[[p. 41]] Grays, Essex, July 14, 1873.

To the Editor of the Zetetic.

     Sir,--You have sent me your issue for July, containing a mis-statement with respect to myself. I never "agreed to try the boat experiment," and had never heard such an experiment proposed till after the trial referred to.

     As to the challenge to try such an experiment, I have no hesitation in admitting it to be a conclusive one, and will cheerfully abide the result of the trial with any impartial judges to decide whether the boat continues to be seen or not. But I would not accept the dictum of any person unaccustomed to the use of the telescope, because it requires practice to distinguish between small objects at such a distance and so near the surface.

     I propose therefore that you should invite any professional land surveyor or civil engineer from the neighbourhood to decide the simple question of fact whether the boat in question remains visible at a distance of six miles under the conditions named by you, the telescope being one quite capable of rendering it visible when taken to a sufficient elevation.

     I will ask Mr. Coulcher, of Downham, to represent me, so far as to see that the experiment is fairly tried; the statement of the surveyor on the [[p. 42]] matter of fact being agreed to be accepted by us both.

     I also agree to pay half the surveyor's fee.

ALFRED R. WALLACE.

[[p.42]] The Dell, Grays, Essex,
July 25, 1873.

To "Parallax."

     Sir,--As you propose "taking with you a surveyor" without even giving me his name and address, or any references to prove his capacity and impartiality, or leaving any time for me to ascertain anything about him, I must decline being a party to your experiment.

     That is not according to the terms of my letter.

     If, however, you are disposed to submit the decision to any professional surveyor or engineer of the locality, say of Lynn or Wisbeach, I will write to Mr. Coulcher to attend on my behalf. At all events I write to Mr. C. to-day, and he will, I am sure, meet you in any fair and open arrangement to carry out the experiment exactly as proposed by you.

     If your surveyor can prove that he is a properly qualified professional man in actual practice, I should of course not object to him.

I remain, yours truly,
ALFRED R. WALLACE.

[[p. 42]] The Dell, Grays, Essex,
July 26, 1873.

To "Parallax."

     Sir,--I have sent yours of yesterday to Mr. Coulcher, and leave all arrangements to him.

     As to any "collateral observations" you may please to make, I have no part in them, but only in the one experiment you yourself have put forward as conclusive. If it is conclusive, of course, no other or collateral experiment can be of the least value.

I remain, yours truly,
ALFD. R. WALLACE.

[[p. 42]] The Dell, Grays, Essex,
July 27, 1873.

To "Parallax."

     Sir,--I have just received a note from Mr. Coulcher, saying he will act for me; but he adds, "I consider the time of year most unfavourable for the telescope, on account of vapours and the flickering of the air, especially when the telescope is so near the surface. I am quite positive that the bridge from either end, could not be defined. Late in October or early in November would be the best time."

     As Mr. Coulcher is a resident on the spot and thoroughly practiced in the use of the telescope, of which he has several excellent ones, I think you would do well not to risk seeing nothing and proving nothing by going now.

     I think it right to send you this information at once.

Yours truly,
ALFRED A. WALLACE.

[[p. 43]] The Dell, Grays, Essex,
July 29, 1873.

To "Parallax."

     Sir,--Mr. C.'s address is "M. W. B. Coulcher, Esq., Surgeon, Downham." He will be engaged next week, being subpœned to the Norwich Assizes.

Yours truly,
ALFRED R. WALLACE.