T Square

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T square

[′tē ‚skwer]
(graphic arts)
A straightedge rule with a crosspiece at one end by which parallel lines are drawn perpendicular to the edge of the drawing board.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

T square

(religion, spiritualism, and occult)

Three or more planets that together form a configuration of a “T”—two directly opposite each other and a third at right angles to each of the opposed planets—in a horoscope are referred to as a T square. To qualify as a T square, the planets directly across the chart from each other must be involved in an opposition (180° aspect) and the third planet must make a square (an aspect of 90°) to the first two. Because astrological signs at 90° angles to each other belong to the same quality (cardinal, mutable, or fixed), T squares tend to involve planets in three signs of one quality. Thus, T squares can be classified as cardinal T squares, mutable T squares, or fixed T squares (T squares that involve planets in signs of different qualities are referred to as mixed T squares).

Because all the aspects contained in a T square are hard aspects, an individual with such a configuration in her or his natal chart is presented with more challenges than the average person. At the same time, a T square is a powerfully dynamic configuration (it is considered to be the most dynamic of all configurations, particularly when the constituent planets are in cardinal signs). Once the challenges proffered by a T square have been adequately met, the individual has tremendous personal power.

In certain ways, a T square is like a grand cross (a configuration with four planets in all four corners of a chart) minus one of its “legs.” Like a table with only three legs, the T square tends to draw attention to the house where a fourth leg would be required in order to produce a stable table. Imagine, for example, a natal chart in which the three component planets of a T square are in the second, eleventh, and eighth houses. One’s attention is thus drawn to the fifth house. This indicates that if natives with this particular T square invested their energy in one or more of the matters associated with this house—children, creations, self-expression, entertainment, and so forth—their lives should become more stable. Simultaneously, this configuration indicates that the lessons learned in houses two, eleven, and eight could be brought to bear on whatever tasks were undertaken in the fifth house.


Brau, Jean-Louis, Helen Weaver, and Allan Edmands. Larousse Encyclopedia of Astrology. New York: New American Library, 1980.
Marks, Tracy. How to Handle Your T Square. Arlington, MA: Sagittarius Rising, 1979.
The Astrology Book, Second Edition © 2003 Visible Ink Press®. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

T Square


a drafting ruler with a crosspiece, or head, at one end. T squares may have a double-plane head and a ruler length of 800 to 1,400 mm or a single-plane head and a ruler length of 500 to 750 mm. When used in drafting, the head is pressed against the edge of the drawing board. A T square makes it possible to draw parallel lines with a deviation of no more than 1 mm per 1,000 mm of length. The drawing edge of single-plane T squares is set at an angle of 90° to the head. T squares with a double-plane head make it possible to draw lines inclined at any angle. T squares are usually made of hard wood.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.