how do you sacrifice population?

[Fart]

I have the civic slavery but I can't figure out how to use it.

 

[Sisiutil]

Have a look in the city screen at the bottom right. Just to the left of the mini-map you'll see a rectangular set of buttons/icons with the word "DRAFT" at the top. Immediately below it are two buttons for hurrying production. The one on the right uses gold to hurry production (under the Universal Suffrage civic). The one on the left sacrifices population--that's the one you're after.

 

[GenMarshall]

Also, its important to have enough population points in order to use it since 1 Pop = (I forgot the exact amount) Hammers.

 

[salty mud]

Beware - Your cities can become very unhappy using this to much!

 

[ratrangerm]

Also, if you plan to build a settler, make sure you don't whip when your population is 2. Building a settler in a city with population of 1 takes way too long. It takes a while in 2, but isn't too bad, although I usually prefer to build settlers in city size 3.

 

[Sisiutil]

The most thorough guide around to using slavery can be found HERE. (Scroll down to the section titled, "Whip 'til your hands bleed".)