84 S. R. Elson — Changes in Sea water. [Feb., 



The following papers were read — 



1. On the observed changes in the density of the surface Sea water, 

 coincident with, and due to, aerial disturbances, and consequent alterations 

 of baric pressure over adjacent sea areas. — By S. R. Elson, Bengal Pilot 

 Service. 



(Abstract.) 



In tliis paper the author shows, by means of tabulated serial obser- 

 vations since taken, that a statement he wrote in his Sandheads 

 Sailing Directory some years back, that ' the waters at the Hooghly Pilot 

 Station contained, in the dry season of the year, more salt at low water 

 than at high water,' requires some modification of the seeming paradox, 

 on account of some rather novel facts, which he has brought to light by 

 means of a common soda-water bottle hydrometer, which is capable of 

 easily testing the fluid specific gravity to the sixteenth of a thousandth : 

 — that, when a baric depression over the sea to the south, induces, as it 

 always does, an accelerated flow, or set of the sweet waters flowing out of 

 the great eastern mouths of the Ganges, over the tails of the outlying 

 sandy reefs, the specific gravity of the water at the Hooghly Pilot 

 Station being thereby consequently lessened, there is a greater com- 

 parative difference at such times between the specific gravity of the 

 waters outside of, and on the tails of the reefs, and that of the inshore 

 waters of the litoral : — a difference sometimes amounting to as much 

 as is P020 to P024. This difference the author attributes to the 

 shelter, from the above-mentioned induced accelerated incursion of 

 the sweeter eastern waters, afforded by Saugor Island and its outlying 

 partially dry sand ; and from the fact, as stated in a companion paper to 

 the present one by the author, read before this Society and published in 

 its Proceedings in November 1885, that but very little of the Hooghly 

 River water finds it way to those more sheltered positions,- to interfere 

 with the copious evaporation, which must be ever active on those warmer 

 inshore and muddy waters. 



The author also shows by means of tabulated two-hourly serial 

 observations made in November last whilst on his trip to and from 

 Rangoon, during an interval of only eight days, the very marked effect 

 which different states of weather in the Bay have on the surface 

 temperature and density curves at, and off the Pilot station, also for 

 some distance out into the blue water of the Bay, and the general 

 usefulness to mariners and others, which would be the outcome, if 

 a more exact measurement of the sea-surface specific gravity were taken 

 and published, than is now generally observed by those willing observers 

 who keep such registers ; more especially near coasts, and off the mouths 



