288 EXPERIMENT STATION EECORD, [Vol. 41 



Contagious epithelioma in chickens, E. Records {Nei'ndn Sta. Kid. WIS, 

 pp. 37, 38) — A study of various affected birds received has shown three dis- 

 tinct conditions t<> be encountered which presented a clinical picture hard to 

 distinguish: (1) The true contagious epithelioma due to the " scab-virus " infec- 

 tion, (2) a nonspecific type due to an infection with various microorganisms, 

 and (3) a type in which in the conjunctival sacs and suborbital sinuses, and to 

 some extent the throat, occur deposits of material distinguished from the psuedo- 

 membranes found in the other two types by their chalk-white color and being 

 extremely loose or having no attachment. A number of birds showing types 1 

 and 2 were vaccinated during the year with quite satisfactory results. The ia- 

 dications are that type 3 is of rheumatic origin. 



RTJRAL ENGINEERING. 



Machine-made cement pipe for irrigation systems and other purposes, 

 G. E. P. Smitpi (Arizona Sta. Bui. 86 (1918), pp. 71-171, pi. 1, fiys. 37).— This 

 bulletin is a general treatise on cement pipe, its manufacture, characteristics, 

 and applications. Descriptions are given of various machines used in pipe 

 making, the details of making and laying, the dangers inherent in cement pipe 

 making and in pipe lines, the testing of pipe and the results obtained, the 

 design of pipe lines and structures, and the utility of cement pipe for various 

 purposes. 



With reference to pipe it is stated that the two general classes of pipe ma- 

 chines are those employing the tamping principle and the centrifugal or packer- 

 head machines. The latter machines have greater speed and capacity per day 

 and are e.specially adapted to small sizes of pipe. The purchjise of a machine 

 and equipment requires an investment of from $4,000 to $10,000. It is stated 

 that handmade pipe is extremely variable in quality. Tamping alone does not 

 produce a smooth interior, and the pipe should be washed inside with neat 

 cement. Greater strength can be secured by inci'easing the thickness of the 

 pipe wall and by using a wet consistency of the mortar. It is stated that 

 machine-made pipe is safe when subjected to hydrostatic heads up to 25 ft., 

 and that the strength of handmade pipe of good quality is about one-half as 

 great. AVet-cast pipe can be designed to carry water under heads of some- 

 what over 100 ft. Machine-made cement pipe up to 20 in. in diameter is safe 

 In trenches under 10 ft. of back fill and the smaller sizes are safe for much 

 greater depth. Handmade pipe 16 in. in diameter, of good quality, can be 

 used under 10 ft. of earth. Machine-made pipe is practically impervious. 

 Good handmade pipe washed inside with neat cement is nearly impervious and 

 becomes entirely so in time. It is stated that in design tht; value of n in 

 Kutter's formula should be taken as 0.013. 



Cement pipe of good quality is considered in all respects the equal of vitrified 

 clay pipe for use in sewer lines. " In Arizona, where the cost of cement pipe 

 is much less than that of clay pipe, the cement pipe should be employed. 

 Cement pipe likewise should have the preference for farm and road culverts. 

 When properly made and placed, it is more durable, has a greater carrying 

 capacity, and is much cheaper than corrugated iron pipe. Cement pipe, if 

 used for draintile in alkaline areas, should be of great density and impervious." 



Composition of the waters of the inter-mountain region, J. E. Greaves 

 and C. T. Hirst (Jour. Indus, and Engin Cliem., 10 (1918), No. 12, pp. 1001- 

 100 Jf, figs. 4). — Analyses made at the Utah Experiment Station of the waters 

 of 58 Utah streams, most of which are used for irrigation, are reported and dis- 

 cussed with special reference to their suitability for this purpose. In most 

 cases samples were taken monthly during the irrigation season. 



