1920] EURAL ENGINEERING. 587 



than beins of only secondary imixtrtance as assumed by Salmon.* Such 

 conclusion is based upon the fact tluit "100 per cent infection was obtained 

 in all chicks fed earthworms taken direct from the original infected soil. 

 No chick contracted gapes from gape-infected chicks of the same age even 

 when closely contined with them. Neitlier of the two chicks fed gape worms 

 taken from chicks which died from the disease became infected. None of the 

 24 chicks allowed to partake freely of earth direct from the infected yard 

 contracted the disease. While Megnin,' Walker, Salmon, Kan.som,' and others 

 showed it possible to produce gapes in clucks by feeding them gape worm 

 eml)ryos hatched in water, ft seems improbable that under practical condi- 

 tions such contaminated water would be available to the chicks except in rare 

 instances. It is shown conclusively that earthwo4-ms are capable of playing 

 an important part in carrying gapes over from one season to another. Adult 

 fowls were infected with gapes by feeding them earthworms from the infected 

 chick run. It is pointed out that the important method of treatment is to pre- 

 vent the disease by keeping the young chicks from obtaining infected earth- 

 worms. This can usually be done by growing the chicks on new land or con- 

 fining them when the ground is wet with rain or dew, at which time earth- 

 worms are at the surface." 



The chicken sticktight flea (Sarcopsylla gallinacea Westw. ), C. E. San- 

 porn {Oklahoma Sta. Bui. 130 {1020), pp. 3-8, figs. 4). — This is a popular sum- 

 mary of information. The author recommends the use of a 5 to 10 per cent 

 mixture of kreso in vaseline or lard ; or a mixture of carbolic acid, 1 part and 

 vaseline 5 parts ; or 1 part of kerosene to 2 parts of lard, applied to the infested 

 parts. Four parts of zenolium in 100 parts of water, sprayed in the poultry 

 houses and yards, is said to be quite effective. 



I RURAL ENGINEERING. 



Agricultural associations for irrigation of soil according to Italian prac- 

 tice, E. F. Caselli {But. Inst. Egypte, 1 {1919), pp. 71-85).— The legal and 

 economic phases of irrigation practice in Italy are discussed, with particular 

 reference to the organization and operation of irrigation associations or districts. 



Precast concrete slabs for small irrigation structures, R. W. Olmsted 

 (Engin. News-Rec, SJ, {1920), No. 2.',, pp. 1167, 1168, figs. 5).— Precast concrete 

 slabs for small irrigation structures are described, and experience on their use 

 on several California irrigation projects is discussed. They are used especially 

 for gates, checks, and drops, and no nails or bolts are used in assembly. The 

 bond between slabs is obtained by beveled lugs on the ends and sides, which 

 fit into corresponding recesses in the adjoining slabs. Beams are used as 

 spreaders. The structures are designed so that joints between slabs will 

 come where the bending moment is least, thus requiring the lugs to resist 

 shear only. 



The reinforcing consists of 6 by 6 In. galvanized No. 6 wire mesh. At 

 current prices the cost is about the same as it would be for redwood lumber, 

 and it is stated that the saving in cost of the precast gate over the cost of 

 monolithic structures varies from 2.5 to 40 per cent. The amount of concrete 

 per slab gate is only from one-third to one-half of the monolithic structure. 



Factors afl'ecting the use of water in irrigation, E. A. Moritz {Engin. 

 News-Rec, 84 {1920), No. 24, pp. 1150-1155). — This paper, a contribution from 



1 Rcpt. U. S. Dept. Agr., 1885, pp. 274-277. 

 >Rept. U. S. Dept. Agr.. 1884, pp. 281-206. 

 •Ann. Kept. Sec, U. S. Dept. Agr., 1917, p. 122. 



9846°— 20 7 



