^VDDITIONAL NOTES OX TREE-TRUNK WATKR-PIPES. 235 



filthy or noxious, and fjenerally it becomes transparent in a short time, if kept 

 stilf to allow the subsidence of the particles which occasion its opaque 

 a])pearance," &c. 



As regards wells as a source of supply, our author mentions 

 them as giving but a limited and variable quantity of water, 

 which, if more "transparent" than river water, was frequently 

 much less wholesome. Thus, " the recent analysis of the trans- 

 parent water from the Treasury pump at \Miitehall shows it to- 

 contain extraneous matter to the amount of four times the 

 quantity from the Thames at Hammersmith, and the filtered 

 water from the Chelsea Works." 



It is evident that the knowledge of the geological structure of 

 London and the district around it available in 1835 was utterly 

 insufficient to allow of the sinking of artesian wells there on 

 scientific grounds. Indeed, the earliest work of authority giving 

 the geological structure of the London district, with especial 

 reference to artesian wells, is Prestwich's Geological Inquiry 

 respecting the Water-hearing Strata of the country around London, 

 ivith reference especially to the Watei'-supply of the Metropolis ; 

 published in 1851. In this work we find only one allusion to 

 Hydraulia, and that is in a note on p. 9. Prestwich is there 

 noting the names of books giving details of the construction of 

 artesian wells. He mentions but one British work on that 

 subject, adding that Matthews' Hydraulia does not treat of this 

 question. But in this case the mere allusion to a book published 

 16 years before is evidence that Hydraulia was a standard work 

 on the subject of water supply. 



My object in quoting so much from Hydraulia on the 

 turbidity and transparency of water is to bring into prominence 

 one of the influences greatly retarding the adoption of waterworks 

 in the first half of the last century, but hardly likely to suggest 

 itself to us now. It is no exaggeration to say that the views on 

 turbidity suggest rather those natural to the cook at a hotel or 

 club, who found a feeling prevailing there that all soup but 

 " clear" soup was disgusting and dangerous to health, than such 

 as might be expected on clear water from an eminent advocate 

 of waterworks. In short, we must bear in mind that shallow- 

 well or pump water had the attraction of being usually clear, and 

 that turbidity and most imperfect filtration, if any, was to be 

 expected in 1834 from a waterworks' supply. Also that water 

 from artesian wells was almost unknown for some years later^ 



