HINTS FOR HAULIERS.
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An Analysis of a Profitable Week's Work with a Four-tonner. The Operation of the Law of Averages.
SIX HUNDRED MILES (587 of them moneyearning) in five days makes good business, provided that the rate of pay, and its excess over expenditure. are sufficient to justify the exertion. I referred, in my notes last week, to a series of journeys covering this total distance, reported to me by a reader, and then promised that I would work out a profit and loss account.. Let us now see how it does work out.
The first run was from Sheffield to Edinburgh, with 5 tons up. The rate for this is 85s. a ton; ..total for the journey 221 5s. The next trip was from Edinburgh to Newcastle„ carrying 4t, tons, which, at 45s. a ton, will bring a revenue of 210 2s. 6d. A 4-ton load to Hull, the next stopping place, brings in 212 16s. at the standard rate of 64s. a ton. Similarly, from Hull to Sheffield, with 4 tons at 28s. a ton, means -a return of 25 12s. The total gross receipts, therefore, for this interesting circular tour amount. to 249. 15s. 6d. If we subtract the' clearing-house discount of 10 per cent. we arrive at 244 16s., which is the amount actually received by the haulier, of, as the contributor to this journal's humorous page might say : the incomings for an outgoing of 600 miles amount to very nearly 245. Is it worthwhile?
Now, the vehicle employed • on this particular journey happened to be a 4-t,onner, and the average running cost of such a vehicle—that is to say, the expenditure on fuel, lubricants.,. tyres and maintenance, together with an allowance for.depreciatien—is. 8.85d, per mile ; total for 600 : 222 2s,. 6d. The particular lorry which ran this trip may not have cost so much. It should not cost more, for, although I give the title of "average " to the running costs which I schedule from time to time in these articles, they are rather over the average than otherwise, and better
figures are frequently attainable. . I think we may reasonably be allowed to debit this job with a week's standing charges, namely, B39
25 19s. 6d. The driver was away for five nights, and hie, expenditure would certainly not be less than 22 ; probably it would amount to 22 10s. The total cost to the owner Of this 600 "miles is, therefore, 230 12s. 6d., and the mart on the job 214 3s. ad., which seems quite reasonable and, if subsequent weeks do not give a return much smaller, should satisfy the owner.
The Law of Averages, and its Working.
In a way' it is quaint, but none the loss true, that one of those things which is least understood by the average man is the meaning of average. My letter bag, and much of the contentious matter which appears on the "Opinions Page" of this journal, afford ample proof of this statement, if proof be asked. For the benefit of those readers who have not access to the former, and who may not always appreciate the significance of the latter, I cite also the daily papers which, from the middle of the day on, are popular only in proportion to the amount of betting and racing news which they disclose. No man, knowing nothing whatever of horses, will imagine that he is going to make money by betting if he appreciates in the least the working of the law of averages. ,My own immunity from any leaning whatever towards that form of entertainment is due entirely to the fact that I happen to have been born with a wholesome respect for and a wholehearted belief in that self-s.ame law. Its importance, in connection with what I have to say in these articles week by week is paramount. All our reckonings of profit and loss are based on averages, on averages calculated from information and experience gathered over a period of nearly a score of years, averages which I have, time and again, proved to be unassailable it theirpractical accuracy.
So far as the general reader is concerned, he comes most directly into contact with this matter in connection with the fuel consumption of his vehicles. The most absurd ideas are frequently entertained by tisers, and sometimes by other than users, as to the capacity of their machines for consuming many miles with the minimum flavouring of " essence," as our allies call petrol. The worst of it is these ideas are nearly always based upon evidence which, so far as the user is concerned, appears to be incontrovertible. It is, as a rule, the evidence of his own senses. To contradict it is to ask him to disbelieve his own eyes, and is merely calculated to give offence, instead of to convince him of his errors. Speaking of a 2-ton lorry, for example, an owner will say, with every belief in the truth of his statement, that ". she will do 16 miles per gallon." He has, or believes that he has, proof that such a performance has taken place, and from that time on bases his estimates of cost of running on that mileage per gallon,, which he treats as an average. Actually there are more than' half a score of chances c f error in his calculation, and at least half a dozen reasons why he must not treat the results as an average, even suppose that the particular experience which he has in mind happened to be correctly estimated, observed, and recorded—and this accuracy is a rare thing.
Errors in Measuring Fuel Consumption.
A poptttar method of estimating the fuel consumption of a vehicle is to traverse a well-known route, filling up with petrol at the start, and again at the finish, so as to ascertain a consumption during the journey. This to an inexperienced man is a method i 'which s chock-full of chances of error. 6. dozen such pitfalls are enumerated. Any one of them might have a serious effect upon the results of the test. The cumulative effect, supposing that every one of them occurred, and that the errors all tended in one direction, would be very considerable indeed, easily sufficient to astonish some of the most sophisticated experimenters, let alone those—and they are in the majority—who have not been fortunate enough to acquire, at any time during their lives, any idea as to the precautions which are necessary in connection with the most simple and straightforward of scientific investigation if a useful result is to accrue. I am sure that it will be interesting to imagine such a test, and to suppose, as I have suggested above, that all these errors have occurred and in such a manner that they affect the result in one direction. I propose to assume that such a test has taken place, and to try to discover what is the maximum discrepancy which would be likely to occur. I shall have to imagine that the preliminary experiment was carried out by just such a man as I have in mind, who has no experience whatever of experimental work, and who would therefore be quite likely to overlook every one of the. following possible sources of error.
We will take a, 2-ton lorry as our subject, and
suppose that, for the experiment, a fairly straightforward trip of 32 miles be covered, the lorry being loaded to capacity, and that the owner discovers that two gallons of petrol are required at the end of the journey to refill the tank to the 'same level as that at which the fuel stood when the journey was commenced. Our inexperienced experimentalist will, as the result of this trial, arrive at the conclusion that his lorry consumes 16 miles per gallon and that Ins total consumption during, say, a 4,000 miles contract would be 250 gallons, so that his fuel expense woutd amount to £25. We will try to discover how much iae might be wrong.
Fault No. I.—The journey is a one-day trip from point A to point B, and, although the user may not realize it, more of it is downhill than otherwise, B being actually 400 ft nearer the sea-level than A.
Fault No. 2.—The road surface is exceptionally good all the way_ Fault. No. 3.—A 12-mile-an-hour wind is blowing in the direction A to B throughout the journey.
Fault No. 4.—The trip is taken on a fine day when the road surfaces are dry, their good-condition at the same time precluding the presence of any coating of dust.
s Fault No. 5.—With a mistaken idea that, in this manner, a more accurate result would be obtained, a i quiet day is chosen for the trip when little traffic s on the road, so that, as it happened, a non-stop run was possible, there being actually no need whatever to use the brakes or to draw up until the journey was completed.
Fault No. 6.--Unusual care was taken with the throttle and ignition setting throughout the run so that the best possible result was actually obtained.
Fault No. 7.—The journey was carried out at a fairly even pace, no attempt being made to race anywhere.
Fault No. 8.—The speedometer was not checked for ,accuracy.
Fault No. 9--The alleged two gallons of petrol were merely the contents of a two-gallon can, not checked by rerneasurement to make sure that there had been no loss by leakage. Fault No. 10.—The machine was not on an even keel when either of the two observations of fuel level was made.
Fault No. 11.—The carburetter float chamber was quite dry at the start, but when the second observation was made was full of petrol.
Fault No. 12.—The vehicle, when the test was made, was in excellent trim throughout.
I hope to carry my arguments upon this subject a stage further in my next week's contribution.
THE SKOT011.