Speed and Power of the Locomotive

The following article is taken from a report in the Morning Herald on Monday 15th June 1846 by one of their staff reporters.

On Saturday, a public experiment for the purpose of “exhibiting the economy and tractive capacity of the broad gauge locomotive” was made on the Great Western line to and fro between London and Bristol. The experiment was an extremely valuable one, inasmuch as it is the first by which the Great Western Company have had it in their Power to test the capacity of the broad-gauge engine against that of the narrow-gauge engine.

In the experiments made on the Great North of England Railway under the superintendence of the gauge commissioners, the narrow gauge party worked their passenger trains of 50 and 80 tons with a locomotive that had had applied to it every improvement of which the narrow-gauge engine was considered to be capable to enable it to run at high velocities. But with 50 tons not more than a maximum velocity of 56 or 57 miles per hour, nor more than an average of about 48 miles per hour, could be attained, with 80 tons the maximum speed was about 50, and the average speed about 44 miles per hour.

At these speeds the motion of the engine was considered so dangerous that Professor Airy, one of the commissioners, declined to ride on her a second time. These speeds, it will be recollected were some miles per hour below those attained by the old broad-gauge engine upon similar gradients, and with similar loads. The world has now to compare them with the working of the new broadgauge engine - the first of a class - called the "Great Western," some details of the speed and power of which were given a few days since in the Morning Herald.

It will be found, from the comparative working given below, that the "Great Western" takes a passenger train of something more than one hundred tons at seven miles faster per hour than the new narrow-gauge locomotive propelled fifty tons; that she took the one hundred tons eleven miles faster per hour than the new narrow gauge engine carried the eighty tons, and that the work was done at less than half the cost at which the narrow gauge engine works.

The great national importance of these two facts must be evident to those who consider that the amount of railway traffic on the trunk lines of this country is increasing with extraordinary rapidity, that the London and Birmingham cannot manage its present traffic with the speed and regularity which the public have a right to expect, and that in

The Great Western

truth the propriety of constructing a second double line between Euston Square and Birmingham has for some title past been seriously contemplated.

Such a passenger train, as the "Great Western" can propel at a maximum speed of 70 and an average speed of about 50 miles per hour would require two or three narrow-gauge locomotives to propel it at 38 or 40 miles per hour. But the use of more than one engine has been pronounced by Sir Frederic Smith himself to be dangerous, and the expense of their use shuts them, in a commercial point of view, entirely out of comparison with the economical working of the new gauge engine.

The other important advantage of the “Great Western" arises from the amount of surplus power she would always have at command in running passenger trains of - say 80 tons, at an average rate of 45 miles hour; that is, from platform to platform - a performance utterly beyond anything that the new narrow-gauge engine could approach in the ordinary working of a train; This surplus power is of the most serious commercial advantage. It enables the engine driver to keep his time at the stations, and therefore ensures regularity, a matter of as much moment as speed itself.

Punctuality at stations in railroad travelling is the means of avoiding accidents, many of the most serious of which have, if I recollect rightly, arisen from trains being late between station and station. A locomotive like the "Great Western" - able, as she has proved herself, to run under a serious disadvantage, with 100 tons 116 miles (as she did down on Saturday), viz., from the 1st to the 117th mile post, including 9 minutes lost in stoppages, in 142 minutes, or at about 49 miles per hour, and to run she did likewise on Saturday) from the 118th to the 1st milepost, including upwards of 16 minutes' stoppages, in 111.7 minutes, or at 45 miles per hour, will, when she gets into proper order, be able to maintain in ordinary seasons

under ordinary circumstances an average speed of 50 miles per hour over a line of any length, whether it be one from London to Exeter, or from London to Edinburgh.

The train attached to the "Great Western," on Saturday consisted of ten carriages; seven of them were weighted with pig iron and the three other carriages took down a full complement of passengers. Among the gentlemen who went down were Mr. Charles Russell, M.P., the chairman. of the company; the Marquis of Chandos, Lord John Scott, Major General Pasley, R. F. Gower, Mr. W. Tothill, Mr. H. Simonds, Mr. John Roskell, Mr. Brunel, Mr. C. A. Saunders, Mr. D. Gooch, Capt. Claxton, Mr. T. Holroyd, &c.

