# Report from the Select Committee on Steam Carriages/Gurney2

Veneris, 5$^o$ die Augusti, 1831.
Mr. Goldsworthy Gurney, again called in; and Examined.
Will you give in the Statement that you were directed to produce on the last Examination?—I Will.
[The Witness delivered in the Same.]
Calculation as to the relative Expences betwixt Horse and Steam Power for Locomotion.
In order to estimate the comparative expence between Horse and Steam Power for drawing Carriages on common roads, I will take the relative expence on 100 miles of ground for working a common stage coach by steam and by horses.
The first cost, wear and tear of the coach drawn, in every respect is the same in both cases.
The expence of men to manage is about the same also. In one case there is a coachman and guard; in the other, an engineer and director.
Government duty and turnpike tolls must also be considered the same.
It remains then to show the difference in the expence of Power only; viz, betwixt the expence of Horses and the expence of Steam. First in the outlay, on 100 miles of ground. To work a coach well with horses 100 miles up and 100 miles down once a day, will require 100 horses. A horse a mile is the present calculation for doing the work. If these bosses be taken at £20 or £30 per horse, or say £95, it will amount to £2,500. Three Steam Carriages will do the same work, and the expence of these will be about £500 each, or £1,500 for the three. A saving will consequently be effected in the first outlay of £1,000 in capital.
The wear and tear of horses may be estimated at about £5 each per annum on the 100 horses; viz. £500 per annum.
The wear and tear of the three Steam towing Carriages will not exceed £100 each per Annum; £300 for the three; saving in wear and tear, £200.
The expence of shoeing, keep, provision, attendance, harness, &c. is per day somewhere about 3s. each, or £15 upon the 100 horses.
The expence of fuel for two carriages, one up and the other down, doing the same work, will be that of 100 bushels of coke at 6d. per bushel, say £2 10.
Or if we take 1s. per mile per horse power, it will be about the same. The expence of fuel for the Steam Carriage will be, on an average throughout England, about 3d. In some coal districts it will not exceed 1d. per mile; while in other situations it will amount to 6d.
​I have not taken into this estimate the expence of stables, which is considerable when compared with sheds for coke and water.
From these data I conclude the Carriage may be worked by Steam at one-fifth the expence of Horses.
Have you any additional Evidence to give to the Committee, on points which you have considered after your last examination?—I have no further Evidence in connection with the practicability of the Carriage.
Would you wish to explain your former Evidence, or to give any additional Evidence upon the subject?—On looking over the Evidence I find it correct; I should observe, in explanation, that at 3s. a day I have taken in the wear and tear of the horses, and the attendance, and the fuel.
How long are your boilers calculated to last?—About three years fair treatment.
How frequently do they require examination?—Once a fortnight or three weeks ; it depends on the situations where they work, in some situations where lime is held in solution in the water in large quantities, they require cleaning oftener, but in other situations where there is very little earthy matter held in solution they will run for a month or two months.
Is there a facility of cleaning them?—There is, from recent improvements in cleaning, very great facility.
Is there any expence attendant on the operation of cleaning?—One day's work of a labourer, their not requiring an engineer.
​You have stated in your former Evidence that it would be unjust to put a toll on Steam Carriages according to the nominal horse power of the Engines, will you state why it would be unjust to put a toll in that way?—Because I conceive at present there is no standard by which we can fix a horse power:.
Will you state to the Committee the variations of rate at which the different Engineers have calculated horse power?—The most generally received standard is 180 pounds at two miles an hour, say from 150 to 200.
Could there be any fair system of toll established by the length of stroke, and the area of the piston?—I think not; the length of stroke and the area of piston will give power in proportion to the pressure of the steam upon it; the apparatus for supplying or generating the necessary steam would vary considerably in weight in different Engines; and therefore the weight of different Engines would vary so much perhaps as three times or four times.
Would there be any objection to placing toll on an Engine according to its greatest power of working?—I think it would be very difficult to ascertain its greatest power of working; it might be done, but it would be very inconvenient.
Are there no means of ascertaining the average power of working?—Horse-power is very arbitrary; the best standard which I can give, is the evaporation of water, and I should say that the evaporation of nine gallons of water in an hour, ought to be equivalent to one horse-power. One Engineer will apply the steam with more effect from nine gallons of water, and with more general advantage than another; nine gallons may be taken as an average.
