THE IRRIGATION AGE. 



1067 



low it goes; thus if the water stands up to line AB, the 

 hydraulic radius r equals : area of triangle ABC divided by 

 the wetted perimeter AC + BC; let AC = a, then area of 

 triangle = o~ -=- 2 ; wetted perimeter = Za, hence: 



r=^ c. 

 r = a 1 -i- 4o 



If a now is 

 doubled, r is dou- 

 bled ; if a is made 

 half, then r is 

 made r/2, the 

 general form of 

 r being a/4, a 

 being length 

 of one wetted 

 side. 



The angle 

 ACB may have a different value x; then, if h is the depth of 



x 



flow, the area of flow equals /rtg , and the wetted perimeter 



2 



2 h x 2 h 



-, hence r = li~ tg '- 



2 



which can be reduced 



.r x x 



to .5/1 tg cos = .5/i sin , which is the general form for 



22 2 



r in triangular channels. 



Fig. 77 is a rectangular section. Let CD be the 

 upper plane of flow, then area ABCD -=- (AC + AB + 

 BD) would be r. It is seen that when AC = AB the 

 hydraulic radius = AB -=- 3 ; for if AB a, area = a 2 , and 

 wetted perimeter = 3a, hence r =o 2 -=- 3a = a -=-3. 



With the width of channel constant, the hydraulic radius 

 varies with the height ; as stated above, it is o -r- 3, when 

 the cross-section of flow is a square ; r decreases with the 

 height and equals zero when the height AC is zero; r in- 

 creases as the height increases, and reaches its maximum when 

 AC equals infinity, in which case r = a -=- 2. 



The trapezoidal form of channel is shown in Fig. 78. 

 If the two sloping faces AB and CD are extended until they 

 meet in E, the section may be considered triangular with the 

 lower part BCE cut away. 



A section of this form will be useful when the variation 

 in volume of flow is not very large, and where the cutting 

 might have to be carried to too great depths if the true 

 triangular form were adopted. 



Best conditions are obtained if angle AED = 90 and angle 

 AEF = 45 '. This would make the slope 1 to 1, which might 

 have to be modified for the various conditions under which 

 the channel is to be constructed. 



Assume angle AEC = 9Q and BC = a; let GH be flow 

 line and /t = depth of flow; then area of flow: (a-\-h)h; the 

 wetted perimeter P = GB + BC + CH; GB=^HC V^ 2 = 

 hence wetted perimeter /> = a -4- 



If we divide f into area we get r = 



r = h (a -{- h) -H (a -f- 2h V~2)- 



It is seen from this formula that r increases as h and a 

 are increased; if a is made equal to zero the formula changes* 



R = h 2 -H 2/1 V2~= h -r- 2 v' 2T~ 



This is the case of the triangular section expressed in 

 terms of the depth of flow. When It and a are equal the 

 formula of r appears thus : 



r = h(h + h) +- h +_2/i( \/2~ 



r = 2h 2 -h(l + 2\/Z), which may be simplified to: 



r = 2/1 -r- 1 + 2 \/2~ 



r = /!-=- 1.914 = .52/1. 



This is equal to more than half of the height and is the 

 best section for high velocity of this kind. 



If the angle AED = x, then the flow area will equal 



2 ' h 



A MOVE IN THE RIGHT DIRECTION. 



If apple growing can be put on a sure and profitable 

 basis in Iowa, the horticulture and soil experimentalists 

 of the experiment station at Iowa State College have de- 

 termined to find out how. 



To this end, the director of the station, C. F. Curtiss, 

 has leased an established orchard of twenty-three acres 

 in Pottawattamie county, near Council Bluffs, for a period 

 of ten years. Here Prof. S. A. Beach of the horticulture 

 section and Prof. W. H. Stevenson of the soils section 

 and their assistants will apply the best known methods of 

 cultivation so that Iowa orchardists may be practically 

 advised how to put their orchards on a paying basis. 

 Laurenze Greene, station experimentalist, will have imme- 

 diate charge of the project. 



The orchard will be put into proper condition by 

 pruning and otherwise as soon as possible. The ground 

 will be divided into different plots and given different 

 methods of cultivation. In the spring, an organized fight 

 against frost will be made with the best oil-heater appara- 

 tus. In the spraying season the trees will be thoroughly 

 treated for apple pests. In the fall the fruit will be har- 

 vested and marketed in a business-like way. 



The study of the soils of the orchard and their re- 

 sponse to different treatments promises to be one of the 

 most valuable features of the experiment. Very few 

 orchardists in Iowa realize the importance of maintaining 

 the fertility of orchard soil. They rob it year after year 

 without putting anything back into it and then wonder 

 why apples are not successfully grown. For this experi- 

 ment the orchard has been divided into six plots, running 

 across the rows of trees, which include a dozen varieties, 

 so that every plot contains all the varieties. Plot Xo. 1 is 

 seeded to clover, which will be cut and allowed to remain 

 on the ground as a mulch; every second year the lot will 

 be plowed and reseeded to clover. Plot 2 will be thor- 

 oughly cultivated each year until midsummer and then 

 seeded to some leguminous cover crop which will be al- 

 lowed to grow and then be plowed under in the spring. 

 Plot 3 will be given clean cultivation throughout the sum- 

 mer. The fourth plot is seeded to blue grass, which will 

 be cut and allowed to remain on the ground as a mulch; 

 this plot will not be plowed, however. The fifth and sixth 

 plots will be treated as the first and second. 



The effect of these methods on the humus, moisture 

 and plant food content of the soil will be carefully deter- 

 mined, and also the effect on the trees in their growth 

 and fruit bearing. 



Books upon every phase of the experiment will be 

 kept carefully so that as the experiment progresses it 

 may be pretty definitely gathered from results whether 

 scientific orcharding can be made to pay in Iowa as well 

 as in other sections of the country. The records will 

 show also what methods are most satisfactory. The 

 orchard chosen for the experiment is a fairly representa- 

 tive orchard and what may be done with it may be done 

 with most Iowa orchards. 



Those in charge of the experiment have faith in Iowa's 

 ability to produce apples successfully. They hope to prove 

 their faith and show how orchards may be made to pay. 



h(a + /i tg ) and the wetted perimeter = a -I- x, hence 



2 cos g" 



/z (a + * tg .r 



2_ 



a + 2 h__ which is the general form for the trape- 



x 



cos ^ 



zoidal channel. 



ASPINWALL MANUFACTURING COMPANY'S AN- 

 NUAL MEETING. 



The annual meeting of the stockholders of the Aspin- 

 wall Manufacturing Company was held at the company's 

 offices in Jackson, Michigan, Tuesday, August 8, election 

 of board of directors being held. The directors in a sub- 

 sequent meeting elected the following officers for the en- 

 suing year: President, L. A. Aspinwall; vice-president 

 and manager, C. G. Rowley; treasurer, G. N. Whitney; 

 secretary, J. A. Parkinson, Jr. The company has enjoyed 

 a successful year in all respects and prospects for 1912 are 

 exceedingly bright. 



Engineer J. W. Mavity of Lyndon, Kansas, has just 

 returned from Texas, where he has been making surveys, 

 plans and specifications for an irrigation project on the 

 Pecos River, Pecos County, Texas. 



