688 EXPEEIMENT STATION RECORD. 



specimens were coustautly exposed either to water or dry air, markedly reduced 

 the shrinliage due to the draining off of the surplus gaging water and also the 

 extent of the movement when the test piece was ultimately wet and dried. 



Portland cement mortars and concrete either with or without the addition 

 of hydrated lime developed the greatest strength when in continuous contact 

 with water, and when allowed to harden in air without water there was a 

 marked diminution of strength. Considered broadly, the addition or substitu- 

 tion of 10 per cent of hydrated lime had no marked effect on the strength of 

 the mortars. 



It is concluded that the addition of hydrated lime will be found advantageous 

 under ordinary climatic conditions, not only in concrete road construction but 

 in concrete work generally. 



Power from the sun, F. Shuman (Engin. Mag., Jft (191^), No. 3, pp. 419- 

 Jf23, fig. 1). — A description is given of the main features of construction and 

 operation of the sun-power plant for irrigation pumping at Cairo, Egj-pt. 



The engine used is a special low-pressure engine previously described (B. S. 

 R., 29, p. 787). The steam is generated in the sun heat absorbers which are 

 jipproximate parabolic troughs for catching the sun's rays and concentrating 

 them upon the boiler swung at the focal point. Tests of the steam-producing 

 capacity of the heater showed the average production to be 1,100 lbs. per hour 

 of 15 lbs. steam (absolute pressure) for a 10-hour day, giving on an average 50 

 brake horsepowei". A comparison of the cost of erection in that locality of this 

 plant with that of a coal-burning plant of equal horsepower showed a total saving 

 in cost of erection and operation in favor of the sun-power plant of £410 6s. 

 (about $2,000). The plant is said to have a thermal efficiency of 57 per cent. 



Gas-engine indicator diagrams, G. W. Muench (Power, 39 (1914), No. 22, 

 p. 775, figs. 8). — Seven actual indicator diagrams taken on gas engines are given 

 and comitared with a normal diagram from a four-stroke cycle engine, thus 

 showing how some of the common gas-engine troubles, such as improper timing 

 of valves and Ignition, preignition, faulty compression, excessive back pressure, 

 etc.. may be detected by the indicator diagram. 



Strength of shafting required to transmit a given horsepower at different 

 speeds, C. H. Clark (Sci. Amer. Sup., 77 (1914), No. 2003, p. 331, fig. 1).— 

 Formulas and a diagram are given for computing the size and strength of 

 shafting required to transmit a given hor.sepower at different speeds. 



Transmission of power by Manila rope, R. Tbautschold (Power, 39 (1914) > 

 No. 19. pp. 666-670, fig.f. .9).— Charts and formulas for figuring the power trans- 

 mitted by rope drive, the sizes of sheaves, etc., are given, and the character- 

 istics and advantages of rope drive are discussed. 



The implements of the industry, H. P. Agee (Hawaiian Sugar Planters' Sta., 

 Agr. and (Jlicm. Bui. 44 (lUl.'t), pp. ,S.}, figs. 7^).— This is a compilation of in- 

 formation regarding a number of the methods and implements used in the culti- 

 vation of sugar cane in Hawaii. 



Permanent farm buildings, J. B. Davidson (Brick and Clay Rec, 44 (1914), 

 No. 10, pp. 1140-1143. figs. 9).— The author draws attention to the economic 

 importance of permanent construction of farm buildings, points out in a general 

 way the requirements for such construction, and advocates particularly the use 

 of clay products as building material. 



Transmission of heat through building materials, F. L. Busey (Power, 

 39 (1914), No. 16, pp. 572-574, fid- i)-— In the interests of both building heating 

 and refrigeration the author analyzes mathematical methods and gives tables 

 of data for computing the heat transmission and the transmission resistance of 

 different building materials. 



