n In the 1940s, Austrian-born actress Hedy Lamarr co-invented a communications system intended to make radio-guided torpedoes harder for enemies to detect. The invention was the basis of the “spread-spectrum” technology used today in cordless telephones and WiFi connections. (Thanks to Art Leone of Seattle.)

No peeking: The interior pages of American passports feature background illustrations of U.S.:

A) Birds

B) Presidents

C) State seals

D) Postage stamps

Friday’s answer: According to the Arthur Conan Doyle story “His Last Bow,” Sherlock Holmes wrote the “Practical Handbook of Bee Culture” in his retirement.