RURAL ENGINEERING. 189 



pis. 5). — This companion work i.s ari-anged on the plan of the guide previously 

 noted (E. S. R., 33, p. 87). 



The control of contagious epithelioma in chickens by vaccination, W. B. 

 Mack and E. Records {Nevada Sta. Bui. 82 (.1915), pp. 5-16). — This is a report 

 upon vaccination experiments made during the course of outbreaks in seven 

 flocks, brief reference to which work has been previously noted (E. S. R., 33, 

 p. 676). 



" The use of a virus prepared by triturating the morbid products collected from 

 the skin and mucous surfaces and attenuated at 55° C. for one hour checked the 

 spread of the disease promptly and exercised a favorable influence upon visibly 

 infected birds. Cases thus treated ran a shorter and milder course than those 

 not treated, and the mortality was materially reduced. Two injections were 

 suflicient in most instances, but severe advanced cases benefited by a third and 

 larger dose." In five flocks, containing 3,062 birds, 1,668 of them thoroughly 

 exposed and 1,394 visibly infected, the spread of the disease after vaccination 

 was negligible. Of the 1,394 visibly infected birds treated, 1,094, or 78.55 per 

 cent, recovered. 



" On the whole the treatment was satisfactory and successful. In five flocks 

 no unfavorable results followed the subcutaneous administration of the vaccine, 

 but in two flocks serious toxic and septic processes were apparently caused by it. 

 The crude preparation used is not, therefore, without danger, and a more refined 

 product must be devised." 



Campaign to eliminate bacillary white diarrhea (Massachusetts Sta. Circ. 

 56 (1915), folio). — The agglutination test for the detection of the causative 

 organism of this disease (Bacterium pnllorum) having made it possible to elimi- 

 nate infected fowls from breeding flocks, the station cooperating with the exten- 

 sion service herewith announces its preparedness to begin testing breetling hens. 

 The collection of blood samples will be made by the extension service, and the 

 agglutination tests by the station. 



RURAL ENGINEERING. 



Excavating machinery used in land drainage, D. L. Yaenell (U. S. Dept. 

 Agr. Bui. 300 (1915), pp. 37, pis. 9, figs. ^).— This bulletin discusses the de- 

 velopment of excavating machinery and deals with the essential features of con- 

 struction, cost, operation, cost of operation, and selection for certain conditions 

 of the floating dipper dredge, the floating grab-bucket dredge, the dragline 

 scraper excavator, the dry-land dipper excavator, the dry-land grab-bucket ex- 

 cavator, the templet excavator, the wheel type of excavator, the hydraulic 

 dredge, and machines for cleaning old ditches. 



" The floating dipper dredge is more widely used in drainage work than is any 

 other type of excavating machine. For work through wet land no other ex- 

 cavator will equal it in cheapness of construction of ditches having a cross sec- 

 tion of from 100 to 1,200 sq. ft. It is by far the most efficient machine to use 

 where many stumps will be encountered. Owing to its limited reach it is not 

 generally applicable to levee construction. . . . The floating dipper dredge 

 should be operated downstream, where practicable. 



" In general, the clam-shell or orange-peel dredge is not well adapted to ditch 

 construction, especially if there are stumps to handle. Certain types of soil, 

 such as the muck of southern Louisiana, can, however, be handled to advantage 

 with this machine. It is also suited to levee building when equipped with a long 

 boom. 



