THE SILTING UP OF THE CEEEKS OF FALMOUTH HAVEN, 



Bt H. MICHBLL WHITLEY, C.E., F.G.S., Hon. Sec. 



At the last Monthly Meeting of this Institution, I brought 

 before the members some notes relative to the recession of the 

 tide in the valley of the Fal, and I have to call their attention in 

 this paper to a kindred subject, which although it has not that 

 halo of romance cast around it by old traditions, yet possesses 

 several elements of interest, especially to us who are all well 

 acquainted with the various beautiful branches of Falmouth 

 Haven, of which Drayton sings : — 



Here Vale a lively flood lier nobler name that gives, 

 To Falmouth and by whom it famous ever lives : 

 Whose entrance is from sea so intricately wound, 

 Her haven angled so about her harb'rous sound 

 That in her quiet bay a hundred ships may ride, 

 Yet not the tallest mast be of the tall'st descried. 



I propose then to examine in detail the various Creeks of the 

 Harbour, to compare their present condition with their former 

 one, as far as it can be ascertained, and thus to deduce what 

 changes have taken place in the course of years. 



Taking first the main branch of the Eiver Fal that flows up 

 to Tregony, I find that at and for some little distance below the 

 bridge the bed of the stream has silted up at the rate of about 

 1 foot in 30 years. The average velocity of the Fal at Tregony 

 is 210 feet in a minute, which is sufiicient to sweep along stones 

 the size of an egg. 



The drainage area of the Fal at Tregony Bridge is 26,800 

 acres, and from numerous observations I have made on the 

 discharge of streams in Cornwall, I find that the mean flow of a 

 river is on the average for the year, 100 cubic feet per minute 

 per square mile, varying between 260 cubic feet per minute per 

 square mile in February, and about 10 cubic feet per minute per 

 square mile m July. The mean flow of the Fal will therefore 

 be about 4100 cubic feet per minute, and this water highly 

 charged with silt in suspension, passes downwards until it is 

 arrested by the tidal-flow, and the mud is then deposited. 