The train started from Paddington at 11 hour 47 min 52 sec. It passed the 1st mile post at 11 hour 51min 1 sec., and came abreast of the 52nd mile (immediately after which the breaks were put on for the stoppage at Didcot), at 12 hour 45 min. 24 sec., running, therefore, the 51 miles, with a rise of 118 feet, in a few seconds over 54 minutes, at an average speed of upwards of 56 miles per hour. Perhaps the best mode in which the tractive power of the broad and narrow gauge engines can be conveyed to the mind of the reader, is that of placing in juxta-position the working of the new narrow-gauge engine with loads of 50 and of 80 tons, with that of the new broad-gauge engine with hundred tons.

I take the working of the narrow-gauge engines from the returns delivered into the gauge commissioners by the narrow-gauge party. I will first take the working of the narrow-gauge 50 tons train – See Table 1, columns 2 and 4 The 3rd and 4th columns in the above Table give the respective workings of the narrow-gauge engine with 80 tons, and of the broad-gauge engine with 1OO tons.

At Didcot a stoppage of 5 min. 15 seg. took place. The milepost beyond Didcot, viz., the 54th, was passed at 12 hour 54 min. 27 sec., and the 75th milepost, just after passing which the breaks were put on for the stoppage at Swindon, was reached at 1 hour 18 min. 6 sec., the distance of 21 miles having been passed over in 23 min. 39 sec., or at the average rate of upwards of 54 miles an hour.

At Swindon there was a stoppage of 4 min. 27 sec. The 78th milepost was passed at 1 hour 29 min. 30 sec., and the 98th milepost, which is a short distance on the Paddington side of the Box Tunnel, was reached at 1 hour 49 min. 26 sec., the 20 miles having therefore been accomplished in 19 min. 56 sec., or at upwards a mile per minute. The train came abreast of the 117th milepost at 2 hour 12 min. 3 see. This gives the time occupied in running the distance between the 78th and 117th as 42 min. 33 sec. for the 39 miles, or something like 53 miles per hour.

The maximum speed on the down journey was obtained between the 83rd and 92nd mile posts. From the 80th to 85th mile there is a falling gradient of eight feet per mile, and from the 85½th to about the 86½th mile there is a falling gradient of about 1 in 100, and a fall of eight feet per mile then reaches to about the 90½ mile post; a rising gradient of eight feet per mile then succeeds, and extends beyond the 92nd mile post. The train came abreast of the 83rd mile post at 1 hour 34 min. 56 sec., and passed the 92nd mile post at 1 hour 43 min 8 sec., performing the 10 miles in 9 min. and 8 Sec., or at an average speed of nearly 66 miles per hour. The 87th and 88th miles on a falling gradient of eight feet per mile were run over at the rate of sixty-nine miles per hour. I made the speed of the train over the 88th mile seventy miles and a half per hour.

Table 1 Comparison of Narrow and Broad Gauge Trains with loads of 50, 80 and 100 tons

Mile Narrow Narrow Broad posts. Gauge, Gauge Gauge with 50t. With 80t with 100t mph mph mph

2 3O 26 40 3 40 42 48 4 44 42 53 5 55 45 56 6 55 48 58 7 53 47 57 8 51 49 57 9 54 49 59 10 52 49 59 11 51 51 60 12 48 49 61 13 48 48 60 14 45 45 63 15 56 47 62 16 57 49 62 17 51 48 62 18 51 45 50 19 52 45 63 20 50 43 60 21 49 43 59 22 52 44 58 23 50 45 60 24 47 47 60 25 48 45 60 26 51 43 57 27 51 47 60 28 49 47 60 29 50 46 60 30 49 45 62 31 52 44 62 32 52 46 53 33 51 48 55 34 51 48 52 35 49 45 55 36 43 44 55 37 45 41 56 38 46 40 51 39 48 39 61 40 48 41 57 41 45 47 53 42 46 40 48 43 41 41 60

Mr. Samuda (the patentee of the atmospheric), who kept time the whole of both journeys, made the speed 70 miles 'per hour, while a gentleman who attended from one of the narrow gauge companies made it 69½ per hour; but these slight differences will always occur when running at such velocities, seeing that the variation of only half a second by two persons keeping time will give a decrease or an increase of more than half a mile per hour.

