104 Temperature and Saltness of the River Hugli. [March, 



The gas which had caused the blue flame seemed now all exhausted, 

 as there was not the slightest appearance of the halo which surrounded 

 the candle on its being first let down. The candle was again lowered, 

 but had no sooner reached the surface of the soil below than it was 

 extinguished. 



The appearances above described are readily explained from the 

 formation of carburetted and phosphuretted hydrogen from the decom- 

 position of the vegetable and animal matter deposited in the wells : the 

 heavy gas at the bottom was doubtless carbonic acid, formed by the 

 combustion of the inflammable gases. The object of bringing the above 

 facts to the notice of the public is to prove the great utility of the well 

 system in a town situated like Calcutta, on a flat, and necessarily un- 

 provided with common sewers. The experiment has been tried with 

 success also in the barracks at Chinsurah and in Fort William, and 

 in both the decomposition of the deposited matter is so rapid from the 

 combined influence of the temperature and water, and from the mul- 

 titude of living creatures which swarm within the wells, that there 

 would, in ordinary circumstances or where the number of people resort- 

 ing to them is moderate, seldom if ever be occasion to clean them out. 



M. 



V. — On the Temperature and Saltness of the River Hugli, from 

 Calcutta to the Sea. By G. A. Prinsep, Esq. 



Having had occasion to make frequent visits to Saugor Island, during 

 the last four years, I usually availed myself of the spring tides, for 

 greatei expedition, and it was my practice to register the temperature 

 and specific gravity of the river surface (the latter tried with a very 

 sensible hydrometer) as I passed the Fort, Budge Budge, Fultah, and 

 other principal stations both in going and returning, and especially to 

 note the degree of saltness existing at the change of tide in whatever 

 part of the river I happened to be. In this manner I have accumulated 

 above 350 observations of temperature, and nearly as many of specific 

 gravity, embracing all seasons of the year, but least copious in the 

 rainy months. They may perhaps be worth recording, to assist the 

 researches of some speculator in meteorological subjects, and to facilitate 

 comparison with other rivers. 



The following table contains a summary of the temperatures 

 observed : the blanks of July have been filled up by estimate, in order 

 to obtain a general mean. . 



