Experimenls on Screw Propellers in H. B. .~£ Steamer

In 1S47 and 1848, there were made by order of the British Admiralty, experiments on a number of screws applied to H. B. M. Steamer .Minx; and [ find in Bour~e's Treatise on the Screw Propeller, a table of these experiments, for the first time published. This table appears to me, in the eondfiion in which it is given, to bq of but little value to the practical engineer, and liable, without careful discrimination, to mislead him, It is accompanied by no account of the manner in which the experiments were conducted, no classification is attempted, nor are there any deductions drawn. I have, fl~erelbre, selected from those experiments in which flJe results a:e consistent wilh each other and with the nature of things-rejecting anomalies--such of the observed elements as were not contradictory, and from them have made my own calculations and drawn my own coneh~sions. The .31i~x was a vessel of the following dimensions, viz :

In 1S47 and 1848, there were made by order of the British Admiralty, experiments on a number of screws applied to H. B. M. Steamer .Minx; and [ find in Bour~e's Treatise on the Screw Propeller, a table of these experiments, for the first time published. This table appears to me, in the eondfiion in which it is given, to bq of but little value to the practical engineer, and liable, without careful discrimination, to mislead him, It is accompanied by no account of the manner in which the experiments were conducted, no classification is attempted, nor are there any deductions drawn. I have, fl~erelbre, selected from those experiments in which flJe results a:e consistent wilh each other and with the nature of things-rejecting anomalies--such of the observed elements as were not contradictory, and from them have made my own calculations and drawn my own coneh~sions.
The machinery consisted of two vertical, oscillating, condensing engines, geared so as to give the screws four revolutions for each double stroke of engines' pistons.
The trials were made in the Thames river, at a measured geographical mile of 608~ feet; the vessel being kept throughout at nearly the same draft of water. I The mean gross steam pressure in the engines' cylinders was ascertained by an indicator, and the dynamometer was applied to obtain the thrust of the screws. Now, the dynamometer measures simply the power applied to the propulsion of the vessel; that is, it measures that part of the total engine power which is expended in giving motion to the hull; and as it is evident that with the same vessel, under the same circum-stances~ greater speed can he obtained only by the application of greater 19" power to the hull, and greater in proportion to the cubes of the speeds, it follows that the dynamometer powers should be sensibly in the proportion of the cubes of the speeds within moderate limits : but the resuits, as given, show not only no fixed relation of tile dynamometer power to the speed, but frequently a much less speed, accompanied by a much greater power; the dynamometer results must, therelbre, be entirely rejected as erroneous.
The given number of revolutions made by the screw per minute, can doubtless be depended on as exact; and the steam pressure in the cylinders, as given by the indicator, can probably be depended on, not as strictly accurate, but as a pretty close approximation to the truth, as I find by testing, that in general the revolutions of the same screw in equal times, are nearly in the ratio of the square roots of the piston pressures~ which should be the ease.
The element most liable to error, and of the greatest importance, because its third power enters in the comparisons, is the speed of the vessel; an element obviously the most ditticult to determine with exactness.
As the speed of the vessel for the purpose of comparison must be the speed in smooth water, uninfluenced by wind, current, steering, or unequal fouling of the bottom, and as these causes vary on every trial, and as it is impossible lo ascertain their efIbcts accurately, there must always be some error in the element of speed--an error which can only be reduced to an insensible amount by taking the mean of a large number of trials; the greater the number the less wilt be the error. In the experilnents with the 3lflnx, the number of trials made with each screw appears to have been too few, and it would have been more satisfactory had the final results been the mean of a greater number of observations.
The distance run of one geographical mile was too short, as ~he slight error of only a few seconds in the times of passing the stakes at each end of the course, if made in the same direction, would wholly vitiate the result; for instance, the true speed of the vessel being supposed 8 miles per hour, there would be required 7½ minutes to run one mile; now, it' an error of only 5 seconds be made in the time at each stake, being called that much too late at commencing, and that much too soon at stopping, making an error of 10 seconds in all, then the mile, instead of being run in 7} minutes, would appear to be run in 7~ minutes, and the vessel's speed, which was really 8 miles per hour, would be given as 8'37 miles per hour; and as the cubes of the speeds are the measures of the eflbcts, this discrepancy would become enormously exaggerated in the final resuit.