The performance of "The Great Western" was acknowledged by every person who went down by her to be an extraordinary one, far beyond anything that has hitherto been done by the most improved narrow-gauge engines; but the performance does not show the actual working power of the engine. The time occupied in starting from a state of rest till coming to a state of rest at Bristol was 2 hours 27 mins. 23 secs. The time lost while the train was at a state of rest at Didcot and Swindon was 7 mins. 39 secs., and the time lost in getting up speed when departing from, and reducing it when arriving at, the stations was 15 minutes.

This reduces the time during which the engine was exerting her average tractive capacity to 2 hours 4 mins. 24 secs and shows such capacity to have been equal to a journey of 118 miles, with 100 tons, in 124 minutes 24 seconds; or at the rate of about 57 miles per hour.

But the real working evaporative power of the engine was not obtained, and her pumps were, from some slight defect, which is being remedied, very far from effective. It appears that the blast was on for four and a quarter hours during the down and up journeys, and that 1298 cubic feet of water were evaporated. The evaporation was therefore equal to about 305 feet of water per hour.

Now the area of the heating surface of the firebox is about 170 feet, and by the theory of the builder of this very locomotive (Mr. Daniel Gooch) - a theory which was borne out by the engineering evidence given before the gauge commission - each foot of heating surface should evaporate two cubic feet of water per hour. Therefore, the engine worked below her power to an extent of something like the evaporation of 35 cubic feet of water per hour.

If this be correct the engine was working about 10 per cent, below her power. This may be accounted for by the large area of the blast pipe. In the details that I gave a few days since of the working of the engine with the usual express train, I stated that the blast pipe had been reduced. I believe that I was mistaken. The blast pipe is still a twelfth of the area of the cylinder. This is advantageous in some respects, but it reduces the evaporation to which such an engine would be equal if her blast pipe were reduced to the proportion which that of the celebrated lxion broad-gauge engine bears to her cylinder - viz., a sixteenth. The blast pipe of the new narrow-gauge engine that ran on the Great -North of England line was an eighteenth only of the area of her cylinder.

The defect in the pumps was another serious drawback to the development of the power of the engine. At Slough the pumps were out of order, and near the 31 mile-post they ceased to work; the consequence was that the pressure on the boiler was obliged to be reduced and the fire slackened for several miles till the pumps were got in to work again. The engineer , who was fearful of his pumps , from the existence of the defect already adverted to, started with the water in the tank nearly cold, and the consequence was that when the pumps were got to work after they had ceased to perform their functions, it was necessary that they should pump quickly into the boiler a large quantity of water nearly cold. This of course, tended to decrease the speed of engine.

A few minutes after the arrival of the experimental train at Bristol, the company partook of a very elegant déjeuner that had been prepared in the long room of the station. It was supplied by Mr. Niblett, the well-known proprietor of the White Lion Hotel. The turtle, hock, and champagne were - particularly to those who had been occupied by the dusty duty of timing the velocities of the engine - as acceptable as they were excellent. About 100 gentlemen sat down at table. Mr. C. Russell presided.

Upon the removal of the cloth the Chairman gave the "Health of the Queen; which was loyally responded to.

The Chairman then said—The next toast is one which you’re your presence here this day assures me you will receive with pleasure- It is, "Success to the Broad Gauge" (cheers). Gentlemen, it is the fashion, in the phraseology of the day, to call everything extraordinary a great fact. The AntiCorn Law League has been called a great fact. Now, I think that today we have witnessed a great fact (cheers ). The Great Western, new locomotive, most of you, I dare say, have inspected - it is in itself a great fact (hear). A train of 100, or nearly I believe, 110 tons, conveyed from London to Bristol in about 2 hours and 21 minutes is a great fact (cheers). The speed at which we have travelled, from 60 to 70 miles per hour, is another great fact and the ease, comfort, and the consciousness of safety you have experienced, is not only a great, but it is a very agreeable fact (cheers).

Gentlemen, this is the plain, this the practical answer which we give to all the assertions of the advocates of the narrow gauge about " the power evaporation" and "dead weight," and the various other arguments I was going to call them, by which it has been attempted to mystify and to falsify this question (cheers). This is the answer that I give to the report proceeding from the gauge commission.

Her Majesty's government, speaking through the enlightened President of the Board of Trade, has not thought fit to adopt the recommendations of the commissioners. It has not thought right to declare that the powers of enterprise, of invention, and of genius shall be limited within 4 feet 8½ inches (cheers). Gentlemen, what we have done today you have all experienced ; what we have yet