Difference of Level between the Sea and River Thames. 187 



Hydrocyanate of Ammonia. 

 Berzellus NH'Hc^N 



Whewell (n + 3H) + (2cTn + li) 



Proposed System... (3H). + [2c). + H' 



Persulphate of Iron and Potash. 



Berzelius 2S U Fe +S K +25 H 



Whewell 2(HS+4io+fe+io) + CS+30+Ka+o)+25(h+o) 



Proposed Syst. 2( 1 -| S" + Fe ' ) + S" + Ka) + 25 H' 



Ferrocyanate of Potash. Cyanate of Lead. 



Berzelius... 2c-NK + eNFe + 3H C'NoP.b 



Whewell 2(Ic+n+K) + (2c+n+Fe)+3Ch + o) (2c-fn + o)+(pb + o) 

 Prop. Syst. 2((2c).+K) + ((2c).+Fe)+3H (2C).+o+Pb' 



Ammoniacal Alum. 



Berzelius 3al S" +NH^S"^ 



Whewell 3(al + o + s + 30) +(n + 3h + s + 30) 



Proposed System... 3(al + S") + ((3H). + S ') 

 30, Church-street, Spitalfields, July 1832, 



X L. Tabular Abstract of the Results of Capt. Lloyd's Leveling 

 from the Sea near Sheer?iess to the River Thames at London 

 Bridge. By B. Bevans, Esq. 

 To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



CAPT. LLOYD'S paper, as published in the Philosophical 

 Transactions for 1831, which shows thatth.e brass standard 

 at the landing-place of NewLondon Bridge is 2-3967 feet below 

 an arbitrary mark atSheerness, contains little information rela- 

 tive to the longitudinal section of the river Thames itself, either 

 as to the surface of the water at high, mean, or low state; and 

 which, in a philosophical point of view, would hive been very 

 interesting*. Most tidal rivers have the high-water mark at the 

 outlet considerably higher than at a distance of some miles up 

 the river, particularly when the country is flat, or almost level, 

 through which the river passes ; whereas it appears by these 



• An abstract of Capt. Lloyd's paper, iiichuliri!; a brief account of the 

 apparatus and iiicihods employed, was s^ivcn in Phil. Mag. and Annals, N.S., 

 vol. ix. 1). '.Vu . — Edit. 



2B2 



