Moselio Schaechter

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January 21, 2010

Fine Reading: Classics from the Archives of the Royal Society

by Elio

The Royal Society announced that it has put 60 of its most memorable papers online. One of them concerns the discovery of bacteria by Antonie van Leeuwenhoek. The original paper as published in the Society’s Philosophical Transactions of 1677-1678 was entitled:

Observations, communicated to the Publisher by Mr. Antony van Leewoenhoeck, in a Dutch Letter of the 9th of Octob. 1676, here English’d: Concerning little Animals by him observed in Rain-Well-Sea- and Snow water; and also in water wherein Pepper had lain infused.

Here are two excerpts that can be expected to tickle the present day microbiologist’s mind. (Note that in the style of the time, the letter “s” looks like an “f.”)

Fourth sort

The eye of a body louse is approximately 100 µm in diameter or 104 µm3. The organisms van Leeuwenhoek saw were 1/10 that length, or 10 µm, and 1/1000 that volume, around 10 µm3. Many bacteria reach such dimensions. The movement described matches the runs and tumbles of chemotactic bacteria.

31st of may

Let’s assume he was talking about lengths. A honey bee is about 1.2 cm in length, a horse, about 250 cm. Thus, the ratio of their lengths is approximately 200x. Cheese mites are around 0.5 mm in length, thus making the organisms he observed approximately 2.5 µm long. I haven’t found out how thick the hair of a cheese-mite is.



Many thanks for the wise opinion and for pointing us to an interesting web site.


UNESCO should declare the collection of "Philosphical Transactions" World's Cultural Heritage. I like an article published in 1736, in which Hans Sloane and Thomas Birch describe smallpox inoculation. This technique was introduced in Britain by lady Mary Wortely Montagu, wife of the English Amabassador in Turkey, and Sloane adopted it. This happened some 60 year before Edward Jenner tested the first vaccine. You can see the article at

What an amazing paper because it described the discovery of a whole living world unknown to that time! There aren't many others that can make that claim.
Besides the "s" that looks like "f", I liked the phrase used for translated, "here English'd"

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