382 MY LIFE 



den (a relative of Bishop Hampden) challenged scientific 

 men to prove the convexity of the surface of any inland 

 water, offering to stake £500 on the result. It contained the 

 following words : " He will acknowledge that he has for- 

 feited his deposit if his opponent can exhibit, to the satisfaction 

 of any intelligent referee, a convex railway, river, canal, or 

 lake. " Before accepting this challenge I showed it to Sir 

 Charles Lyell, and asked him whether he thought I might 

 accept it. He replied, " Certainly. It may stop these foolish 

 people to have it plainly shown them." I therefore wrote 

 accepting the offer, proposing Bala lake, in North Wales, 

 for the experiment, and Mr. J. J. Walsh, editor of the Field, 

 or any other suitable person, as referee. Mr. Hampden pro- 

 posed the Old Bedford canal in Norfolk, which, near Down- 

 ham Market, had a stretch of six miles quite straight between 

 two bridges. He also proposed a Mr. William Carpenter (a 

 journeyman printer, who had written a book upholding the 

 "flat earth" theory) as his referee; and as Mr. Walsh could 

 not stay away from London more than one day, which was 

 f°ggy> I chose Mr. Coulcher, a surgeon and amateur 

 astronomer, of Downham Market, to act on my behalf, Mr. 

 Walsh being the umpire and referee. 



The experiment finally agreed upon was as follows: The 

 iron parapet of Welney bridge was thirteen feet three inches 

 above the water of the canal. The Old Bedford bridge, about 

 six miles off, was of brick and somewhat higher. On this 

 bridge I fixed a large sheet of white calico, six feet long and 

 three feet deep, with a thick black band along the centre, the 

 lower edge of which was the same height from the water as 

 the parapet of Welney bridge ; so that the centre of it would be 

 as high as the line of sight of the large six-inch telescope 

 I had brought with me. At the centre point, about three 

 miles from each bridge, I fixed up a long pole with two red 

 discs on it, the upper one having its centre the same height 

 above the water as the centre of the black band and of the 

 telescope, while the second disc was four feet lower down. It 

 is evident that if the surface of the water is a perfectly straight 

 line for the six miles, then the three objects — the telescope, 



