How they moved a house

The long version, for anyone who wants the whole rig. A companion to Four Housepower.

Labelled diagram of a nineteenth century house-moving rig: the house on greased runners over rollers, a plank track ahead of it, a capstan anchored in the street, and a horse walking a circle at the end of the sweep.
Drawn for the post, from the 1909 Woodstock photograph and Knight's 1876 figure.

The rig, in order

  1. Dig it out. A trench around the foundation, deep enough for a man to stand in, and enough of the underpinning taken out to get at the frame. Nothing else can happen until it is dug out, because until then there is no way to reach the sills at all.
  2. Jack it up. Screw jacks go under the sills, a great many of them, and each one is turned a quarter turn at a time so the whole frame rises level. Turn one too far and the frame racks and the plaster goes. Nothing can go underneath the house until it is hanging in the air.
  3. Slide the runners under. Long timbers laid fore and aft, greased, take the weight off the jacks and become the sled the building rides on.
  4. Rollers across. Under the runners go rollers, lying crossways. A roller travels at half the speed of the load above it, so they squirt out at the back, and men carry them round to the front all day. That single fact is why a move was measured in feet per day rather than miles.
  5. Lay a track ahead. Planks and crossties down the road in front of the house, a railroad about as long as the building itself, taken up behind and carried forward all day, so that it travels with the house.
  6. Set the capstan. A ship's windlass brought ashore: a vertical drum in a heavy timber frame with a long arm, the sweep, sticking out of it. It is planted in the roadway well ahead of the house.
  7. Anchor it. Posts driven into the ground and chained to the frame, or the nearest big tree, because the capstan has to pull against something that will not move.
  8. Reeve the line. A block is bolted to the front of the house. The cable runs from the drum out to the anchor, back through that block, and onto the drum. Every extra part of line through the blocks multiplies the pull again.
  9. Walk the horse in a circle. Not toward the house. Around the capstan, at the end of the sweep, changing heading with every step.
  10. Leapfrog. The cable runs out to the anchor and back through the block, so the house creeps forward only half as far as the rope winds in: a drum carrying a hundred and fifty feet of rope moves the building about seventy-five. By then it has crept up to the capstan, and the capstan and its anchor are pulled up and reset further along, and it all starts again. The walking is the quick part. At the pace Knight's gives for a horse on a sweep, those seventy-five feet take about ten minutes. They are not ten continuous minutes, either. The pull halts over and over while men carry the rollers from the back round to the front and shift the plank track ahead. The jacks, by this stage, did their work days ago.

Why one horse is enough

This is the part I had to learn, and it comes out of two numbers that have nothing to do with how strong a horse is.

First, the building is not as heavy as it looks, once it is rolling. A house sitting on greased ways over rollers needs a pull of roughly one percent of its own weight to keep moving. Two hundred tons of house therefore asks for something on the order of two tons of pull. Enormous by the standards of one animal, but it is no longer two hundred tons.

Second, the capstan is a machine for turning a small steady pull into a large one. A horse pulls about a tenth of its own weight all day without distress, call it a hundred and fifty pounds. If the sweep it walks is fifteen times longer than the drum is thick, that hundred and fifty pounds comes off the drum as better than a ton. Reeve the cable back through a block at the house and it doubles again.

So the two numbers meet. One horse walking in circles is worth roughly two tons of pull, and two hundred tons of house on rollers needs roughly two tons of pull. That is the whole answer to the photograph, and it is why a team hitched straight to a chain is the wrong way to do it: forty animals pulling in a line are still only forty animals, while two on a capstan are multiplied by the machine.

The figures above are arithmetic of the usual orders of magnitude, not a quotation from a nineteenth century contractor. The sourced version of the same point is plainer: with a capstan and blocks, the accounts say, a team of generally no more than two animals was required.

Three things that make it real

  1. Winter helped, when they could get it. Frozen ground carries a load and greased runners slide on snow, which is why a good number of the surviving photographs are snow scenes. It was a preference, not a rule. Plenty of moves happened in the dry months, and the Woodstock photograph at the head of the post is one of them: full leaf, bare dirt, and a street you could raise dust on.
  2. It cost real money. One church move in the 1890s ran to nearly a thousand dollars, on the order of thirty thousand today. Still cheaper than building again, which is the entire economic point of moving a building at all.
  3. Speed was never the object. Feet per day. Families often stayed in the house while it traveled, with the chimney still smoking.