What is the diameter of your cylinder, and what the length of stroke?—I believe I have given the length of stroke in my former Evidence, but not the diameter of the cylinder. The diameter of the cylinder now used is about eight inches, offering 64 circular inches area on the piston.
Is there not on those engines an average rate of expenditure, not speaking with mathematical ​certainty; is there; riot the means of calculating pretty well the expenditure necessary to work them? The expence of fuel for working them is well ascertained.
Having ascertained that it will evaporate nine gallons of water in an hour, you come pretty nearly to the expenditure of one horse power?—It does not follow in all cases, that one horse power will be practically produced from pine gallons; and on the other hand may state, that I have seen a horse power produced from five and six gallons.
At what pressure?—It does not signify much at what pressure.
You say that the evaporation of nine gallons of water is equal to one horse power; does it not make a difference according to the pressure?—This is a point unsettled at present by Engineers; some advocate high, others low pressure.
You have stated, that if you wished to increase the power of your Engine, you would increase the weight of it, and decrease the size of the wheels?—It might be done either way; the union of the two is not necessary as far as regards the intensity of power; quantity of power must be produced by an increase of weight, or by some increased or rapid formation of steam.
What is the weight of a loaded waggon, with horses?—At this moment I am not prepared to give an accurate answer, but I should think six tons.
Does that include the weight of the horses?—No.
What should you judge to be the weight of the horse usually attached?—From 14 to 16 cwt. each horse.
Would not you, by increasing the size of the cylinder, increase your power?—Yes, in direct proportion with the increase of the area.
What objection do you see to increasing the size of your cylinder, and applying it to a large waggon, so as to use Steam Carriages for the mere carriage of goods?—I think the difficulty and objection lies in the management practically, it would be difficult in our present state of knowledge and experience to manage a large cylinder very rapidly on the road; but I ​see no other obstacle to great speed; there is no theoretical difficulty. I would wish to state, in connection with my former Evidence with respect to fuel for working slowly heavy Carriages, that my opinion was founded on some peculiar laws of momentum lately observed; it is well known that one Engine, when worked at a given rate, works expansively; that an Engine working at a quicker rate, if a piston only travels half a mile an hour, or 50 feet a minute, it will require more fuel for it to do a given work, than if working at 200 feet a minute,
Is not the momentum gained by greater velocity an accumulation of power?—I think the advantage gained by certain rapidity of action, arises from the inequalities of the road being overbalanced by the momentum of the Carriage; when the Carriage travels slowly, every inequality, every stone or slight obstacle partly destroys the momentum, but at a certain speed it overcomes them; there is no actual gain of power by momentum; it is only an accumulation very much like that in a common fly-wheel; and in a Carriage on a common road, it acts on inequalities as a fly-wheel does, in overcoming unequal obstacles in machinery.
You use coke only?—We occasionally may use charcoal, but very seldom.
What is the proportion in price and what in value between coal and coke?—I think one bushel of coals is equal in raising steam to two bushels of coke.
What is the difference of price on the average?—The difference of price is, I think, about two-thirds.
Then there would be a loss as compared together in using coke?—Coals would be much cheaper than coke, but that loss in the expence of fuel we are disposed to suffer rather than produce a nuisance on the road by smoke.
Do you conceive that there can be no mode of escaping that by any smoke-consuming apparatus?—I know of no mode that is likely to succeed, nor do I conceive that it is possible to make such a combustion of coals that is likely to consume all the sublimated or volatilized matter; the consuming of smoke ​or the combustion of smoke is prevented principally by the particles being mechanically mixed with or surrounded by carbonic acid gas. I believe it not to be chemically combined.
Would not the motion of the Carriage and the current of air that is produced by going quickly through the air, give great facility in the application of a smoke-consuming apparatus?—If the consumption of smoke depended on the presence of oxygen gas or atmospheric air which contains it, I think it would; but on my previous reasoning, I do not think the consumption of smoke would be effected by any quantity of atmospheric air. I have made several very extensive experiments on this subject, and the only experiment that I have succeeded in, was by passing it through sand mixed with quick lime, by which the carbonic acid was absorbed, and the smoke as it passed through the mixture rendered combustible; the carbonic acid was removed to a considerable extent, and left the carbonic oxyde and hydrogen gas in such a free state as to be combustible.
