TuE Bulletin. 17 



sufficiently. On first installincj our heating system we used %-ineh 

 pet-cocks for exluuists, but soon found them to be constantly plugging 

 up with scale and other foreign substances. After replacing them 

 with l/^-inch globe valves there was no trouble. The globe valves can 

 be readily opened and all scale and condensation water blown out 

 occasionally. Half-inch globe valves were found to answer as well 

 for exhausts as the inch size, so reducers were put in and considerable 

 saving in cost etl'ected on the whole system. In lettuce heating, as 

 in all long stretches of pipe, expansion joints have to be put in at 

 intervals to allow for expansion and contraction. 



In wide frames the heating-pipe is run down the centre of the 

 bed and stapled to the centre posts sustaining the ribs for the cover. 

 For heating purposes the narrow beds seem to give best results. The 

 lettuce at the rear or high portion of the frame matures first, so the 

 pipe is placed 3 feet from the lower edge of the frame. This 

 equalizes the heat throughout the frame, as the heat rises to the 

 cover and passes up to the higher portion at the rear of the bed. 

 In wide frames there does not seem to be as good a circulation or 

 distribution of heat. Wide frames have proven to be best for raising 

 lettuce without heat. 



IRRIGATING. 



In winter lettuce-growing in eastern North Carolina irrigation is 

 not a necessity, but with high-value crops and intensive cultivation 

 it does not pay to wait for nature's showers. To keep such crops 

 growing rapidly for the higher prices of the early market it pays to 

 have facilities for supplementing the natural rainfall. In the arid 

 reeions of the West, where lack of rain is constant and continuous 

 during the growing season, necessarily expensive systems must be 

 installed. Under our eastern conditions irrigation is only supple- 

 mental and consequently must not be too expensive. In lettuce-grow- 

 ing the irrigating system may be combined with the heating system 

 and its cost thereby reduced. The boiler that provides the steam 

 for heating can also furnish steam for pumping. 



Where water can be obtained from artesian wells, open furrow 

 irrigation is the simplest and cheapest method. It is only in excep- 

 tional localities that such natural facilities are obtainable. In most 

 localities irrigation water must be applied through pipes. The 

 simplest and cheapest irrigation system is that which uses the heat- 

 ing-pipes for supplying the water. At intervals of about 20 feet 

 along the heating-pipes, upright pipes, 4 feet in length, are attached. 

 From the ends of these uprights the water is distributed by rose noz- 

 zles. This system, though simple and comparatively inexpensive, has 

 not given as good results as where the water is applied as a spray 

 from separate overhead pipes. This latter is kno^^Ti as the Skinner 

 method, and is now most commonly in use by lettuce-gi-owers. Large 

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