No drawings or descriptions being given of the screws tried, it is impossible to know their exact configuration; they were probably of uniform length from the hub nearly to the periphery, and the helicoidal area was made equal, or nearly so, in the several screws, by "culti~.g otf lhe corners," as it is termed in Bourne's Table of the Experiments. It is not stated ~'hether the areas of the screws, as given in this table, are the projected areas on a plane at right angles to the axis, or the helicoidal areas; they cannot, however, be the former, as they are too large, even on the supposition that the length was uniform from hub to periphery. The screws experimented with were all two-bladed~ and of the same dia-meier, viz: 4 feet 6 inches. They consisted of four series : 1st, Screws of uniform pitch. 2d~ Screws of expanding pitch fore and aft, but of uniform pitch radially. 3d, Screws of expanding pitch radially, but of uniform pitch fore and aft. 4th, Screws of expanding pitch both fore and aft a0d radially. Each series will be considered separately.
Screws of Uniform Pitch.--The screws of uniform pitch were three in number, and had pitches of 5 feet 10 inches, 5 feet 6 inches, and 5 feet, ~'hich screws I shall call respectively A, B, and c. The screw, A, was modified by successively reducing its length by a plane at right angles to the axis, and experiments were made to ascertain the effect of each reduction.
With screw, A, (before modification,) six trials were made. Of these, the first two, made on the 4th and 5th June, 1847,I reject, as the results are too greatly inconsistent with the general results of the experiments, and too widely differing fl'om the results of the last four trials, which closely agree with each olhcr and with the general results; I therefore accept them. The mean of these four trials gives a slip of 37.3 per cent., fi'om which the extremes do not differ 1 per cent.
The first modification of screw, .% was made by reducing its length from 1 foot to 10 inches, and its helicoidal surface from 7"1 square feet to 5'97 square feet. The mean of three trials with this modification gave a slip of 39"6 per cent., from which the extremes diftbr by only ~oths of 1 per cent. This reduction in the length of the screw caused an increase (39.6-37.3 × loo_) in the slip of 2"3 per centum absolutely, or \ f7~3 6"2 / per centum relatively; or, in genera], decreasing the surface one-sixth increased the slip one-sixteenth. The second modification of screw, a, was made in the same direction and in the same manner as the first one, by cutting off 2 inches more, which reduced the length of the screw ti'om 1 foot to 8 inches, and lhe helicoidal surface fi'om 7"1 square feet to 4"93 square feet. With this modification, two trials were made, of which I reject the first, made 9th July, 1847, as the result is obviously erroneous; I accept the last trial, which gives a slip of 41"7 per centum. Tiffs red uction in the length of the screw caused an increased slip over that of screw, a, of (41"7~ 37"3 =) (4l'7--37"3x100)11"8 per eentum 4"4 per eentum absolutely, or 37"3 --r&aive]y; or, in general, decreasing the surface one-third increased the slip two-seventeenths. A further experiment was made August 17th, 1847, in the same direction .:rod manner, by reducing the length of the screw to 6 inches. Only one trial was made, and the result is so manifestly erroneous that I reject it.
With screw, ~, two trials were made, of which I reiect the last, made July 1st, 1848, as its result is greatly inconsistent with }he general results. I accept the first trial, which gave a slip of 34.8 per eentum.
With screw, e, three trials were made; the mean result gave a sllp of 31'6 per centum, from which the extremes do not differ 1 per centum.

2"24
Civil Engz~eer~ng.  ]f~ now, we compare the pitehes of screws, A, B, and c, (which are similar screws in all respects save pi{ch, having equal diameters, helicoidal areas, length and number of blades,) wid~ their slips respectively, we shall find that the slips are sensibly in the direct ratio of the pitches, as appears from the following :

Pitches.
