In the Vedic sacrificial ritual, when a sacrifice is performed for the benefit of a sacrificer, the dimension of the sacrificial altar is derived from the dimension of the sacrificer. The ritual requires that the altar be constructed of layers of bricks, from which the deity is invoked through the power of hymns. Having been invoked, the deity flies to the site of the sacrifice in his ratha, or “chariot,” partakes of the sacrifice offered from the altar, and then departs. After this ritual, the altar is abandoned. Accordingly, texts describe altars as falcon-shaped and, to one extent or another, these altars conform to the shape of a bird, or more accurately, the shadow of a bird on the ground.

There are a number of possible representations of falcons, most of which are composed of shapes which bear no resemblance to temple plans, and thus do not share a common constructive diagram. One of the few representations of this falcon that resembles a temple plan is given in the Manava Shulbasutra, which is part of a class of texts called shulbasutras, or “cord-rules,” which treat of altar construction. The altar is called Caturasra Shyena, or “four-sided falcon,” and consists of a ‘falcon’ with a square body and head, two rectangular wings, and a rectangular tail.

The first step in the construction of the altar is to determine the size of the angula, or “finger,” the fundamental unit of measure used to determine the various dimensions of the altar. The Manava Shulbasutra gives two options for determining the size of the angula, the first based on division, and the second based on multiplication.

According to the first method, if the sacrificer is standing with his feet flat on the ground and his arms raised, then this height is said to be 120 angulas; and if the sacrificer is standing on his toes, then this height is said to be 125 angulas. The length of 120 angulas is called a purusha, or “man.” In the second method, the distance between the lines forming the middle part of the middle finger of the sacrificer is equal to one angula, or, if the sacrificer is short, then one angula may be formed from the width of six barley grains. Thus, unless the sacrificer’s body is found to be deficient, the dimension of the sacrificial altar derives from the dimension of the sacrificer.

The second step in the construction of the altar is to determine its location and orientation. The orientation is both spatial and temporal; the orienting procedure determines not only the direction of the ritual object, but also the time of its construction. Similar procedures were utilized to orient any propitious event.

The simplest procedures for determining time and orientation in the Indian tradition utilize gnomons and ropes. The earliest example of the application of this technique occurs in the orientation of the Vedic sacrificial altar. The shadow of a gnomon is used to determine the primary, east-west line, and pegs, cords, and rods are used to layout a square of 240 x 240 angulas, represented by the gray area in the following figure:

In the figure above east is located at the top, following the Indian tradition of the representation of orientation, and thus the primary east-west line is vertical. When the size and orientation have been fixed, the altar is constructed out of five layers of bricks, each layer consisting of 200 bricks. The height of each layer is six angulas, so that the total height is 30 angulas, which is equal to the width of the largest brick. The ‘body’ of the falcon is square, the same square with a dimension of 240 angula, or 2 purushas, that was formed at the time of location and orientation of the altar.

In order that the four limbs of the falcon do not break away from the body, structural integrity is maintained by overlapping layers with different arrangements of bricks. The bricks of the first, third, and fifth layers of the Caturasra Shyena altar are are constructed with three different bricks in the following quantities and sizes, where a = angula:

110 30a x 30a

85 12a x 12a

5 12a x 6a

The second, and fourth layers of the Caturasra Shyena altar are constructed with four different bricks in the following quantities and sizes:

110 30a x 30a

75 12a x 12a

10 12a x 6a

5 18a x 12a

The square ‘body’ of the altar may thus also be described as an 8 x 8 grid, a pattern which is most apparent in the arrangement of bricks in layers 1, 3, and 5. This 8 x 8 grid is proportionally equivalent to the plans of Indian temples, and the areas enclosed by the representations of walls in tantric yantras and mandalas.