IRRIGATION" IN FLORIDA. 53 



point where the iron main from the pump connected with the low- 

 pressure distributing system. This relief stand consisted of a con- 

 crete box about 4 feet square and 12 feet high, open at the top. The 

 iron mains entered near the bottom on one side and two terra-cotta 

 pipe lines led out near the bottom of the stand. Each of the terra- 

 cotta outlets was fitted with a sliding gate which could be opened or 

 closed by means of a long handle from the top of the relief stand. 

 The top of this relief stand, or standpipe, was 3 feet above the highest 

 elevation of the grove. If every valve in the terra-cotta lines was 

 closed the water would rise and overflow the standpipe without ex- 

 erting excessive pressure on the distribution system. 



Water was distributed over the grove by diverting it into furrows, 

 three or four furrows being placed between each two tree rows 

 (PL V, fig. 2). In order to facilitate the distribution, outlet valves 

 were placed in every tree row, and seven or eight of these were 

 sometimes left open at the same time, thus permitting 24 to 28 fur- 

 rows to be supplied with water simultaneously. Water ran 400 to 

 500 feet in the furrows, and only one man was needed to operate the 

 system. The furrows were made with an ordinary sweep shovel 

 plow. 



The outlet valves installed first were similar to those used exten- 

 sively in southern California for orchard irrigation, and allowed 

 the water to escape in four or five small streams from a central 

 stand. Trouble was experienced with these in keeping the water 

 divided into the furrows in sandy soils; hence the above-mentioned 

 local type, which did the work much better, was devised. 



The improved valve, as designed for the experiment, is being used 

 now for special Florida conditions on low-pressure pipe systems. It 

 is made of cast iron and brass and is expected to stand low heads 

 only. Its operation is very much like that of the ordinary hydrant 

 and it may be regulated to discharge various amounts of water. 

 The ordinary 6-inch size is made with either one or two outlets. 

 The two-opening valve is used when furrow irrigation is practiced, 

 while the one-opening valve is used in connection with portable slip- 

 joint pipe. One-opening valves can be connected to two-opening, 

 or vice versa, at any time by substituting a change of body. Ordi- 

 nary 6-inch gate valves could be used, but the expense would be 

 prohibitive, probably averaging four to six times as much as that 

 of the low-pressure valves. The low-pressure valve of the above 

 type is provided with a bell end, similar to the bell end of a terra- 

 cotta pipe section, for cementing to the 6-inch riser in the same 

 manner that one length of terra-cotta pipe is cemented to another. 



Experiments made in distributing water in the grove near Orlando 

 by means of these valves were very satisfactory. Short lengths of 



