Wodan, this technique using the carry over hammers from Slavery is a very powerful way to build wonders. Much faster than working inefficient tiles like plains hills.
The sequence I use in Warlords is something like this. Assume a high food city with say 10 base hammers from tiles and a food surplus of say +14 from floodplains, grassland farms and good food tiles. Assume the wonder has been building for a few turns and gets a bonus from stone
turn n: building wonder, 10 hammers + 25% OR + 25% forge + 100% stone = 25 hammers applied to wonder
turn n+1: build horsearcher, 10 hammers + 25% forge = 12 hammers (38 remaining)
turn n+2: (whip 2 pop to complete horsearcher = 60 hammers, + 10 hammers) = 70 base hammers. Note only 31 base hammers +25% forge completes horsearcher and 39 hammers overflow.
turn n+3 build wonder, Overflow 39 hammers, +10 hammers = 49 hammers , + 25% OR + 25% forge + 100% stone = 122 hammers applied to wonder.
The net effect of the three turn sequence n+1, n+2 and n+3 is to produce a useful unit = horsearcher and apply 47 more hammers to the wonder than normal at the cost of 2 pop. With a food surplus of +14 over 3 or 4 turns we can expect to regrow the 2 pop. Under HR the horsearcher offsets the unhappiness. This sequence can be applied 3 or 4 times to speed up wonder production. In 3 turns we are getting the equivalent of 5 turns of normal production so we can build a wonder in about 60% of the normal build time.
All numbers used above are from memory and might be slightly out.
The sequence I use in Warlords is something like this. Assume a high food city with say 10 base hammers from tiles and a food surplus of say +14 from floodplains, grassland farms and good food tiles. Assume the wonder has been building for a few turns and gets a bonus from stone
turn n: building wonder, 10 hammers + 25% OR + 25% forge + 100% stone = 25 hammers applied to wonder
turn n+1: build horsearcher, 10 hammers + 25% forge = 12 hammers (38 remaining)
turn n+2: (whip 2 pop to complete horsearcher = 60 hammers, + 10 hammers) = 70 base hammers. Note only 31 base hammers +25% forge completes horsearcher and 39 hammers overflow.
turn n+3 build wonder, Overflow 39 hammers, +10 hammers = 49 hammers , + 25% OR + 25% forge + 100% stone = 122 hammers applied to wonder.
The net effect of the three turn sequence n+1, n+2 and n+3 is to produce a useful unit = horsearcher and apply 47 more hammers to the wonder than normal at the cost of 2 pop. With a food surplus of +14 over 3 or 4 turns we can expect to regrow the 2 pop. Under HR the horsearcher offsets the unhappiness. This sequence can be applied 3 or 4 times to speed up wonder production. In 3 turns we are getting the equivalent of 5 turns of normal production so we can build a wonder in about 60% of the normal build time.
All numbers used above are from memory and might be slightly out.

) as the unit we whip. What does the production bar tell us on each turn? On the turn where we put the Axe in the queue, it says we produce 1 hammer per turn. On the next turn, the Axe is at 1/35, and the production bar says 1 hammer per turn. Now we whip: the Axe is at 61/35, and the production bar says 1 hammer per turn. We hit end turn, and the city gives us another hammer, and produces the Axeman, and has 27 hammers of overflow. So on turn three, the production bar shows us 28 hammers per turn. The overflow hammers aren't applied to the wonder (or whatever) unless it is at the top of the production queue when we hit end turn. So the next military unit goes into the queue (with no overflow hammers available) on turn four.