RURAL ENGINEERING. 507 



pp. 384, pis. 2, fig. l |; pt. II. The Greal Basin and Pacific Ocean drainage in Cali- 

 fornia. W. B. Clapp (No. 134, pp. 276, pis. 2, fig. 1); pt. 12, Columbia River and 

 Pugel Sound drainage, D. W. Ross, J. T. Whistler, and T. A. Noble (No. L35, pp. 

 300, pis. 2, fig. I i. 



Movable dam and lock of the Rice Irrigation and Improvement Associa- 

 tion, Mermentau River, La. i Engin. News, 54 I 1905), No. IS, pp. 321, 822, fig 

 \ history and description of a dam used for shutting out the Bail water of the Gulf 

 of Mexico during the period when the irrigation pumping plants take more water 

 from the river than is furnished by its natural flow, thus lowering the level of the 

 water in the river below the Gulf level. 



Compound centrifugal pumps, \V. Frecheville {Engin. and Win. Jour., 80 

 . No. 18, p. 832). This article deals chiefly with an accounl of a planl for lift- 

 ing 1,000 gals, per minute from a depth of 1. 150 ft. in a mine in Spain. Four quadruple 

 centrifugal pumps in series are driven by three phase motors. The pumps have 

 worn well and are guaranteed to have an efficiency of 68 per cent. The surface 

 steam plant and pumps have a combined efficiency of about 50 per cent, producing a 

 water-horsepower hour on 4.8 lbs. coal. 



The value of windmills in India, A. Chatterton I Madras, 1903, pp. 8-15, dgm*. 

 §). — An experimental equipmenl was erected at Madras consisting of a 16-ft. wind- 

 Boil] of American manufacture on a 70-ft. tower, attached to an 8-in. pump with a 

 stroke of 16 in., and connected to suitable measuring tanks. 



The 70-ft. tower raised the mill "well above the influence of obstruction to the 

 wind caused by buildings and trees, and the whole country for miles around is a 

 practically dead level plain." The mill was geared hack \\\ to 1. Many careful 

 measurements showed the discharge of the pump to be 86 per cenl of the theoretical 

 lischarge. A tachometer was attached to the windmill for counting it- strokes and 



\\:i- read three times daily. The lift of the pump was maintained at exactly 25 ft. 

 The mill and pump were in continuous operation for more than a year. Hourly 

 Readings of the wind movenient were obtained from the observatory about a mile 

 distant from the mill. 



From a comparison of all the observations it was found that they were verysatis- 

 ■ctorily represented by the following equation: X=210 (y 53), in which "x" is 

 the number of United states legal gallons lifted 25 ft. per twenty-four-hour day; 

 and "y" is the total daily wind movement in miles. 



"( lareful observations on Beveral days with an anemometer tixe.l to the w indmill 

 tower showed that it required a steady breeze of about 7.5 miles per hour to keep the 

 windmill in continuous motion, hnt that, when the wind velocity exceeded •'! miles 

 per hour, a certain amount of work was done as the result of puffs of w ind." 



Selecting a considerable number of intervals during which the w ind blew with an 



almost constant hourly velocity greater than 8 miles per hour, it was found that these 

 ■Bsults were represented with great accuracy by the equation \ = 188 y, in which 

 the letters represent the same quantities as before. This equation i- based upon the 

 results of some twenty-three different four-hour periods, the minimum wind velocity 

 being 8 and the maximum about 15 miles per hour. 



"When the daily wind velocity is below 53 miles per day, the amount of work 

 ■one by the windmill is negligible, bul above that velocity it steadily increased in 



direct proportion to the increased rate of the movement of the wind. This result is 



one of extreme importance, because makers of windmills invariably claim that the 

 work done by a windmill i«^ proportional to the cube of the wind velocity; and in 

 their catalogues and price lists they publish fictitious tables showing the work done 

 by the wind at various velocities." 



After a discussion of the monthly wind movement, rainfall, and irrigation require- 

 ments, the author reaches the conclusion that a 16-ft. mill "will do sufficient work 