Of what materials are your propelling wheels?—The same as a common stage coach wheel.
Are the wheels of the Carriage drawn nearly of equal diameter with the wheels of your drawing Carriage?—Rather less; the diameter of the wheels of the drawing Carriage is about five feet, and the ordinary diameter of a stage coach that is drawn is about four feet six.
From the experiments you have made, supposing the drawing Carriage and the Carriage drawn were of equal weights, what do you think would be the different proportion of weight on the wheels?—None.
Do you speak that with any certainty?—Yes, I do. I have taken the loss of iron upon coaches after knowing the number of miles they had travelled over, and the loss of iron on the Steam Carriage, and the number of miles it had travelled over, and find that the love in both cases bore the same proportion.
Is coke alone used on the railways in the locomotive Engines?—On the Manchester and Liverpool ​rail-road, I believe there is a clause in their Act to prevent any nuisance being made by smoke, and coke is therefore used; but in the ordinary rail-roads in Wales and other places, coal is used.
In what part of your Engine is your safety valve situated?—It is situated at the option of the Engineer; frequently in the steam pipe leading from the boiler to the Carriage, most generally; so that the steam as it passes through that pipe may lift the safety valve, or it may go to the Engine, as the state of pressure shall determine.
Do you make use of one or two safety valves?—Only one, I occasionally use two, but we now use only one.
If your Carriages were brought into general use, would you suggest that two safety valves should be required, one out of the reach of the Engineer to prevent accidents occurring from racing, or other causes which could induce the guide to increase the pressure of Steam?—I should recommend one being locked, and an Inspector being appointed to examine it every journey. Perhaps I may be allowed to make an observation or two with respect to the bursting of boilers, which subject, I believe, is now under consideration. From experiments which I have made in connection with this subject, I am led to believe that the bursting of boilers is not always occasioned by pressure of steam. I have discovered that at a certain degree of temperature and under certain circumstances, when water is decomposed, that the hydrogen is often formed into a new state of combination with oxygen and nitrogen gas, which compound is exceedingly explosive; so much so, that I believe scarcely any provision that we can make in the shape of a Safety valve, would protect the vessel. This was a subject which I was led to some time ago, from some observations which I had made on the combinations of oxygen and hydrogen only. I had some conversation with Gay Lussac on this subject, and he was of the same opinion with myself, particularly that there were different chemical compounds of hydrogen and oxygen gasses which at present were not ​acknowledged. The only one acknowledged in this country is that forming water. A compound of two proportions in volume of oxygen and two of hydrogen, has been chemically combined in Paris, although I believe we never have succeeded publicly in this country.—This compound was highly explosive when brought in contact with certain substances.
It would be by expansion?—By chemical contact; if brought into contact with certain substances, it would be so affected as to produce explosion. I have reason to believe from some original experiments, that there is a compound of these elements produced under certain circumstances in steam boilers. The want of water in a boiler is favourable, in which case the temperature is raised and the compound formed; the bursting of boilers I believe frequently takes place, from this compound coming in contact with substances that will decompose it, and perhaps I might mention this fact, as it is a very interesting one, namely, that boilers often burst when the valves are known to blow at a pressure very considerably lower than the boiler has been proved to.
Does not that take place also when the water is in the boiler?—If the water is low in the boiler it will take place; if it is high, never.
Has it not frequently happened that boilers that were calculated for a higher pressure, have even burst at a lower pressure than they were intended for, when water is in them?—When water is high in them, never; but when it is so low in them as to form this chemical compound, it does. I would state a fact, which was mentioned to me by my friend Sir Anthony Carlisle, which throws considerable light upon the subject, and first led me to my suspicions and experiments respecting it. The case was, that a boiler at Mr. Meux's brewery, with an open top—a common cauldron—burst with a violent explosion. I believe one man was killed, and two very severely scalded. There was no cover at all on the vessel. This phenomenon, upon inquiry, appeared to be occasioned be gelatinous matter, forming a crust, a film, or blister, and prevented the contact of water with the bottom of the ​boiler; the bottom of the boiler, consequently, got hot; the compound I alluded to was formed, or the rupture of this film, and the sudden contact of water against the hot surface below, produced such an immense and sudden volume of steam that it burst the boiler. I would explain it by saying it was analagous to the bursting of a gun, in which case an ounce or two of shot is placed only against the charge; whenever there is a sudden formation of elastic matter, and there be ever so small a weight opposed, the shock will be very great, and a gun will frequently burst, though there is not an ounce of shot in it, and which charge may be considered in the light of a safety valve in this case.
