EAINFALL AND FLOODS. 27 



disastrous floods have been produced, I think we might 

 possibly be in a position to check in a rough way the con- 

 clusions of the engineers. 



It is in this sense that Mr. McCurrick's observation, 

 already referred to, seems to me particularly valuable. 



On the 19th of October last we were no doubt on the 

 verge of a flood, and a flood we should have had but for the 

 vigilance of the Docks engineer in lowering the level of 

 the water in the Floating Harbour as the tide in the Avon 

 permitted. Between 7 p.m. and 9.45 p.m. on that day — the 

 interval during which the sluices of the Floating Harbour 

 were closed on account of the tide in the Avon having 

 risen above the level of the water in the Float — the level of 

 the water in the Float was raised by the discharge from the 

 Frome to the extent of 3 feet 6 inches. Mr. McCurrick, 

 knowing the area of the Floating Harbour, was able to 

 calculate that the entire quantity of water so discharged 

 in 2| hours amounted to about llf million cubic feet. The 

 rate of discharge was uniform during that interval of time, 

 and that rate was the maximum rate, because the river 

 Frome was then at its maximum height. This maximum 

 rate was 4 3 million cubic feet per hour. 



Kow what were the conditions of the rainfall which pro- 

 duced this maximum rate of 4*3 million cubic feet per hour ? 

 I have already said that they were not such as to furnish 

 a crucial experiment, although they were in some respects 

 very exceptional. They may be gathered from an inspection 

 of the table on next page. 



The rainfall specially concerned in producing a state of 

 things so near to a flood was that which is set down to the 

 four days from the 16th to the 19th of the month. The 

 sum of the falls on these four days was 2'8 inches. But in 

 considering rainfall with reference to flood it is necessary to 



