Other Days, Other Eyes - Bob Shaw
Slow glass was an amusing scientific toy. Light traveled through it so slowly that, looking through a pane of it, you might see what had happened five minutes ago on the other side--or five years. It stopped being a toy when great new jetliners began to crash, car accidents multiplied astronomically and a mounting toll of deaths and disasters revealed its true potential. And it was no toy at all when blackmailers discovered how to use it to see into the secret life of any victim--and government officials found it could permit surveillance of any person, any time, anywhere.
Condition: Very Good. Some tanning of inside cover from age.