Wl REPORT AND CmSBBVATIOlTS ON 



same sort of evidence, although the measurements were 

 necessarily taken at different periods of the day. 



It is true that at all times, and in swollen states of brooks 

 particularly, the measurement of streams by daily gaugings, 

 although they are repeated several times a day, can only be 

 considered as a tolerable approximation to the truth. Ac- 

 cording to the height of the flood at the time the measure- 

 ment is taken, they may indicate rather more, or rather less, 

 than the average quantity. Still the observations, regularly 

 continued, will in the course of the year pretty well correct 

 each other, and the result, obtained by taking the mean of 

 upwards of seven hundred measurements of the same stream, 

 at equal intervals of time, cannot be far from the truth. 



It is probable that had rain gauges been placed on the 

 summits of the highest hills, as well as in the valleys, and on 

 elevated parts about midway of the whole rise, the returns 

 would have shown a greater fall. 



The result of observations made by Mr. Hawksley during 

 the past year in the district surrounding Bivington Pike, 

 near Chorley, from whence the town of Liverpool is pro- 

 posed to be supplied with water, confirm the accuracy of 

 the observations which have been made in the Longdendale 

 district, the nature of the ground and the character of the 

 hills being very similar in both cases. 



Mr. Hawksley found the mean rain, from gauges placed 

 in various parts of the district, varying from 430 feet to 1800 

 feet above the level of the sea, to^ be 56^ inches, and the 

 quantity of water which flowed ofi" the ground to be about 

 44 inches, leaving 12^ inches to supply evaporation, vege- 

 tation, and absorption. 



^he greatest rain-fall was found to be at an elevation of 

 about 1000 feet. 



On this point some valuable information may be obtained 

 from observations made at the Edinburgh Waterworks. 