What precautions have you taken in your boilers, that there may be no probability of their being without water?—This compound never forms without a certain raised temperature. Before this temperature, necessary for decomposition, takes place, it melts a fuseable compound alloy of metal, placed so as to allow of its escape; the matter formed escapes, and all danger is prevented.
Have you any precaution to prevent the water escaping out of your narrow tubes, by bubbles of steam?—Yes; that I would explain by reference to the first drawing, (No. 1.) which will show that the bubble of water, as it escapes from a tube in connection with a part of the boiler, is supplied simultaneously from the lower part of the tube, and a stream of water is thus made constantly to pass through.
Would not that stream of water act as a safety valve?—When there is water it is sufficient, but when water gets down in any boiler there is no safety valve that will protect it, and hence arise the inexplicable accidents that have occurred frequently in steam boats; the size of the boiler is the only protection without the safety alloy.
Have you any guage, or means of ascertaining when there is a deficiency of water in the boiler?—Yes; the melting of the safety plug, I would state, only takes place in cases of great negligence, or in cases of extremity. The gauge by which we ascertain the ​quantity of water in the boiler is the common glass guage, well known to those, acquainted with the subject.
Have you any guage to examine the intensity of the steam?—Yes, we have a piston which is forced oat in proportion to the pressure; in addition to the glass guages there are also stop cocks, so as to ascertain, by turning them, the actual height of water. I beg to state, that the safety plug has never, but four or five times, given way in all my experiments, and that has been in cases where we have been accidentally out of water in our tanks; no personal mischief can arise from such an accident. I am satisfied, without this plug an explosion would have taken place in some of the tubes. In large boilers, under those circumstances, inevitable destruction would have attended it.
Are you aware of the size of the cylinders and stroke of the Engines on the Manchester and Liverpool rail-road?—I believe them to be ten inches diameter, and about fourteen inches stroke. In some of the later Engines I believe they have been made of fourteen inches diameter, the stroke being the same; but I rather think that that size has been given up, and that they have returned again to the ten inches diameter.
What is the greatest weight, in proportion to its own weight, which any Carriage draws on a rail-road?—A Carriage was originally supposed to draw only three times its own weight on a rail-road; but in some experiments which I made in Wales with Mr. Crawshay, of Cwrfaithfa Castle, we found, in an experiment, that a Carriage draws thirty times its own weight. He has the minutes which we made upon the occasion; but I believe, in practice, they scarcely exceed five times, or from five to ten.
You have stated that in your Carriages you do not anticipate drawing more than the weight of the Engine?—Practically, on the common road, weight for weight. I explained in my former Evidence, that it was possible to do more under favourable circumstances; but circumstances vary so much on the ​common road, that we ought not to calculate on doing more than weight for weight.
The diameter of your steam-wheel is rather greater than the diameter of a carriage-wheel?—Yes; the size of the wheel I proportion to the Engine, so that the piston may work under the most favourable circumstances.
It is by experiment simply that you have arrived at your present size of cylinder?—Yes.
You stated in your former evidence, that you anticipated that passengers would be carried at one-half the rate by your Steam Carriages that they are by the common carriages, what difference in the ordinary expences of carriage would it make if you had a paved road for this purpose?—I think that it would reduce the expence to one-half again.
If there were properly paved roads, you conceive that passengers might be carried at one-fourth the present expence?—Not exactly; because the total expence includes the government duty, tolls, &c. as the same; but as far as the steam-power is concerned they would. These subjects have been inquired into by a mathematical friend of mine, and he has published the result of his inquiries, which I will take the liberty of delivering in.
[The witness delivered in the same.]
You have stated that in certain states of the road you find increased difficulty than in other states?—I have; and the difficulty arises, from a mechanical application of the steam simply; namely, in consequence of the road being in a greasy state, and the wheels therefore more easily slipping, and under the circumstances do not furnish so good a fulcrum for propelling.
