228 



The Primary Upheaval of the 



causing the thread attached to the ball to form with the ver- 

 tical an angle of from twenty to thirty degrees. 



Denoting by B the coefficient corresponding to that ball, 

 and by S the observed angle^ the surface velocity was found 

 by the ordinary formula X = 0 



I have known cases where engineers^ with a mere know- 

 ledge of the fall per mile in a river^ and the sectional area, 

 taken at one point only, have, from such very insufficient 

 data, endeavoured to compute the discharge. For the usual 

 formula, by Eytelwein, from which have been derived the 

 tabulated quantities in Bcardmore's Hydraulic Tables, and 

 other works, is only applicable under the following condi- 

 tions, which never occur unless in carefully constructed arti- 

 ficial channels : viz. 



Unchanging sectional area. 



Unchanging wetted perimeter. 



If on the length corresponding to the fall, a great number 

 of cross sections had been taken, so as to admit of a mean 

 sectional arca^ and mean perimeter of the water contour being 

 deduced therefrom, then of course a rough approximation to 

 the discharge could have been computed. 



Many instances might be cited of disappointment attendant 

 on the completion of hydraulic works, owing to the prelimi- 

 nary calculations having been made on erroneous principles. 

 For instance, when the works for conducting water into 

 Edinburgh were completed, the quantity of water delivered 

 was only one-sixth of the quantity estimated by the designer 

 of the work, although he himself acknowledged that the 

 work had bee# executed in strict accordance with his plans. 



Art. XIX. — On the Primary Upheaval of the Land round 

 Melbourne, and the recent Origin of the Gypsum or Sul- 

 phate of Lime in the great swamp between Batman s and 

 Emerald Hills, Flemington, Williamstown, and Melbourne, 

 illustrated by a large number of Specimens from that Locality, 

 By William Blandowski, Esq. 



The land which now constitutes the colony of Victoria 

 owes its origin to the same mighty convulsion which upheaved 

 the Australian Alps. Beginning where those mountains cross 

 the latitude of 37°, eruption followed eruption in rapid suc- 

 cession, the plutonic agency constantly advancing westward. 



