784 EXPERIMENT STATION RECORD. 



4. In testing the fuel consumption the fact was kept in mind that it is 

 important to Icnow not only the amount consumed during the run, but also the 

 amount consumed during the night when the fire was banked. It was concluded 

 that where coke could be obtained it would be a more desirable fuel than anthra- 

 cite coal, even when not considering the greater tendency of the latter to produce 

 tar. In the 11 plants tested the consumption per brake horsepower at full load 

 varied between 1.04 and 1.48 lbs. ; at half load between 1.38 and 1.98 lbs. ; and 

 at i'ull load with coke between 1.21 and 1.G5 lbs., while the difference between 

 the best and the worst plants at full load was less than i 11). of coal. The differ- 

 ence among the better plants was almost insignificant, amounting to no more- 

 than 0.04 lb. Questions of economy can, therefore, be left out of account in 

 deciding upon the make of plant to use, the decisive factor being cost per brake 

 horsepower. This varied in the tests given between .$44 and .^8.5, the winners 

 of the awards both pricing their plants at about .$50 per brake horsepower. 



An interesting fact developed at the trials was that as much water was 

 required for the operation of these plants as would be necessary for a steam 

 engine plant. Various tables are presented, giving details of the test, such as 

 compression, explosion, and suction pressures, and other data, making the report 

 one of unusual interest and value. 



Additional information on the durability of wooden stave pipe, A. I^. 

 Adams (Eiujin. News. 56 {1906), No. l'>. p. J7.S, fu/. 1). — A wooden stave pipe 

 at Astoria, which is buried in the earth and is under constant water pressure, 

 has proven deficient in durability, contrary to preconceived ideas as to the 

 behavior of wood under such conditions. The pii)e in question deteriorated so 

 much in ten years that extensive renewals and repairs became necessary during 

 1905. The facts made prominent from the experience with this pipe are as 

 follows : 



" <1) Staves, which are constantly subject to water pressure from within and 

 are buried in the ground, may be very short-lived. 



" (2) The magnitude of the w^ater pressure, beyond a moderate head, has had 

 little or no influence in preserving the timber. 



" (.3) The pipe laid above ground has not deteriorated to any considerable 

 extent, nor has the pipe laid in the tunnels leading from the distributing 

 reservoir. 



" (5) \Yhen the depth of backfill has exceeded 2 ft. above the pipe, and the 

 material has been free from vegetable matter, and has been of a fine and imper- 

 vious character, nmch less deterioration has taken place. 



" (T) Decayed staves have been found all around the pipe. 



" (8) Sound staves have been frequently found contiguous to badly decayed 

 staves. 



" (10) The bruising of the staves during the process of erection seems to 

 have been one of the chief agencies in hastening decay. 



" (11) Decay has been confined to the outside of the pipe. 



" (13) The malleable cast band fastenings have been found to be in good con- 

 dition." 



Economics of road construction, II. P. Gillette (New York: The Engineer- 

 ing News Fuh. Co.. 1906, 2. ed.. pp. Ji9, figs. 9). — In this work the author under- 

 takes to point out certain defects in current road engineering practice and to 

 correct certain common erroi-s in estimates and specifications. He advises 

 designing the cross section of the road in such a way that modern excavating 

 and grading tools can be used in construction. It is claimed that deep side 

 ditches are unnecessary, since the heaving action of frost is said not to affect 

 materially a macadam road with a foot of dry soil beneath it. In view of the 



