Pramāṇa · Search · About · API

The Positive Sciences of the Ancient Hindus c5.s4: Section 4. Motion of Fluids

The Positive Sciences of the Ancient Hindus c5.s4

Language
English

Section 4. Motion of Fluids

c5.s4.2

Current motion (स्यन्दन, downward flow in a stream), upward motion (आरोहण, *e.g.* evaporation, boiling, etc.), and capillary motion (अभिसर्पण, as in plants and porous vessels) are three varieties of fluid motion which require explanation. To this may be added vortical motion (संमूर्च्छन), and स्यन्दन, wave motion, which will be noticed in the chapter on Acoustics.

c5.s4.3

1. Current Motion (स्यन्दन).

c5.s4.4

This is conditioned by fluidity in particles, but Śankara Miśra notes that in the downward flow of water, gravity in the fluid-particles is the efficient cause (गुरुत्वात् निमित्तकारणात् असमवायिकारणेषु—Śankara Miśra, उपस्कार). When the water is enclosed on all sides, as in a vessel, the downward flow (स्यन्दन) is counteracted. Here the fluidity does not produce motion, because, in the case of the particles in contact with the enclosing body, there is the resistance (प्रतिबन्ध) of the latter, which is transmitted to the other particles, and this counteracts the fluidity. (स्रोतोभूतानामपां स्थलाग्निसामिसर्पर्पं यत् तत् द्रवत्वात् स्यन्दनं कथं समन्तात् रोधः संयोगेन अवयविद्रवत्वम् प्रतिवद्धं उत्तरोत्तराश्वयवद्रवत्वानि संयुक्तसंयोगैः प्रतिबद्दानि — Praśastapâda, कम्मैग्रन्थ ।)

c5.s4.5

2. Upward Motion (आरोहण, *e.g.* evaporation).

c5.s4.6

In evaporation the fluid-particles are rarefied, and remain in a fine state of suspension; the rarefaction is due to the impulse (नोदन) or impact (अभिघात) of the heat-particles in the sun's rays, and the upward movement is due to their contact with the air under this impulse or impact. Śankara Miśra notes that in boiling there is a similar upward movement of water-particles under the impact of heat-rays. (नाड्यो वायसंयोगात् आरोहणं नोदनापीडनात् संयुक्तसंयोगात् च । Sûtras 5 and 6, Âhnika 2, Chap. 5, Vaiśeṣika Aphorism. यथा स्थालीस्था आपः क्कथ्यमानाः वायुनुन्नवह्नि-रश्मय ऊर्ध्वं नयन्ति—Śankara Miśra, उपस्कार ।)

c5.s4.7

*N.B.*—These two Sûtras of Kanâda have been interpreted by the late Gangâdhara Kaviratna in his commentary to refer to the upward conduction of water in pipes by the pressure of air.

c5.s4.8

The mention of the transmitted pressure (संयुक्तसंयोग) of the air seems to lend some countenance to Gangâdhara's view, and the word Nâḍi (नाड्यः) offers no difficulty, being taken in its usual sense, "pipe" (नालिका, Nalikâ), while the current interpretation does violence to the common acceptation of the word.

c5.s4.9

3. Capillary Motion (अभिसर्पण).

c5.s4.10

Two instances are given—the ascent of the sap in plants from the root to the stem (अभितः सर्पणं मूले निषिक्ता- नाम्पां वृक्षे—Śankara Miśra), and the penetrative diffusion of liquids in porous vessels, *e.g.* of the oil or ghee in an earthen jar (कुम्भादौ अन्तर्निहितानां तैलघृतादीनां स्यन्दनं अपनश्च). Heat-particles have a like penetrative power (दृष्टश्चानिरोधो भर्ज्जन कपालादौ तेजसः पच्यमानद्रव्यपाकसिद्धेः कलशे च निक्षिप्तानां अपां शीतस्पर्शग्रहणादनिरोधः—Jayanta, न्यायमञ्जरी, Âhnika 8, इन्द्रियाणां प्राप्यकारित्वम्).

c5.s4.11

This is ascribed to *adṛiṣṭa*, as the cause cannot be ascertained by either perception or inference (including hypothesis) (प्रत्यक्षानुमानाभ्यां अनुपलभ्यमानकारणम्—Śrîdhara).

Linked texts (3)