth contracts as it goes untwistingly into compression, precessionally, compressing in planes at 90 degrees to the axis of our purposeful tensing. We learn experimentally that tension and compression always and only coexist and operate precessionally at right angles to one another, covarying in such a way that one is ebbing toward low tide while the other is flowing toward high tide, or vice versa, in respect to relative human apprehendability, as they fluctuate between visibly obvious and human subvisibility.

641.02 Tension and compression are inseparable and coordinate functions of structural systems, but one may be at its “high tide” aspect, i.e., most prominent phase, while the other is at low tide, or least prominent aspect. The visibly tensioned rope is compressively contracted in almost invisible increments of its girth dimensions everywhere along its length: This low-tide aspect of compression occurs in planes perpendicular to its tensed axis. Columns visibly loaded by weights applied only to their top ends are easily seen to have their vertical axes in compression, but invisibly the horizontal girths of these columns are also in tension as the result of a cigar-shaped, swelling pattern of forces acting in the column at right angles to its loaded axis, which tends, invisibly, to transform toward the shape of a squash or a banana. As a result of the visible, or high-tide, vertical compressioning aspect of such axial loading of the column’s system, this swelling force imperceptibly stretches, or tenses, the column’s girth as a low-tide reciprocal function of the overall structural-integrity reciprocity.