232 [Senate 



a severe drougth, he admitted water in small gutters between the 

 hills and rows of vegetables in his garden. " In ten days early po- 

 tatoes grew two-thirds in size." In fact he never obtained good 

 potatoes before. Other vegetables were greatly benefitted. The 

 great increase by watering, in the growth of spinach, lettuce and 

 strawberries, by the English and Flemish gardeners, is well known. 

 In a warmer climate, the advantages would be increased. "The 

 melon," says Lindley, " acquires its highest excellence in countries 

 where its roots are always immersed in water, as in the floating 

 islands of Cashmere, the irrigated fields of Persia, and the springy 

 river beds of India." But the same experiments were not attended 

 with such success in London, where the leaves perspire less, and the 

 climate is cooler. During the past summer, raspberry plants, watered 

 by the drippings from the eaves of a workhouse, grew triple the size 

 of others deprived of this advantage. 



But as all plants are rendered more succulent by watering, the 

 supply of water should be withheld to all that bear fruit, as the pe- 

 riod of maturity approaches, or diminished flavor will be the conse- 

 quence. 



Calculating the velocity of water in channels. — It often 

 becomes a matter of some consequence, not only in cutting channels 

 for irrigation, but for surface drains in reclaiming wet lands, to know 

 the exact amount of water which may be carried with a given descent 

 in the stream. To enable any person to calculate this readily, the 

 following rule is given, and may be readily used by any boy who 

 understands common arithmetic. 



To ascertain the mean velocity of water in a canal or river flowing 

 through a straight channel of equal size throughout : 

 Let /= the fall in one English mile in inches : 

 Let d = the hydraulic mean depth ; 

 Let V = the velocity in inches per second, then 



V = 1.23vW- 



The hydraulic mean depth is a quantity, which when multiplied 

 by the perimeter of the channel in contact with the water, gives an 

 area equal to the area of the section. 



Example : Suppose a furrow is cut six inches wide and four inches 

 deep, with perpendicular sides, and that it descends one inch in a 