Have you ever watched the operation of your Carriages in snow?—I have; I have used them both on snow and on ice. On ice, a very little roughing of the wheels is necessary, in the same manner as you rough horses, and little power is sufficient to propel the Carriage, because under those circumstances, the power to draw the weight is very considerably reduced, and ​therefore the full power of the Engine is not necessary to be exerted: in deep snow, there certainly is great difficulty; but I have no doubt that as the subject goes on improving, all those practical difficulties will be overcome.
The difficulty would be greater in your Carriage than in other Carriages, would it not?—I think not; I think the Carriage might be so constructed as to remove the difficulty.
Will you state the effect of ice below, and snow above, upon the action of your Carriages?—I have had occasion, in two or three instances, to use the Carriage under those circumstances, with a view of judging of the practical result of it; and I have not found any difficulty in its progress. The snow is pressed strongly under the wheel, becomes almost immoveable, and furnishes a good fulcrum for the wheel; a little preparation only is necessary, and a very little is sufficient to overcome any moderate obstacle of that kind. May I be allowed to give in to the Committee a scale of what I conceive to be an equitable toll on Steam Carriages? It is the same in principle as I gave in on my last examination, but is extended.
[The witness delivered in the same.]
To what width could you extend the tire, without any inconvenience to the working of your Carriage?—At present I cannot say to what limit it may be carried, but six inches would be no inconvenience.
Then your Carriage would go with six inches tire?—I think so; and under certain circumstances easier, where the crust of the road is hard.
Would not that depend very much upon the road?—It would; I would state general principles: I would submit to the consideration of the Committee, better to explain my meaning, that it frequently happens that a frost forms a crust sufficiently hard to support the weight of a Carriage a ton weight, but that it breaks under one or two tons; the power required to draw two Carriages respectively so circumstanced is so great, that I can give you no data for estimates off-hand; but it is evident, that the power of drawing a ​one-ton Carriage would be little compared with the proportion of power required to draw two. My answer to the question is, generally, as I find the public roads at this time.
To what velocity could you increase your present rate of travelling with your engine?—I have stated that the velocity is limited by practical experience only; theoretically it is limited only by quantity of steam; 12 miles, I think, we might keep up steadily, and run with great safety. The extreme rate that we have run is between 20 and 30 miles an hour. I stated in my former Evidence, that the Carriage when upset by Sir Charles Dance, was at that time going at 18 miles an hour, but no injury happened either to the machinery or the persons upon it; still I am of opinion, that that speed might be maintained with perfect safety by a little experience in practical management.
What are the practical objections to going at that rate?—I think the principal objections are want of knowledge and experience; I have been so many times disappointed in what theoretically I had imagined true, that I am afraid to give a decided opinion on subjects not practically proved.
Have you any thing further that you wish to state to the Committee?—I would state generally, in regard to the main improvements on Steam Engines, by which this country has been so much benefited, and the prospects of advantages arising from Steam Carriages, that they have almost always been in a direct ratio with that of removing horses; that the great and splendid improvements of Mr. Watt have generally been supposed to be principally connected with the separate condenser of the Steam Engine, and the saving of the fuel; but before Mr. Watt's day, we could empty our mines of water in Cornwall, and we could do a variety of other simple work by the Steam Engine, and so far the improvement of Mr. Watt was simply with respect to the saving of fuel; but I consider that the great national advantage arising from Mr. Watt's improvement, has been his application of the Steam Engine to machinery; and the extent of that advantage to the ​community has been in a direct proportion to the removal of horse power, a most unproductive labourer and a dead expence to the country. If this view of the subject be entertained, the application of steam to propelling Carriages on common roads will be as important above its application to machinery generally, as the number of horses employed in locomotion exceed those necessary to machinery, which bears no proportion with respect to each other. At Hounslow alone, there are at this moment upwards of 1000 horses employed in stage coaches and posting. On the Paddington Road, a distance of five miles only, there are upwards of 1000 horses employed at this moment. Throughout Great Britain it is almost impossible to say how many horses are employed, but should perhaps be within bounds if I were to say millions, in posting and stage coaches. If it is possible to remove those horses by an elementary power, which I firmly believe is practicable, the national advantage must be in proportion to the number of horses so removed; for if it is shown that one carriage horse can be removed from the road by the present state of Steam Carriages. I see no reason