The Positive Sciences of the Ancient Hindus c4.s2.58

c4.s2.58

*Size of the Minimum Visibile; Size of an Atom.*—The supposed thickness of the just-discernible mote in the sunbeam (called a Paramánu in Technology, Silpasástra, and a Trasarenu in Natural Philosophy) follows directly from Varáhamihira’s table:—8 Paramánus make 1 Rajas (or Ratharenu,—*cf.* the Manasara), 8 Rajas make 1 Válágra (filament of hair), 8 Válágras make 1 Likshá, 8 Likshás make 1 Yúká, 8 Yúkás make 1 Yava, 8 Yavas (the Manasara has 4) make 1 Anguli (superior), 24 Angulis make 1 Hasta (cubit, lesser cubit, 18 inches). The thickness of the *minimum visibile* (the finest perceptible mote in the slanting sunbeam) is therefore taken to be 3.2⁻²⁰, or 1/349525 of an inch. The volume of a spherical Trasarenu (or Paramánu of the Silpasástra) would therefore be 4/3.π.3³.2⁻⁶³ of a cubic inch. It may be here noted that such a Trasarenu is supposed in the medical schools to contain 30 chemical atoms (Paramánus of Natural Philosophy) according to one estimate, or 60 according to another. The size of an atom must then have been conceived to be less than π.3.5⁻¹.2⁻⁶² of a cubic inch.¹ (परमाणुरजोवालाग्रलिक्षायूकं यवोऽङ्गुलं चेति अष्टगुणानि यथोत्तरम् अङ्गुलमेकं भवति संख्या.—Varáhamihira, Vrihatsamhitá, Chap. LVII., Śloka 2. जालान्तरगते भानौ यदणुतरं दर्शनं रजो याति तद्विद्वात् परमाणुं प्रथमं तद्धि प्रमाणानाम् ।—*ibid.*, Śloka 1.—*Cf.* Utpala, तत्परमाणुं नाम प्रमाणं जानीयात् । प्रमाणानां सर्वेषां तत् प्रथममाद्यं प्रमाणं परमाणुसंज्ञम् । *Cf.* also त्रसरेणुस्तु विज्ञेयः त्रिंशता परमाणुभिः)