RURAL ENGINEERING. 883 



these experiments .mikI of the ineohanism and operation of gas engines in gen- 

 eral with a sliort treat iiicnt ot" the comparative cost and relative adaptability of 

 different fncls. 'I'lic principal conclusions derived from the experiments are 

 as follows : 



"Any en^'iiic mi llic Aiiicrican market to-ihiy, ojierating with gasoline or 

 kerosene, can (>i)crate witli alcoiiol fuel without any structural change whatever 

 with projjor manipulation. 



"Alcohol contains approximately ().(j of the heating value of gasoline, by 

 weight, and in the Department's experiments a small engine required 1.8 times 

 as nuich alcohol as gasoline i)er horsepow(M' hour. This corresponds very 

 closely with the relative heating value of the fuels, indicating principally the 

 same tlicrmal efficiency with the two when vaporization is complete. . . . 



" The thermal efhciency of these engines can be improved when tliey are to 

 he operated by alcohol, first, by altering the construction of the carbureter to 

 accomplish complete vaporization and, second, by increasing the compression 

 very materially. . . . 



"The exhaust from the alcohol engine is less likely to be offensive than the 

 exhaust froni a gasoline or kerosene engine, although there will be some odor, 

 due to lubricating oil and imperfect combustion, if the engine is not skillfull.v 

 operated. 



" It requires no more skill to ojierate an alcohol engine than one intended for 

 gasoline or kerosene. 



" There seems to be no tendency for the interior of an alcohol engine to 

 become sooty, as is the case with gasoline and kerosene. . . . 



" In most localities it is unlikely that alcohol power will be cheaper or as 

 cheap as gasoline power for some time to come." 



Windmill electric plant requirements (Etigin. Rec, 55 {1901), Mo. 2, p. 

 Jf7). — The essentials in installing a windmill electric plant have been stated by 

 W. O. Horsuaill, of England, as follows: 



First, to ascertain the average daily load in ampere-hours during periods of 

 maxinuun ciu'rent consumption ; second, to provide a storage battery of a 

 capacity at least double this output; third, to install a dynamo of sufticient 

 capacity to charge this. battery in 12 hours; fourth, to design a dynamo to 

 delivei- an ai»i)roximately constant voltage throughout a wide range of variation 

 of .speed; fifth, to erect a windmill of ample size to run the dynamo at full load 

 with u 10-mile-an-hour wind; and sixth, to fit the windmill dynamo and all 

 gearing connections with roller-bearings or other friction-reducing means. A 

 large number of plants built to these .specifications are said to be in successfxil 

 operation in Kngl.md. 



The production and utilization of low temperatures, L. Marciiis {Produc- 

 tion ct I tilisaiioii (111 Froid. I'uiis: H. Dunod and E. Puiat, 190(i, pp. IV-\- 

 5HG. fli/s. .'i().i). — This work is intended to supply a want long felt in France 

 for a general text on the subject of refrigeration. 



The introduction takes up the subject of the development of the refrigerating 

 industry showing the manifold uses to which ii «> is at present put and giving 

 statistics on the extent to which refrigeration is carried on not only in the 

 pjicking and allicnl industries but also in transportation by laud and water 

 in the various countries. Following this several chapters are devoted to the 

 thermo-dynaniic theory of refrigeration and to descriptions of the principles 

 underlying the action of different machines and their design, pai'ticular atten- 

 tion being given to the machines of the compression type. Different forms of 

 condensers and evaporators are described and illustrated and the circulating 

 medium discussed. 



Some special applications of the use of refrigeration in dairies and i)reweries 



