First observed microbes in rain water

September 15, 1675

In a letter the following year, 1676, Leeuwenhoek indicates that he first observed microbes in September 1675. The version translated for publication in Philosophical Transactions omits the date, so this is my translation of the original letter:

Inden Jare 1675 ontrent half September, besig sijnde met het observeren dande Lugt, wanneer ik die door het water seer geparst hadde, ontdecten ik levende schepselen in regenwater, dat maer eenige weijnige dagen in een nieuwe ton, die van binnen blauw geverft was had gestaen.

In the year 1675 close to mid-September, being busy with observing air, when I had greatly pressed it by means of water, I discovered living creatures in rain water, that had stood only a few days in a new cask, that was painted blue inside.


Letter 18 27, Oct 9, 1676