ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

CHAPTER XIII Brahmagupta and Astronomical Instruments The Twenty-second Chapter of the Brāhmasphuṭasiddhānta is known as the Yantrādhyāya or a chapter on instruments. There is a description of seventeen types of time-reckoning instru- ments (Kāla-yantra)¹ :

1. Dhanuryantra—Bow instrument.
2. Turyagolaka yantra—Quadrant (one-fourth sphere)
3. Cakra yantra=wheel or circle.
4. Yaṣṭi yantra—a pole or staff instrument.
5. Śaṅku yantra—Gnomon.
6. Ghaṭikā yantra—a clock or pot instrument.
7. Kapāla yantra—Bowl or potsherd instrument.
8. Karttarī yantra—Scissor or knife ; cutter.
9. Pīṭha yantra=Pedastal or seat instrument.
10. Salila yantra—Water-leveller.
11. Brahma or Śāṇa yantra—For describing circles.
12. Avalamba Sūtra—Threads with plumbs (Plumb lines).
13. Karṇa or chāyā-karṇa—A set of squares for diagonals.
14. Chāyā or śaṅku-chāyā—Sundial. ──────────────────────────────────────────────────
15. सप्तदश कालयन्त्राण्यतो धनुस्तुर्यगोलकं चक्रम् । यष्टिः शंकुर्घटिका कपालकं कर्त्तरी पीठम् ॥ सलिलं भ्रमीऽवलम्बः कर्णश्छाया दिनार्थमर्कोच्चः । नतकालज्ञानार्थं तेषां संसाधनान्यष्टौ ॥ —BrSpSi. XXIII, 5-6