ai Hobart Town, %Q)th and '21th Fehruary, 1854 3 



from such a survey, for the quantity discharged into the 

 creek at the different points would vary in proportion to the 

 greater or less slope of the ground, and the solution of the 

 problem would therefore be so complicated as to be practi- 

 cally useless. 



It is, however, possible to arrive at an approximation to 

 a mean area, in a much shorter, simpler, and, with relation 

 to the subject under consideration, a much more accurate 

 way, by ascertaining the quantity of water passing through 

 the creek at a given spot during any period, say an hour ; 

 and assuming this to be the amount which fell during a 

 similar period antecedent to that at which the experiment is 

 made, it is obvious that in this manner some practical 

 result could be arrived at, by which the area of drainage 

 could be ascertained with every necessary degree of accuracy. 



At present we are not in possession of any accurate 

 observations by which the quantity of water passing 

 down the creek, at any given period, can be estimated ; 

 under such circumstances the following approximation 

 may be admitted rather as indicating the mode of arriving 

 at the area, than as affording more than a guess at its 

 dimensions. 



Levels and sections of the rivulet were taken at two points, 

 one above Wellington Bridge, and the other above the Bridge 

 in Campbell-street; the depth of water in these sections was 

 assumed from my recollection of its height at the points 

 in question, on Monday, February 27th, about If a.m., 

 when the obstructions at these bridges were cleared away : 

 from the elements thus obtained, it would appear that the 

 velocity of the current above the Wellington Bridge was 14'3 

 feet per second, and above the Campbell-street Bridge 9*6 

 feet per second, and the quantity of water discharged per 

 hour at the former was 5559840 feet, while th« quantity 



