WATERING THE PARKS. 



43 



each otlier. The effects of these tubes or hose have been 

 carefully studied. The following is a table of results with 

 a twelve metre apparatus^ the inner diameter of the nozzle 

 of the branch being 0-012 metres, or rather less than half 

 an inch, and the branch itself being held at an angle of 

 45 deg.: — 



Pressure at the 

 surface. 



Quantity of water 

 given per second. 



Extent of the 

 jet. 



Quantity of water 

 given when the 

 branch is not on. 



Metres. 



Litres. 



Metres. 



Litres. 



8 



0-90 



10 



1-SO 



12 



1-25 



12 



2-40 



15 



1-40 



14 



2-75 



20 



1-60 



15 



310 



26 



1-80 



15 



3-40 



30 



1-90 



15 



8-60 



85 



2-00 



16 



3-80 



46 



210 



16 



4-00 



These results, it is stated, are averages, for some appa- 

 ratus give superior or different results, although all the 

 conditions appear the same. Experience shows that with 

 the same amount of pressure in the pipes the extent of the 

 jet is enormously reduced by the lengthening of the hose. 

 Of course the diameter of the nozzle of the branch depends 

 on the pressure within the tubes, but it was thought neces- 

 sary to have a uniform model, and 0'012 metres was adopted 

 as distributing the water most advantageously with a pres- 

 sure of eight to fifteen metres. An apparatus twelve metres 

 long, with a branch one metre in length, and giving an 

 average jet of twelve metres, is effective over a radius of 

 twenty-five metres. The plugs or hydrants are placed at 

 intervals of thirty metres on roads twenty metres wide, and 

 forty metres apart in narrower roads, when they are all on 

 one side of the road. 



Formerly all the roads in and about Paris were watered by 

 means of carts which held one ton of water. It required 

 twenty-four tons to water the Avenue de rimperatrice properly^ 

 the road round the lakes^, and some few others. The whole of 

 the roads in the Bois de Boulogne, as they now stand, would 

 require ninety tons of water^ which would cost, men, horses, 

 and carts included, 13f. per ton, or 200,000f. (8000/.) for the 



