284 MOTIVE POWER EMPLOYED

hour, then the energy of their power, in travel-ling the same distance, is diminished one half,as shewn in the Table, where 100 cwt. is theload with which they can travel at the rate offour miles an hour. We see, therefore, thatthe value of loco-motive engines dependsolely on the speed which they accom-plish in travelling ; and this, as beforeseen, will be regulated by the length ofstage, and the nature of the road on whichthey are applied. The most extravagant ideasare at present entertained of their value, andthe velocity with which they may be made totravel; something of this took place also attheir first introduction, and they were henceemployed upon Rail-roads, the most improperfor their action ; and it is not on that accountwonderful that they should, in some instances,disappoint the expectations of their sanguinesupporters. I have given experiments to shew,that they urc capable, in their present shape,with 4-feet wheels, of accomplishing a rate ofsix miles an hour. It need scarcely be urged,that, if they can travel at that velocity, theycan also be made to travel at a less rate ofspeed ; the cost will perhaps be less ; smallerengines might be employed, and the consump-tion of fuel will be diminished: still their