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Evidence & Experiment Three-Bedford Level

Bruce Williamson's picture

In 1872 Samual Rowbotham (1816-1885) wrote in "Earth Not a Globe", a nice preface that you should read if you have time. It shows that he honestly reports what he sees and is unlikely to be a fraud.

Bedford Level Experiment

A round, globe-type Earth should have curved surfaces, especially of standing water. Some math can show that any "level" surface would drop off about 8 inches in the first mile. The second mile should put the water surface 2.7 feet below the horizontal line through the starting point. The third mile, 6 ft and by the sixth mile, 24 ft. Sam tested this on a very long, very straight canal called the Bedford Level.

Bedford Level (a canal): "The water is nearly stationary--often completely so, and throughout its entire length has no interruption from locks or water-gates of any kind; so that it is, in every respect, well adapted for ascertaining whether any or what amount of convexity really exists."

Sam waded into the water at Welch's Dam (which was really just a Ferry crossing with no dam at all) and held a telescope 8 inches over the surface while another man in a boat rowed away from him, all the way to Welney Bridge six miles away.

The boat had a flag that was 5 feet off the water surface.

The man in the boat was told to raise his oar to touch the top of the bridge when he got there.


Six miles away the boat should have been riding on a water surface that had dropped 24 feet. It should have been below the horizon when viewed from such a low position. Even the tip of the flag should have been 19 feet below the horizontal. Rowbotham points out that the scope would be pointing slightly downward, since the horizon of a curved Earth would be 8 inches lower after the first mile. Calculating this way the tip of the mast still should have been about 11 feet below the horizon.

Result: Sam reported that he could see the entire boat, flag and all, for the entire distance until the man touched the bridge with the oar. He also reported the summer weather was sunny and clear that afternoon. He even writes about the possibilites of refraction causing an illusion or mirage and points out evidence that makes such an event unlikely.

What does this mean? Remember that your point of view is from that time period. You have not seen Earth from space. No-one has flown in a plane. Write yout thoughts in your log.

scanned at, June 2005. Proofed and formatted by John Bruno Hare. This text is in the public domain in the United States because it was published prior to 1923. These files may be used for any non-commercial purpose provided this notice of attribution is left intact in all copies.

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yarrum's picture

So let me see if I understand

So let me see if I understand correctly. When boats seem to disappear over the horizon, that is because the sea is curved. But when boats don't disappear along the Bedford canal that is because the canal is curved but refraction exactly cancels the curvature out. But if I look through a telescope towards the boat that just went Over the horizon or around the curve of the sea, it comes back into view as if the sea is really flat after all. But then that must be because the sea is really curved but the atmosphere has refracted the light so that it exactly cancels out the curvature. So I could ask why the boat that goes down the Bedford canal doesn't seem to disappear, like the boats that we are told go below the horizon round the curve of the earth. I could also ask what causes the apparent coincidence that causes atmospheric refraction to exactly cancel out the curvature of the earth so that it looks flat. Can anyone shed any light?

Serendip Visitor's picture

@So let me see if I understand Submitted by yarrum (guest)

The view of the boat that goes over the horiozn is enlarged by a telescope but DOES NOT reappear. You might see some of its upper deck if it has not progressed fully over the curve, but the ONLY way you can see it again is if you raise your viewing point. You can do this by climbing a hill, or by going up in a building.
If you try to view the ship with binoculars or a telesccope from your standard eye height, you do not see any extra of the ship that went below the horion. Go to the sea with binoculars and try it yourself.
It will only reappear if you raise your viewing point.
The reason for this is that you are trying to view the boat while the refracting conditions are the same for your eyes and for the telescope or binoculars

Chris's picture

Bedford level

How about a th programme re doing the Bedford level experiment using modern technology and hosted by say Tony Robinson or even Brian Cox ? It would make great viewing wouldn't it ?

Serendip Visitor's picture

Lack of controls in experiment, invalidating it

Atmospheric refraction was long known to happen and observed, even back in Rowbotham's day, but he failed to put in any controls to make sure what he was seeing wasn't being caused by this, and it seems he did this on purpose - he certainly has past form of fudging his calculations and experiments to get the result he wanted.

Alfred Russel Wallace would later repeat the experiment, taking up a wager from John Hampden, this time WITH controls - using 3 markers of equal height above the water, spaced 3 miles apart from each other, and viewing them through a theodolite.
He found that the middle pole rose up by around 32 inches - as confirmed by both his referee and the flat Earth referee.
Indeed, everybody who has ever repeated this experiment at the Bedford level has found the exact same 32 inches result, proving that the Earth isn't flat and that the water is following the curvature of the Earth.
Unable to cope with the result, Hampden refused to pay up and even threatened Wallace's life.

Also unable to cope with this result, Lady Blount decided to redo Rowbotham's original experiment, stripping away all the controls Wallace had, and petulantly claim that she had proved the Earth is flat.

Every experiment using sight lines has always returned the same result - the Earth isn't flat, and atmospheric refraction is responsible for the phenomenon.

Bill's picture

Except the agreed upon

Except the agreed upon referee was not present and instead an opium dealer was instead substituted as a witness.

Now what we need to measure is the rate of refraction predicted and seen by Wallace. Which I believe will be very different than what he claimed.

What is the standard rate of refraction for the atmosphere Wallace used for his calculations.
There isn't one? Well isn't that handy that he predicted the exact amount of refraction on a guess.

It's like magic.

Serendip Visitor's picture

Sluggish Slope

It would seem that 24 feet in six miles, is very little slope: only 4 feet or 48 inches per mile, or just under a hundredth of an inch per foot. Water with so little slope would surely be sluggish, indeed, and would appear not to move at all, though it would raise the boat up, keeping it in sight, just as the gentleman described it - provided that he was looking upstream, of course, and not downstream. Was he? It would make quite a difference. (Elsewhere I've read that refraction would explain the observation adequately, within the round earth viewpoint, but I don't know the equations for that...)

Bill's picture

Please send me whatever you

Please send me whatever you are smoking.