HALIFAX WATER WORKS. JOHNSTON. 85 



with an area of 16 acres. The run-off from this water-shed has 

 never been measured, although some measurements of the flow 

 from the Bayer's Lake portion have been made, and the cal- 

 culation of its yield has to be made from the rainfall. In 

 estimating the capacity of the gathering grounds there must be 

 considered the extent and character of the drainage area, the 

 average and minimum yearly rainfall, the distribution of the 

 rains through the various months of the year, the average and 

 least percentages that are carried by the streams, the storage 

 capacity that can be secured and the evaporation from the sur- 

 face of the area. 



The slopes of the drainage area of Long Lake and Chain 

 Lake are steep, and consist chiefly of rock formation with 

 scanty soil and not very much vegetation. The rainfall is 

 measured by the Dominion meteorological agent in the city of 

 Halifax, arid at the lakes by the city water department. The 

 gauges at the lakes are set in such a position that they should 

 measure accurately the precipitation. The average yearly rain- 

 fall in the city of Halifax, from 1869 to 1905, is 56 inches 

 and the minimum 45.808 inches in 1894. In Mr. Keefer's 

 report of 1876 the rainfall for the years 1859 to 1865 is giveTi, 

 and during' this time a minimum of 39 inches is recorded for 

 1860 and an average of 51.62 inches for the seven years. It is 

 not known by whom these records were made. 



The writer is unaware of any studies to determine the 

 evaporation having been undertaken in Nova Scotia, but the 

 generally accepted rule here is to allow that one-half the rain- 

 fall will be lost from this cause and all that falls on the water 

 surface of the drainage area. In his opinion this would cover 

 the loss on the low service water-shed as there are few swamps 

 or shallow places where the water lies, and as before mentioned, 

 the slopes are fairly steep. In fact, taking the area of the 

 water-shed, the amount flowing over the waste weirs, the 

 amount estimated to be delivered in town, the loss from leak- 

 age at the dams and the amount delivered to the mill owners, 



