DAVA SOBEL, GALILEO'S DAUGHTER — Galileo arrived at [the]... relationship between distance and time without... a reliable unit of measure or an accurate clock. Italy possessed no national standards..., gauging... by flea's eyes, hairbreadths,... hand spans,... and the like.
| A. | Full, rich outpouring of melodious sound; tuning fork | DIAPASON |
| B. | Heed an alarm; come to life | AWAKEN |
| C. | Ready to erupt at any moment | VOLATILE |
| D. | Profoundly bad | ABYSMAL |
| E. | Body with rings that were first seen in 1610 | SATURN |
| F. | Angle-determining instrument used in celestial navigation | OCTANT |
| G. | Engage in a b-boying battle (hyph.) | BREAKDANCE |
| H. | Ground zero for a temblor | EPICENTER |
| I. | Realm of Croesus, now part of Turkey | LYDIA |
| J. | Worker also known as an aurifex | GOLDSMITH |
| K. | Come before, be older than | ANTEDATE |
| L. | Balance in the sky | LIBRA |
| M. | Rashly, without due consideration (2 wds.) | INHASTE |
| N. | Complying with the rules | LAWFUL |
| O. | Act of climbing the walls as a siege tactic | ESCALADE |
| P. | Kowtowing or bowing | OBEISANT |
| Q. | Horn signaling the end of Yom Kippur | SHOFAR |
| R. | Long coat worn in westerns | DUSTER |
| S. | Cooper, potter or weaver, e.g. | ARTISAN |
| T. | Surplus; idle; pristine | UNUSED |
| U. | Band with the 1986 hit "Land of Confusion" | GENESIS |
| V. | Acme, climax, zenith, peak (2 wds.) | HIGHPOINT |
| W. | Idea-based; speculative | THEORETIC |
| X. | Give a stamp of approval | ENDORSE |
| Y. | Physics Nobelist of 1904 who explained why the sky is blue | RAYLEIGH |