LETTER 18. 9 OCTOBER 1676 TL 
[1st Observation on Rain-water. | 
In the year 1675, about half-way through September ' 
(being busy with studying air, when I had much compressed 
it by means of water”), I discovered living creatures 
in rain, which had stood but a few days® in a new tub, 
that was painted blue within.* This observation provoked 
me to investigate this water more narrowly; and especially 
because these little animals were, to my eye, more than 
ten thousand times smaller’ than the animalcule which 
Swammerdam ° has portrayed, and called by the name of 
from Oldenburg’s, nor yet to point out all his many minor omissions. 
These will be manifest to anybody who will take the trouble to compare 
this rendering with that in the Phil. Trans. Only important errors, 
interesting variants, or vital omissions, are indicated in my notes.— 
Vandevelde (1922, p. 348) numbers this letter ‘ [15] Brief Tr. 11,” but it 
certainly cannot be called ‘‘ Letter 11” or 15” in any sense.—The letter 
is not to be found, of course, in either the Dutch or the Latin edition of the 
collective works. 
* In den gare 1675 ontrent half September MS. “In the year 1675” 
Phil. Trans. By neglecting to translate the latter part of the original 
statement, Oldenburg left the precise date of the discovery in doubt; and 
a controversy arose later between Ehrenberg and Haaxman in consequence— 
the former alleging that the observations were made in April, while the 
latter, on evidence furnished by the MS. letter from L. to Const. Huygens, 
believed the correct date to be mid-September. Cf. Haaxman (1875). It 
is now obvious that Haaxman was right. 
> Some account of L.’s experiments “on the compression of the air” 
had already appeared in Phil. Trans. (1673), Vol. IX, p. 21. (Letter 2, 
15 August 1673. MS. Roy.Soc.) 
* “four days”’ Saville Kent (Vol. I, p. 3). This is merely due to careless 
copying, and is not in the originals. 
. . . . be 
* in een nieuwe ton, die van binnen blaww geverft was MS. in a new 
earthen pot, glased blew within’ Phil. Trans. Oldenburg here mis- 
translated L.’s words, which were quite plain and were rendered concordantly 
by Chr. Huygens “dans un tonneau peint en huile par dedans’”’. The vessel 
was obviously not of Delft porcelain. 
° ¢.e., in bulk—not in diameter. This expression means, with L., that 
he judged the animalcules to have roughly one twenty-fifth of the diameter 
of the bigger creatures. 
® Jan Swammerdam (1637—1680). For his life see especially his 
Biblia Naturae (1737) and Sinia (1878). 
