Yantras or Mechanical Contrivances in Ancient India c2.167

c2.167

The merits of a good machine, *yantra-guṇas*, are as follows:—
1. Proper, proportionate utilization of the elements constituting it.
2. Well-knit construction.
3. Fineness of appearance.
4. Inscrutability.
5. Functional efficiency.
6. Lightness.
7. Freedom from noise where it is not part of the scheme.
8. A loud noise when noise is intended as an end.
9. Freedom from looseness.
10. Freedom from stiffness.
11. Smooth and unhampered motion.
12. Production of the intended effects (in cases where the ware is of the category of curios).