Page:Indian Journal of Economics Volume 2.djvu/40

 S2'NLEY JEVONS faster method. Consequenfiy hese examples serve to show he exten of he increased cpial outJy which m 3 under ordinary circumstances be remunerative by. reducing loss of interest. Under oher circumstances he figures my vary indefinitely, nd ech cse will require separate calculation principles here se forth. in accordance wih he In addition to unnels and bridges, and other essen- psrs of railways, we may noe he following ss s few more examples of he kinds of eases in which his principle needs to be kep in mind. In an irrigation canal system he building of he weir $ he head works migh tke much longer hsn he con- struction of he canal iself and is distributaries, sud increased expenditure 'to accelerate is completion might be justified. Again, s coal-mine csnno begin raising eosl until s second shaf for ventilation and emergency exi ptrposes is completed; and $ more cosfly method of sinking which saves time may prove highly remuners- five. Suppose, again, hs $ new large factory hs been entirely equipped, bu hs s vit, sl psr of he engine is found to be broken or de[eefive, i will sve money to obtain his in India, paying, if necessary, tmu or. wenty times he price which i would be necessary to pay to obtain i from Europe in he ordinary course sfber s lapse of 'wo or hree months. The general principles desl wih in his section are sriefiy of s mathematical character, and he differentb cases could be calculated from suitable formnlra if 11 he dst were given. I wold be outside he scope of my presen purpose, however, 'to go minutely into the subjec here; and i will sulce if I give he following rule which may be useful to guide engineers and 8dministrsfive olcers engaged with large projects :-- /u/:--The value of additional speed n construe. tion--ths is to say, the rsfio of percentage inemsse