Varahamihira: the Brihat Jataka, the Brihat Samhita and the Panchasiddhantika · Chapter 17 of 22 · Part Three · The Brihat Samhita

#Rain, wind and the earth

Brihat Samhita, chapters 21–40

Twenty chapters of the Brihat Samhita deal with weather and the signs of the earth and sky. For an agricultural people dependent on the monsoon, nothing mattered more. Varahamihira explains why at the start:

As food is the support of life and food depends upon rain, it is important to discover the laws of rain by any means (21.1).

#The "pregnancy" of clouds (21)

Following Garga, Parashara, Kashyapa, Vatsa and others (21.2), Varahamihira describes how to forecast the season's rain from the "pregnancy" (garbha) of the clouds: the clouds, winds, colours of the sky and temperatures observed in the months before the monsoon are a "conception" of rain, to be "delivered" about 195 days later, when the Moon returns to the same nakshatra. An astronomer who watches these signs "day and night", he says, will be as reliable as the sages (21.3) — and he jokes that rain prediction is so admired that a person who masters it "passes for a great astrologer" even if ignorant of everything else (21.4).

#The days of wind (22)

The four days from the eighth of the bright half of Jyeshtha (May–June) are the wind-holding days (dharana): their winds and weather, and rain as the Moon passes from Swati to Jyeshtha, foretell the rains (22.1–2). If the four days are alike, there will be prosperity (22.8).

#Measuring rain (23)

Falling rain should be collected in a vessel with a circular mouth, a cubit in diameter, and the collected rain should be measured with a vessel whose capacity is an adhaka (23.2).

This is a rain gauge, described in the sixth century: a standard opening, and a standard measure. Varahamihira goes on to forecast the season's rainfall from the rain falling as the Moon passes through particular nakshatras in Jyeshtha (23.1, 23.3), and gives — citing Vasishtha, Garga and Parashara — rules for how large an area a predicted rain will cover (23.4).

#The Moon's conjunctions (24–26)

The Moon's conjunction with Rohini (24), with Swati (25) and with the Ashadhas (26), in the months before the monsoon, and the winds and clouds at those times, forecast the year's rain and crops. These "Rohini yoga" and "Ashadhi yoga" methods were widely used by farmers' almanacs for centuries.

#Winds and immediate rain (27–28)

The winds of each direction at particular times (27), and the signs of immediate rain — the behaviour of animals and insects, the colour of the sky, the feel of the air (28).

#Crops from trees (29)

Judging from the growth of the fruits and flowers of trees and plants we may determine beforehand what articles can be had cheap and in abundance and what crops will thrive (29.1).

For example: the flowering of the sal tree indicates a good crop of white rice; the banyan, barley (29.2–3). This is a kind of phenology — reading the season from the natural calendar of plants.

#Twilights, glows, earthquakes and meteors (30–33)

• Twilights (30) and the glow of the horizon (digdaha, 31), with their omens.
• Earthquakes (32): Varahamihira tells a myth — the Earth complains to Brahma that she is shaken by flying mountains, and Brahma appoints the wind, fire, Indra and Varuna to shake her, each in a quarter of the day and night, as signs of the future (32.3–7). The earthquakes are then classed by the nakshatra of the Moon into four "circles" — of the wind, of fire, of Indra, of Varuna — each with its warning signs (dust and wind; meteors and glowing horizons...) and its effects (32.8 onward).
• Meteors (33).

#Halos, rainbows, mirages, parhelia, dust (34–38)

• Halos round the Sun and Moon (34).
• The rainbow (35), with a physical explanation: "The many-colored rays of the Sun falling upon the clouds and being broken by the winds take the shape of the rainbow in the sky" (35.1). Then its omens: a pair of perfect rainbows brings abundant rain (35.3).
• "Cloud castles" (gandharva-nagara), mirage-like shapes in the clouds (36).
• Parhelia, the "mock suns" beside the Sun (37).
• Dust storms (38).

#The horoscope of crops (40)

Chapter 40, Sasya Jataka, casts a "horoscope" for the year's crops from the planets when the Sun enters Scorpio and other signs: benefics in Scorpio or in the angles from it promise a good summer crop (40.2); Jupiter in Aquarius with the Moon in Leo, or the reverse, likewise (40.3).

#How to read these chapters

These chapters mix three things:

1. Observation and measurement: the rain gauge, the study of winds and clouds before the monsoon, the flowering of trees, the explanation of the rainbow. These can be compared with modern measurements, and such comparisons are interesting.
2. Traditional forecasting rules, such as the 195-day "pregnancy" and the Rohini yoga, which can in principle be tested against rainfall records.
3. Omens for kings and peoples, which belong to history.

#Summary

• Rain matters because food depends on it (21.1); the "pregnancy" of clouds forecasts rain about 195 days later (21); the wind-holding days of Jyeshtha (22).
• A rain gauge: a vessel a cubit across, measured by a standard volume (23.2).
• The Moon's conjunctions with Rohini, Swati and the Ashadhas forecast the rains (24–26); winds and signs of immediate rain (27–28).
• Trees foretell crops (29); twilights, glows, earthquakes (with a myth and a classification), meteors (30–33).
• Halos, the rainbow (explained by sunlight broken in clouds, 35.1), cloud castles, parhelia, dust storms (34–38); a horoscope of crops (40).

#Exercises

1. Why, according to Varahamihira, is rain prediction important?
2. Describe the rain gauge of 23.2.
3. What does the flowering of the sal tree foretell?
4. How does Varahamihira explain the rainbow?
5. Which of these chapters' methods could be tested against modern records, and how?

Answers: 1. Because food, the support of life, depends on rain (21.1). 2. A vessel with a circular mouth a cubit across collects the rain, which is measured with a standard vessel of one adhaka. 3. A good crop of white rice (29.2). 4. As the Sun's many-coloured rays falling on clouds and broken by the winds (35.1). 5. For example the 195-day "pregnancy" rule or the Rohini yoga: record the pre-monsoon signs each year, make the forecast, and compare with measured rainfall.