A VISIT TO ENGLAND 51 
references to holidays spent at the seaside (Scheveningen) and 
“in Brabant and elsewhere.” But he once, before his election, 
visited London—though this is not generally known—and 
recorded the circumstance in an unpublished passage in an 
early letter (1674). What he there says is so interesting, in 
more ways than one, that I must quote his words. In the 
course of describing some microscopic observations on the 
composition of chalk and clay, he unexpectedly adds’ : 
About six years ago, being in England, out of curiosity, 
and seeing the great chalk cliffs and chalky lands at 
Gravesend and Rochester, it oft-times set me a-thinking ; 
and at the same time I also tried to penetrate the parts 
of the chalk.” At last I observed that chalk consisteth of 
very small transparent particles*; and these transparent 
particles lying one upon another, is, methinks now, the 
reason why chalk is white. 
Tt is clear from his own words that Leeuwenhoek spent a 
holiday in England sometime during the year 1668." He came 
to London—sailing up the Thames by way of Harwich, 
Rochester, and Gravesend (after embarking probably at 
Rotterdam)—and brought a microscope with him. From this 
it seems legitimate to infer, therefore, that he was already 
engaged in his microscopic studies in 1668—at least five years 
before his first communication with the Royal Society. These 
1 Brom Letter 6,7 Sept. 1674. To Oldenburg. MS.Roy.Soc. Incom- 
pletely translated into English in Phil. Trans. (1674), Vol. IX, No. 108, 
pp. 178-182 [misprinted 821]. From this translation the passage here 
given was entirely omitted: and in the following paragraph (p. 181), where 
L. speaks of the colour of the English soil, “ die ick aldaer tusschen Harwits 
en Londen gesien heb”, his words have been altered to an impersonal 
statement about ‘‘ that, which 7s found between Harwich and London” [my 
italics]. 
2 de deelen van het krijt te penetreren MS. By this L. evidently means 
that he attempted to study the microscopic structure of chalk. No other 
interpretation—if the context be considered—appears to me possible. 
® clootgens MS. It is hardly possible to doubt that some, at least, of 
these “transparent particles” were fossil shells of Foraminifera. 
‘ England and Holland were then temporarily at peace. The second 
Anglo-Dutch War was concluded in July, 1667, and the third was not 
declared until March, 1672. 
