Sir,--Mr Hampden has sent me your paper of the 16th inst., containing a long letter from himself, in which he gives your readers to understand that I have refused his offer of a second trial for £1,000. This, like many other of his statements, is recklessly false; and I challenge him to publish, entire and verbatim, in your columns, my letters to him of March 20th and March 26th, accepting his challenge and his own tests. If he refuses to do this, or to apologise for making so false a statement, I warn your publisher that he lays himself open to an action for libel by admitting letters charging myself and Mr Walsh with swindling.

Alfred R. Wallace.
London, April 18th, 1870.

     [If Mr Hampden was good for £500 on the test bet, why should he not be threatened with law if he libels? It is very hard, unquestionably, to suggest that the experiment as to the convexity of the water was "a swindle." The £1,000, the Field's editor says, has been paid over to Mr Wallace. Yesterday morning we received Mr Hampden’s pamphlet, entitled "Is Water Level or Convex After All? The Bedford Canal Swindle Detected and Exposed." In that publication Mr Hampden publishes a number of Mr Wallace's letters addressed to him, and extending from January to March.—Ed.]