186 LEEUWENHOEK AND HIS “‘ LITTLE ANIMALS” 
Henshaw, Sir Christopher Wren,’ Sir John Hoskyns,° 
Sir Jonas Moore,‘ Dr. Mapletoft,? Mr. Hill,® Dr. Croune," 
Dr. Grew,* Mr. Aubrey,’ and divers others; so that there 
was no longer any doubt of Mr. Leewenhoeck’s discovery. 
Leeuwenhoek’s next communication on the “ animalcules’’ 
in infusions was sent to Robert Hooke, and is very brief; but 
it was accompanied by a copy of a very curious and interesting 
letter which he had previously written to Constantijn 
Huygens. In the letter to Hooke he says: 
As I see and hear that you are a man much given to 
speculation, I have thought fit to send you a copy of a 
very rough calculation which I set down on paper at 
the urgent intreaty of Mr. Constantijn Huygens van 
1 Thomas Henshaw (1618-1700), barrister and author: Vice-President 
and an original Fellow of the Society. Cf. Dict. Nat. Biogr. 
* Christopher Wren (1632-1723), artist and famous architect—soon to be 
President of the Society (1680)—too famous to need further annotation. 
* John Hoskyns (1634-1705), barrister of the Middle Temple: later 
Secretary and President of the Society. Cf. Dict. Nat. Biogr. 
* Jonas Moore (1617-1679), mathematician and surveyor. Elected F.RB.S. 
in 1674. He is several times mentioned by Pepys in his Diary, and his life 
is given in the Dict. Nat. Biogr. 
* John Mapletoft (1631-1721), M.D. and D.D., of Trinity College, 
Cambridge. Elected F.R.S. in 1676. He was an intimate friend of John 
Locke, and before he became a divine practised medicine in London with 
Sydenham. 
* Abraham Hill (1635-1721), Treasurer of the Society, and an original 
Fellow. Commissioner of Trade in 1689—a business-man of no known 
scientific attainments. 
” See p. 48, note 2, supra. 
* See p. 168, note 4, supra. 
* John Aubrey [sew Awbrey] (1626-1697), the well-known antiquary ; an 
original Fellow of the Society. 
* From Letter 29a. 16 January 1680. MS.Roy.Soc. An English extract 
from this letter—and its enclosure—was published in Derham’s Philos. 
Expts. & Obss. of R. Hooke (1726), p. 55. (The letter is there incorrectly 
dated Jan. 6.) I translate from the Dutch original—A contemporary 
English MS. translation is preserved with the original Dutch MS. in the 
Roy. Soc. collection, but it has given me no help. The letter was read at 
the meeting of the Society on 22 Jan. 1680 [0.S.], and discussed at the 
following meeting on Jan. 29. See Birch, Vol. IV, p. 5. 
