4 Transactions of the Society. 



would be if we had a very dry hot summer succeeding to a spring 

 with less than the usual rainfall it is not pleasant to contemplate, 

 for 1 am afraid it is probable that the considerable reduction of 

 the Yolume of water in proportion to the sewage would result in 

 a concentration of the dissolved and suspended organic matters, 

 which, gradually rising in temperature from day to day to 70° or 

 higher, would perhaps almost suddenly undergo a form of putre- 

 factive change resulting in the setting free of large volumes of 

 highly fetid gases, which ^ould poison the air far and wide. Such 

 a nuisance might persist for weeks, and only disappear when by 

 the autumn rains the tidal water had become greatly diluted and 

 its volume increased by fresh water pouring in from above. How 

 far such a state of the river would be injurious to health it is 

 not possible to say. I do not think anything of the kind upon so 

 large a scale has ever happened, and any suggestion as to possible 

 danger to health, not being backed by actual facts, would only excite 

 counter observations and assertions as to the excellent health enjoyed 

 by those who spend much of their time in the sewers, and a review 

 of facts, carefully selected by no impartial hand, with the object of 

 convincing people that stinks were not unwholesome, and that 

 possibly to the trained they might be actually enjoyable ; that 

 the presence of decomposing animal and vegetable matter sus- 

 pended in water was rather an advantage than otherwise ; that 

 countless multitudes of harmless organisms while ministering to 

 their own enjoyment and advantage, exerted a beneficent influence 

 by appropriating the products of disintegration just prior to decom- 

 position ; and that upon the whole we ought to consider ourselves 

 fortunate in possessing in our midst a large river reeking with 

 filth, because in this way the noxious substances are slowly re- 

 solved into simpler gaseous and soluble matters instead of the 

 whole contributing to increase the already sufficiently ample mud- 

 banks, which — and at a constantly accelerating rate — would add to 

 the difficulties of navigation, and at length interfere with the 

 passage of all but the smallest craft. 



Method of Examination. 



The large amount of gritty silicious particles, as well as their 

 considerable size, renders the examination of small portions of mud 

 just as it is obtained from the mud-bank very difficult. The layer 

 placed on the glass slide and covered with thin glass will be too 

 thick for examination by any but the lowest powers, and in con- 

 sequence, some of the most minute but most important of the 

 constituents of the mud will not be discerned. If a little of any 

 specimen of mud be mixed with water, covered with thin glass, and 

 then examined in the usual way, nothing but large sand-grains. 



