ON DRAUGHT. 531 



' The annual expense of a higli-pressui'e locomotive engine, or steam 

 carriage, consists of: — 



' 1. The interest of the first cost. 



' 2. Decrease of value. 



' 3. Hazard of accidents. 



' 4. Value of coals and Avater. 



' 5. Renewals and repairs. 



' 6. Expense of attendance. 



' It is difficult to procure these particulars from the experience of those 

 who employ engines ; we will therefore annex, by way of example, such 

 sums as we think likely to cover the expense. The first cost of the engin(! 

 and its carriage may be stated at 501. per horse-power, and its decrease of 

 value and hazard will render its annual expense about one-fifth of its first 

 cost, or 101. per annum per horse-power. The expense of fuel and water 

 per day will be not less than one bushel and a half of coals per horse-power 

 and fourteen cubic feet of water ; and, taking the coals at 6d. per bushel, 

 and the water and loading with fuel at Sd., the annual expense will be 

 15Z. 12s. ; the renewals and rejiairs, at 20 per cent, on the first cost will 

 be 101., which is as little as can be expected to cover them. Attendance, 

 suppose one man and one boy for each six-horse engine, at 6s. per day, or 

 Is. per day for each horse-power, or 151. 12s. per annum ; therefore the 

 total annual expense of one horse-power would be 511. 4s., or 158 farthings 

 per day.' — ^This power is equal to a force of traction of 166§ lbs. for the 

 same number of miles per day as the horse ; but from this gross amount ol 

 power we must deduct that necessary to move the engine with its supply 

 of coals : this will reduce it at least to 155 lbs. ; consequently, in the one 

 case we have a force of traction of 125 lbs., at an expense of 186 farthings, 

 and, in the other, a force of 155 lbs., at an expense of 158 farthings ; and 

 reduciug them both to one standard quantity of work done, we find the 

 expense of the horse is -J|^=1.488, and of the locomotive engine, 1.019, ot 

 about as 147 is to 100. In this case, therefore, there appears to be a de- 

 cided economy in the use of the steam-engine, and accordingly its applica^ 

 tion has become very general, and is becoming more so every day. 



Let us now examine what alterations are requisite before we can applj? 

 these calculations to the case of draught upon common roads ; supposing 

 both species of power equally convenient and applicable, and confining oui 

 observations merely to the amoiint of power and proportionate expense. 



The force of traction of the horse, and the yearly cost, will remain so 

 nearly the same, that for our present purpose we may consider them quite 

 unaltered. Not exactly so with the locomotive eng-ine. 



All the parts of the machine must be made much stronger and heavier, 

 and consequently more expensive for road-work than for a railway, and, 

 therefore, the first cost will be greater — the wear and tear wiU also be 

 greater, and as the work will be more variable, the consumption of fuel 

 will be increased as well as the price, which, generally speaking, will be 

 much less on a line of railway than it can possilaly be elsewhere. 



Still all these circiimstances will not influence the result so much as the 

 increased efiect of the weight of the engine. On a railway with the car- 

 riage, as now constructed, the force of traction is not much more than -^^ or 

 2-J-Q of the weight moved ; consequently, the power necessary to move the 

 engine itself is not very considerable. On a road, however, this proportion 

 is materially altered ; here the average force requii'ed to move a well-con- 

 structed carriage cannot be estimated in practice at less, even when the 

 roads are in good repair, than ^rV ; the engine, according to the construction 

 of the best locomotive engines now in use, will weigh, with its carriage 

 and fuel, at least one-half ton, or 1120 lbs. per horse-powe:*, and^s'^ of 1120 



M jr 2 



