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Link: • Peter Collinson to Carl Linnaeus, 20 May 1762 n.s.
Dated May 20: 1762. Sent from London (Great Britain) to Uppsala (Sweden). Written in English.


Peter CollinsonCollinson, Peter (1694-1768).
British. Merchant and amateur naturalist
in London, corresponded with many
scientists. Correspondent of Linnaeus.
sent Linnaeus his treatise on the migration of swallows some years earlier [Collinson refers to his, “A letter to the honourable J. Th. Klein”Collinson, Peter “A letter to
the honourable J. Th. Klein, secretary
to the city of Dantzick, from Mr Peter
Collinson, F.R.S. concerning the
migration of swallows”, Philosophical
51 (1760), II, 459-464.
], but he has not heard anything from Linnaeus on the matter.

Collinson has concluded from others that Linnaeus has asserted that swallows live under water all winter, but Collinson and everybody else expected that Linnaeus would verify that from his own knowledge or that some of his pupils would do so.

As most great naturalists deny this, Collinson urges Linnaeus to prove this thesis, which seems to be contrary to nature and reason. What has been said by earlier authors must be doubted, unless undeniable proofs support it.

Linnaeus’s reputation is so great in the present age, that when Collinson has argued about how improbable it is that swallows live under water, he has heard that it must be so, since Linnaeus says so, and you cannot dispute Linnaeus’s veracity.

Collinson suggests two experiments that would go far towards determining the facts.

Collinson thanks Linnaeus for his letter of December 11, 1761 [this letter has not come down to us].

P.S. 1. Collinson describes the experiments. The first one means dissecting the birds and finding an internal apparatus that would enable them to live under water for so long.

P.S.2. The second experiments means catching a large number of these birds at the time when they usually leave in their migration, putting them in a large and wide tub filled with mud and water and leaving them there for a month or two. If they are alive after that, the fact is proved.

P.S.3. If you are sure of when they migrate, you could observe their motions to see if some of them go down into the water. Their number is so great that it could hardly be concealed. Fishermen could also drag them up again. Also, in the spring, you should be able to observe them coming out of the water, very wet, and see how long it takes them to get dry enough to fly.


a. original holograph (LS, XVII, 70-71). [1] [2] [3]


1. A selection (1821), vol. 1, p. 54-56   p.54  p.55  p.56.
2. “Forget not Mee & My Garden ...” (2002), p. 234-235 .