I always thought digging a qanat must have been miserable work, but the fact is that the human body’s peak endurance comes at a temperature that is pretty close to ground temperature.

Runners and cyclists and gardeners know that a nice 55° day you can just go forever without stopping because your body isn’t wasting any energy on perspiration. And in fact if you do stop for long you just get cold.

Temperatures in the Taklamakan can reach 50°, but that's Celsius, not Fahrenheit.

Beat me to saying the same thing, by an hour:) I've always thought qanats were a cool idea.

The also sound like the Puquios used in South America.