# Burning Time

You have two one-hour fuses: If you light one, it will be consumed in exactly one hour.

Unfortunately, they’re badly made — some sections of each fuse burn faster than others. You know only that each full fuse will burn in one hour.

Using only these two fuses (and matches to light them), how can you tell when 45 minutes have passed?

# Shafted

From Henry Dudeney:

A ball 13 inches in diameter has a 5-inch hole drilled through the center. How deep is the hole?

# A Riddle

At a Cambridge dinner, Arthur C. Clarke asked Clive Sinclair, “What was the first human artifact to break the sound barrier?”

What was it?

# Fugue State

John lives in an East Coast state and Mary in a West Coast state. During a phone conversation one night, they realize that it is the same time in both locations. How can this be?

# A Vanishing

Patented in 1896, Sam Loyd’s “Get Off the Earth” puzzle reportedly sold more than 10 million copies during the puzzlemaker’s lifetime, making it one of the most popular puzzles of all time.

There are 13 men in the figure on the left. Rotating the earth produces the figure on the right — which has 12 men. What happened to the 13th man?

# The Assassin

By Sam Loyd. Black to mate in four moves.

# A Day Trip

A man drives 1 mile to the top of a hill at 15 mph. How fast must he drive 1 mile down the other side to average 30 mph for the 2-mile trip?

# Stairway to Seven

You hate visiting your girlfriend because there’s no elevator in her apartment building. And now she’s moved from the fourth floor to the seventh. How many times longer does this make your ascent?

# His and Hers

Many masculine nouns can be converted to feminine with a suffix, as HERO-HEROINE and HOST-HOSTESS.

Name a feminine noun that can be converted to masculine with a suffix.

# Open and Shut

Every room in my house has an even number of doors.

Prove that the house has an even number of exterior doors.