522 ON DRAUGHT. 



" 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 engine and its 

 carnage may be stated at 50/. per horse power, and its decrease of value and 

 hazard will render its annual expense about one-fifth of its first cost, or 10/. 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 3d., the annual expense will be 15/. 12.9. ; the renewals and repairs, 

 at 20 per cent, on the first cost, will be 10/., which is as little as can be expected 

 to cover them. Attendance, suppose one man and one boy for each six-horse 

 engine, at 6.?. per day, or Is. per day for each horse-power, or 15/. 12-s. per 

 annum; therefore the total annual expense of one horse-power would be 

 51/. 4*., or 158 farthings per day." This power is equal to a force of traction 

 of 16G|-lbs. for the same number of miles per day as the horse ; but from this 

 gross amount of power we must deduct that necessary to move the engine with 

 its supply of coals : this will reduce it at least to 1551bs. ; consequently, in the 

 one case we have a force of traction of 1251bs., at an expense of 186 farthings, 

 and, in the other, a force of 1551bs. at an expense of 158 farthings ; arid reducing 

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

 horse is -if =1.488, and of the locomotive engine, 1.019, or about as 147 is to 

 100. In this case, therefore, there appears to be a decided economy in the use 

 of the steam-engine, and accordingly its application has become very general, 

 and is becoming more so every day. 



Let us now examine what alterations are requisite, before w r e can apply these 

 calculations to the case of draught upon common roads. Supposing both species 

 of power equally convenient and applicable, and confining our observations 

 merely to the amount 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 engine. 



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 will 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 possibly be elsewhere. 



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

 increased effect of the weight of the engine. On a railway with the carriage, 

 as now constructed, the force of traction is not much more than -^ or ^ s 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 required to move a well- constructed carriage 

 cannot be estimated in practice, at less, even when the roads are in good repair, 

 than -^ ; 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 11201bs. per horse power, and ^ of 1120 is nearly 45lbs., which we have to 

 deduct from the gross power of the engine, arid which leaves only 121 fibs, as 

 the available power. The proportional expense of the horse and the steam- 

 engine is now therefore about as 115 to 100, and this without taking into account 

 the causes of increased expenditure already alluded to as regards the prime cost, 

 the repairs, and the consumption of fuel. From these calculations it would 

 appear, that even if mechanical power was found as convenient and applicable in 

 practice as horse power, still no great economy can be expected from the 



