'Vol. XIII. Xo. 312, 



THE AGRICULTURAL NEWS. 



123 



WATER-SUPPLY. 



REPORT ON SAMPLES OF WATER 

 , FROM ELEVEN WELLS IN THE 

 VIRGIN ISLANDS. 

 Ill this itport it is stated that the samples were 

 taken by Mr. W. C. Fishlock, Curator of the Experiment 

 Station, Tortola, during the year 191-3. They represent 

 wells sunk at different points in the Virgin Islands Presidency 

 for the purpose of atl'ording local sources of water supply. 

 ■ In all eleven samples have been taken. The point of 

 origin and the analytical character of the waters are .shown 

 in the accompanying table. 



S.\.MI'LES OF WATER I'BO.M THE VIRiilN ISLAXD.S. 



No. 1. No. 2. No. 3. No. 4. No. .5. 

 Grains per gallon. 



Total solids 37-7 360 273 420 990 



Chlorine 79 85 55 75 334 



Equivalent to ) jg.Q j^.^ ,y^ ^o-^ r,-,0 

 sodium chloride / 



Temporary hard- 1 -.., -.j. ^.^ ^.j jg.p 



iiess j 



Sodium carbonate 109 70 60 103 82 



No. 6. No. 7. No. 8. No. 9. No. 10. No. 11. 

 Grains per gallon. 



Total solids 931 10-3 994 1081 833 1142 



<;hlorine 283 15-2 36 SCS 241 474 



Equivalent to l^g.g .^^.^ -g.o (jQ.g gj^.- -g.j 



sodium chloride / 

 Temporary I 



hardness 

 Sodium 



carbonate J 



none are so high as absolutely to preclude their use for 

 drinking purposes. The most saline water of all is that from 

 Anegada, which is sunk through the rock or shelf and as is 

 to be expected shows quite a high saline content relatively. 



It is an interesting feature of all these samples that 

 without exception they show the presence of small but vary- 

 ing amounts of sodium carbonate. 



In conclusion this series of wells indicates in a very 

 clear and interesting way the manner in which the local 

 needs of ditierent districts for a water supply can be easily 

 met at relatively small expense under conditions favourable 

 to well sinking. 



1 181 9-5 9-2 25-5 214 

 I-161 41 li-: 17-2 111 



7G 

 4 3 



KEY. 



N". 1 Well at Works Yard, Experiniont Station, Tortola. 



"So. 2 ., .. Curator's house. Tortola. 



>Jo. 3 ., .. 'Sundny Moinini;'. Tamarind Tree, Lower 



E.st.-\te, Tortola. " 

 No 4 Newly ilug well at Sea Cow Bay, Tortola. 

 No'. 5 Well .-It Kust End. Tortola. 

 No. li .. ,. 'Towers'. West End, Fortola. 

 No. 7 ,, ., South end of road at Valley Sottlonient, 



Virgin Gorda. 

 No. 8 ., ., north end of road. 

 No. 9 ,, ., (ireat Harbour, Josi van Dykes. 

 No. 10 .. ,, East end, Jost van Dykes. 

 No. 11 ,. ., Anegada. 



Of the total samples six are from Tortola, two from 

 Virgin Gorda, two from Jost van Dykes and one from 

 Anegada. 



"with the exception of that at Anegada, all the wells 

 are sunk in alluviil sands of the valley bottoms and derive 

 their supply fi'oni the subsoil wator .«eeping from the slopes of 

 the different catchment areas. 



In most cases the waters are well adapted for drinking 

 purposes as judged by the mineral salt content. The best 

 samples are from wells Nos. 1, 2, 3, which are associated with 

 the catchment area of the large valley to the northeast of 

 Roadtown, No. 4 from the similar valley at Sea Cow Bay on 

 the South Coast, and No. 5 from the well at the south end of 

 the road at Valley, Virgin Gorda. The samples of water 

 from other places have somewhat higher saline contents but 



A STEAM ENGINE FOR SUN POWER 



PLANTS. 



A short account of the general construction of a sun 

 power plant has aireariy been given in the AgriculturaL 

 N<:v:s. The followir^g note from the Experiin''nt Station 

 Record (December 1913) describes a new low-power 

 steam engine, which seems to work very satisfactorily 

 with the plant, particularly for purposes of irrigation 

 pumping. 



Inasmuch as the success of a sun power plant for 

 irrigation pumping and other power purposes depends largely 

 on the use of an efficient smaU power steam engine, using 

 steam practically at atmospheric pressure, the inventor 

 of this system of pumping power development produced in 

 conjunction with another engineer a low pressure, slow speed 

 reciprocating steam eng'"e adapted to the particular needs of 

 the sun power plant. The economy claimed to be obtained by 

 this engine is attributed to the combined effect of certain 

 modifications and improvements in construction, which bring 

 about a reduction of losses due to friction, valve and piston 

 leakage, and initial condensation arid clearance. 



In further developments of small power steam engines 

 these modifications were applied to a small high-pressure 

 and a small low-pressure engine having practically the .same 

 essential details. The high-pressure engine having a cylin- 

 der diameter of 1(5 inches and an 18-inch stroke was 

 tested, both condensing and non-condensing, and the 

 resulting steam consumption per brake horse power hour 

 compared very favourably with the results obtained 

 under under similar conditions from tests of several com- 

 pound condensing and non condensing engines of both 

 higher and lower power. Tests of the low-pressure engine 

 having a cylinder diameter of 36 inches and a 36-inch stroke 

 .showed a steam consumption per brake hor.se power hour 

 which compared very favourably with the results obtained 

 from tests of several higher and lower power exhaust 

 steam turbines under similar conditions. 



It is stated that the whole success of the small low- 

 pressure engine depends on the availability and maintenance 

 of a high vacuum, for which purpose specially designed air 

 and hot well pumps are employed. 



The great difference which results between the effects 

 of artificial watering of soil and watering through rainfall, 

 seems worthy of scientific investigation. The greater 

 efficiency of rainfall is no doubt due to its greater penetrat- 

 ing force, wider distribution and to the circumstance that 

 the air is at the time of the precipitation sufficiently humid 

 to arrest surface evaporation. Possibly nitric acid and dust 

 brought down in rainfall may exert some fertilizing action. 



