32 



Proceedings of the 



test, because I am better acquainted with them than I am with the other 

 minute organisms found iu Thames mud, and because, to use the words 

 of Mr. O'Meara, "some species are found only in fresh water, some only in 

 salt, and an experienced observer will be able at a glance to ascertain 

 whether a gathering is marine or made iu fresh or brackish water." Tested 

 in this way, I find that mud taken half a mile above Teddington Lock 

 contained 66 species of fresh watei and no marine Diatoms. Another 

 sample of mud, one mile below Teddington Lock, had 54 fresh water and 

 no marine forms. A sample taken at Kew, five miles below Teddington 

 Lock, had .52 fresh water and 37 marine forms. Another taken at Blackwall 

 had 39 fresh water and 45 marine forms. In the face of such facts, I think 

 it will be no presumption on my part to say that the study of the natural 

 history of the Thames mud aflEords important evidence in the support of the 

 position taken by the Conservators of the Thames, and I may add that the 

 possibility of the facts of natural history being thus applied in such an 

 unpromising field is only additional proof that all knowledge is useful, 

 when occasion offers for its application. 



The following table presents the respective numbers of fresh water and 

 marine Diatoms found in the mud from the various localities : — 



Fresh water diatoms 

 Salt water diatoms 



Mr. Tyndall read a paper on the subject of " The Extent of the Prospect 

 from Reigate Hill," as follows : — Most of us, perhaps all, have often 

 surveyed the beautiful, extensive, and varied prospect from Beigate Hill 

 without regard to the extent of the prospect under view. It would be very 

 interesting to have an account of the various places of interest to be seen 

 from that elevation ; but an account of all these, and of the geological 

 formations within view, would require a volume, and not a paper merely, 

 and would take hours to peruse instead of minutes. The object of 

 this paper is to indicate the extent of prospect within view ; and this limited 

 subject may be new to some, while T trust it may be of interest to all. By 

 Eeigate Hill I do not mean one standpoint only, but the line of hill, taking 

 it from the Suspension Bridge, through the beeches, to the knoll at the west 

 end of the hill, over the old road to Walton Heath. Commencing our walk 

 from the Suspension Bridge, along the lane westward towards the grove of 



