One theory says that this endearing cat sound is caused by the vibration of the false vocal cords
A purr
Developed by Edward Jenner, the first true vaccine was designed to protect against this disease
Smallpox
Built in 312 B.C. to link Rome & the South of Italy, it's still in use today
The Appian Way
Another name for a search (like for a grail?)
Quest
It's the hall where the Declaration of Independence was signed
Independence Hall
Eating almost 3,000 kilos of meat a year, this cat is the largest land mammal with an all-meat diet
Tiger
When combined with oxygen, this lightest chemical element makes water
Hydrogen
For the last 8 years of his life, Galileo was under house arrest for espousing this man's theory
Copernicus
A medical charlatan
Quack
It's the third-largest city in Kansas
Kansas City
This swift feline of Africa is the only cat that cannot retract its claws
Cheetah
Measured in ohms, it's the R in Ohm's law, V=IR
Resistance
About 3000 B.C. the Sumerians invented this writing system which used triangular marks
Cuneiform
This archaic word for "said" is associated forevermore with a raven
Quoth
Number of letters on your standard 8-sided stop sign
Four
Special muscles control these, also known as vibrissae, to help kitty feel its way around in low light
Whiskers
About 65% of iron in humans is in the form of this, which transports molecular oxygen from the lungs through the body
Hemoglobin
7 years after crossing the Alps, he reached the gates of Rome with his troops in 211 B.C., but didn't get in
Hannibal
This wet, boggy ground can put you in quite a predicament
Quagmire
In the binary number system, this number would be 01
1
Of the 2 types of cells that change light into nerve impulses, cats are loaded with these, for better night vision
Rods
This green plant pigment is also found in algae & in some bacteria
Chlorophyll
After finding this man, Henry Morton Stanley spent the next 4 months traveling with him
Dr. David Livingstone
Because it's liquid & flows rapidly, Mercury is also known by this name
Quicksilver
It's the collective 2-word name for the extinct bears who lived in caves 1,000,000 years ago
Cave bears