Constituents of Thames Mud, By Lionel 8. Beale. 3 



tions of this authority upon the diatoms of the Elbe, to those of 

 Mr. T. F. Bergin on the deposits of the mud of the Liffey,* to 

 those of Professor Bailey on the diatoms found in the Mississippi, 

 to the paper of Mr. F. C. S. Koper on the Diatomacese of the 

 Thames,! and lastly to the memoir of Dr. Bossey on ' Thames 

 Mud in relation to Sanitary Science.' $ Mr. Eoper in 1854 and 

 Dr. Bossey more recently have carefully studied the species of 

 diatoms in different parts of the river, and have shown that the 

 valves belonging to fresh-water species growing in the upper parts 

 of the river may be carried down by the tide towards the mouth of 

 the Thames, while the valves of those liviug in salt or in brackish 

 water are to be traced as far up as the tide extends. These 

 beautiful silicious skeletons so easily recognized and identified, 

 being very light, are carried backwards and forwards by the tide, 

 and are deposited on the mud-banks. They may be regarded as 

 evidence of the course taken by other light particles suspended 

 in the water of the river, and afford one of many indications of the 

 movements of the sewage. Thus we are able to show that at any 

 rate the least dense of the constituents of sewage may be carried 

 from the outfall at Barking up to the first lock in one direction 

 and below Gravesend in the other. 



It is impossible to exaggerate the importance of investigations 

 concerning the course of the sewage in the river considered in con- 

 nection with the changes effected in it by various agencies during 

 its suspension and after its subsidence as mud. That our river is 

 fouled by the presence of sewage is patent to every one, while 

 most of us feel that its state is a disgrace to our city. The serious 

 question which presents itself to Londoners, and indeed concerns 

 England, is whether this constant pollution of the river by the 

 pouring into it daily of more than 100 millions of gallons, nearly 

 450,000 tons, of sewage can be continued without increasing risk 

 to the health of the people, to say nothing of the disagreeable 

 effects on the senses of sight and smell, and the very unpleasant 

 considerations suggested by the contamination. 



Some years ago there was unmistakable evidence of the occur- 

 rence of a very nasty kind of decomposition proceeding in the 

 Thames water. The air of all the streets bordering the river was 

 polluted with offensive odours. During the last few years, however, 

 we have not been so seriously annoyed. But it must be borne in 

 mind that we have had a remarkable series of cool and wet 

 summers, favourable to excessive dilution of the sewage and un- 

 favourable to organic decomposition. What the state of things 



* ' Cooper and Busk's Microscopic Journal,' ii. (1842) p. 68. 

 t Trans. Micr. Soc. Lond., ii. (1854) p. 67. 



j 'Proceedings of the Holmesdale Natural History Club,' December 12tli, 

 1879. 



B 2 



