86 



Mineralogical Description of the Island of 



with each other ; but when the diameter was about half-an-inch, 

 they more nearly corresponded. 



I give the following from among many : 



Jet, 



Jet, 



Jet, 



Pressure 



Square 

 root of 

 Pressure. 



Consum't 

 by Metre. 



Consumpt 

 by Calcu- 

 lation. 



2 2 



33 

 44 



Differ- 

 ence. 



4 



8 

 16 



2 



2-82 

 4 



2 2 



3 3 



4-8 



26 

 36 i 



5-8 



• ■ • 



• • • 



0-4 



6 



12 



1-73 



2-6o 

 0-47 



2 82 



4 



2 6 

 3-D 

 5-2 



• • • 



0-3 

 0-4 



8 

 16 



7-01 

 10-511 



7-01 

 9-92 



0*59 



50 

 100 

 200 



7-07 

 10 

 1414 



5 07 

 7 06 

 9-64 



5 07 



707 

 1014 



0-01 

 0-50 



The following are the results with different kinds of burners, 

 the trials having been conducted with the view of ascertaining 

 the illuminating power by these burners : 



Small Fishtail, 



\ 



34 

 7 



Large Fishtail, 



Lame Fishtail, 



4* 

 97 



5-83 

 879 



6 92 



9 64 



50 

 70 



Large Batvving, 



70 

 140 



707 

 ^•36 



1-41 

 2 16 



2 27 

 33 



t • 



2-13 



03 



8-36 



11-8 



2-2 



85 



32 



■ • 



0-1 



26 



:m 



4-5 



• • • 



4-37 



• • 



01 



• • 



013 



as 



From the above it will be seen that the escapes are very nearly 

 the roots of the pressures. 



(To be continued.) 



Art. IX. — Mineralogical Description of the Island of Banka ; 



by Thomas Horsfield, Esq.,M D.* 



After the foregoing geographical description of Banka, I pro- 

 ceed to a connected narrative of the mineralogical features, in 

 order to explain the constitution of the mines, and to throw some 

 light on the geological history of the island, reserving the most 

 obvious conclusions and reflections until the observations made 

 in different parts of the island have been detailed, and may be 

 taken into one point of view. 



But, for the purpose of elucidating the following descriptions, 

 it is necessary to make some remarks or positions of a general 



nature. 



From the Joum. of the Indian Archipelago and Eastern Asia, vol. iii, No. 

 vii, 1848, p. 393. The article cited, follows a detailed geographical description of 

 the bland. est 





