Part of a Letter from the Reverend Mr. W. Derham, F. R. S. to Dr. Hans Sloane, R. S. Secr. concerning the Migration of Birds

from whence the Head did partly discharge itself, and the Matter to be cast out, which comes into the Mouth without its proceeding from the Lungs; as also that there are a great many parts in it, which receive the Matter which we call the Taste: but this wants a further Enquiry. VI. Part of a Letter from the Reverend Mr. W. Derham, F. R. S. to Dr. Hans Sloane, R. S. Secr. concerning the Migration of Birds. Upminster, April 1st. 1708. I Remember that some time since, I promised to suggest a thing to the Society relating to the Migration of Birds, which I conceive may conduce to the Discovery of that pretty Phenomenon; and I am sorry I forgot it till the Jynx (just now come) hath brought it to my Thoughts. The Business I would humbly recommend is, That the Members of the Society all over the Realm, would themselves, or procure their inquisitive Friends to observe, and note down the very Day they first see or hear of the Approach of any of the Migratory Birds. And it may be convenient also to observe how the Winds fit at the same time, especially towards the Sea-coasts. The several Observations ought to be communicated to the Society. Which when compared together, we may probably make a good guess which way those Birds come, whether fromward the East, or any other Point. The Jynx or Wryneck (for instance) which I take to be undoubtedly a Bird of Passage, I first heard this Year on March 29, the Wind Southerly, or S. Westerly that and the preceding Day; but Easterly before. The Certhia also or Creeper (which leaveth us in Essex until the Spring, but whether a Bird of Passage I can't tell; this Bird I say) I saw first on March 23, the Winds that Day varying from S. to N. but blowing strongly the Day before from the Westward. Now if those Birds in the more Westerly, or any other parts, at 100, 200 or more Miles distance, should be discovered to come sooner or later, we might conclude, that accordingly they came fromward the East or West, or other Point, especially if about the same time the Winds seemed to favour their Flight. These are all the Migratory Birds I have seen as yet this Year. But for a farther Sample I shall annex my Observations last Year, viz. The Swallow came March 31, making a great Outcry at his Approach, as if he saw something strange. April 1, the Jynx first yelped here. April 4th, I first espied the Ruticilla or Redstart. The 5th I saw the Martin. The 6th the Nightingale first sang with us. The 7th the Cuckow I was told was heard, and the 9th I heard it myself. The 17th, I heard the Swift or Black-Martin squeek in an Hole in my House, in which it hath quietly built for several Years: But it being cold Weather, he did not fly abroad till some Days after. As to the Coast of the Winds about those times, they may (if desired) be best seen in my Tables, which I will send you, &c. LONDON, Printed for Henry Clements at the Half-Moon in St. Paul's Church-yard. MDCCVIII.