why every horse so employed should not be so removed. It has been decided that the consumption of a horse is equal to that necessary for eight individuals, so for every horse that is removed and is supplied by elementary power, we make way for the maintenance of eight individuals. If it is possible to carry the idea so far, and I see po objection to it, to do the principal work of horses by steam, or if it can be done by elementary power, the Committee may imagine to what extent we may provide for our increasing population. I think we may do much by political laws and enactments, but natural laws will do more, and when pointed out by the finger of Providence, may be made to provide for his wise dispensations. I firmly believe that the introduction of Steam Carriages will do more than any other thing for this country; I have always had this impression; I left an honourable and lucrative profession, in which I was extensively engaged, ​in order to attend to this subject, because I was convinced of its importance and practicability; I have always entertained the same idea as I do at present. Imperfections will exist in the machinery; but I conceive that the main points of difficulty have been removed by the experiments I have made, and that all those now remaining are practical difficulties, which will be removed by further experience; and if there is no cause opposed by the Legislature, or any other source. I will be bold to say, that in five years Steam Carriages will be generally employed throughout England. I have not hesitated, having these feelings, to devote all my time for the last six years to the subject, and am mentally recompensed by the present state of the subject. Private carriages also will be used. Under this opinion I have given directions for building a small one I expect it will go quicker, safer, more easily, and certainly more independently than a common carriage, because it does not need the food of a horse.
Do you apprehend much decrease in the price of your Engines?—I do, and I also anticipate that steam will be supplanted by the use of other elementary power; but I do not think that will take place in our day. I think that steam will be generally introduced, and that the public will feel the importance of it; and that scientific men will be directed to examine and employ in its stead other substances, and new compounds are continually turning up, and some will eventually be applied to mechanical purposes.
Do you believe that there will be other ways of raising steam?—I do not now speak of steam, but, certain compounds; I do not specify any particular compound at this moment; I state those generally which are known to produce power by chemical change; some peculiarly explosive and aëriform bodies for instance. I am informed that at present there are between 20 and 40 different Carriages building or about to be built by different persons, all of which have been occasioned principally by the decided journey which I took of 200 miles in 1829, and which ​convinced not only the public of its practicability, but also some of those very men who are now employed in this object, and who previously had laughed at the idea, and considered it chimerical.
In what particular point of machinery does your patent consist?—I have three patents, the first for the boiler, the second for the peculiar application of it, and the third for improvements that have been made since.
Do you anticipate much saving of fuel in your future experiments?—I do; I think the saving of fuel will be in proportion to the saving of water.
That is, that there will be a saving from the better application of the fuel and boiler?—Yes; and from the general improvements in machinery; for instance, it is an unsettled point at this moment whether a pressure of 20 lbs, to an inch, or 120 lbs, to an inch, it is not yet decided, which time will decide.
Do you cut off your steam, so as to work expansively?—Yes, we generally work expansively.
You have mentioned that various accidents had happened to the crank of the Engine, which were not accounted for; have you in contemplation to effect any change in the application of the power?—At present. I think the crank the most simple; in some of my first experiments I worked with a chain passing over two wheels from one to another; also by a rack and pinion, and various motions of that kind; but I think that nothing is equal to a crank, that also is the opinion of others besides myself. Upon the Liverpool Rail-road they first applied the power to the outside of the wheel, but they have come to my drawing (No. 3.) at last, and they now work by the crank on the axle; this practically confirms my opinion.—There is one observation which I would at this moment make in connection with my former Evidence. I have been frequently asked, what would happen in case of an accident happening to the guide or director, in case he falls asleep, or in case he is disengaged from his seat. I have provided for all those casualties, distant as they are, by making the valves of the Engine only remain in gear when the guide is in his ​ proper situation; the moment he is thrown off his seat, by accident or otherwise, the Engine instantly stops. Does that depend upon the guide's weight?-No; it is by his foot he keeps the valves down, and the effect on the Carriage when he takes it off is very singular; I merely mention that fact in connection with the practical detail and safety of the Carriage, the same contrivance, by simply lifting the foot, prevents the Carriage running down hill too quickly, and we do not require the complicated drags that were before used.