8Iips. Screw a, 5"833, or 1'167 37-3, or D180 Ncrew n, 5-51)1), or 1"100 34'8, or 1-101 ~ercw c, . 5"0CO, or i'000 31'6, or 1"000 That tiffs shouhl be the truth, is manifest from the eonsi{ieration that the rotary velocity of similar screws with unequal pitches to advance equal distances in equal times, is in the direct ratio of the pitches; and as the moment of pressure is as the rotary velocity, it follows that the resistances of equal screw surfiaces will be as their rotary velocities, i. e., as their pitches inversely, the lessor pitch having the greater resistance.
There remains to determine file relative economical efl]ciencies of the screws of uniform pitch. }'or this purpose, the horse powers developed by the engines will be taken as the expressions for the powers, and the cubes of the vessel's speed fi}r the measures of the ett~ets. The effects being divided by the powers, the quotients ;rill represent the relative economical efllcieBcies. 1"0700 "i~-0-9 = 1'018 2.
1"0930 1 0498 Screw e. 205"56 or 1'0412---,%576 or 1"0301 and 1'03013=1"0930 and ~*0~ " " From the above we perceive that with similar screws, omitting the modilications of screw a, there resulted an increased efficiency from each decrease of the pitch. This increased efficiency couhl only have arisen from the decreased slip of the screws wfih lesser pitches, and as the helicoidal areas of the screws were the same, the fi'ictions of the screw surfaces on the water must have been nearly equal, but a little greater with the screws of lesser pitch, on account of their greater helical speed. Now, as slip is a measure of the loss of usothl effect, that loss should be in the direct ratio of the slip, as will appear from the following considerations : As pressure and resistance are equal anti in opposite directions, a pressure equal to the resistance of the vessel is always experienced by the water on which the screw acts propulsively; but the amount of power expended is proportional to the resistances moved and the distances through which they are moved in the same time. Now, supposing the screw to slip or recede one-fourth of its pitch per revolution by the yielding of the water on which it acts; that is to say, that per revolution it moves the vessel through but three-fourths of the pitch, instead of through the whole pitch, as it woukt do were there no slip; and, as pressure and resistance are equal and in opposite directions, there is the same pressure exerted by the screw upon the receding water as there is exerted by it on the advancing vessel; but in the supposed ease of slip, the water acted on or pressed by the screw is moved a distance that can be represented by 1 in the same time that the vesseel is moved a distance that can be represented by 3, the whole distance moved being represented by .4, equal to the pitch of the screw. Calling the pressure on the engine p~ston 1, the total power developed by the engine can be represented by 1 X 4 =4, of which 1 X 1--1 represents the amount expended on the slip, or one-fourth of the total power for a slip of one-fourlh; while I x 3 =3 represents the amount of power expended in overcoming the resistanees of the vessel, or three-fourths of the total power developed. It is thus plain that the loss of useful effect caused by slip, is as the slip. It must be distinctly understood that lhe loss of useful eflbct caused by a slip of 25 per cent. is 25 per cent. of the gross or total power developed by the engines, and not '25 per cent. of what remains of the total power, after Civ'd ~n= za, eer~g.
de(lueting those fractions of it required for working lhe engines atone, and overcoming the friction of the load; for it is evident that at each revolution, 25 per centum of' the power required for working the engines a/one~ 25 per eentum of the power required for overeoming the friction of the load, 2~0 per centum of lhe power required tbr overeomingthe friction of the screw surfi~ee on the waler~ and 25 per eentum of the power required tbr l)ropelli~)g Ihe simple hull, makizJg a total of 25 per centum of the whole power developed by the engin% ,s lost by slip; tot, by eonsequence of the slip, each of these fi'actions or divisions of the total power has to be exerted 25 per centum l(mge~' to produce the same result; that is, to cause the vessel to go lhe length of the pitch instead of the length of'thrce-tburths of Ihe pitch~ than would be required were there no slip; and althouglb to make a revolution in the same time with slip, requires less piston lwessure than to make the same revolution withont slip, yet the useful eIIbet will a]so be proportionably less, as the vessel will be driven in the same time through a 1,.ss (listance by the amount of slip. To nbtain the same uscfcJ] eilbct, lhat is, to drive the vessel through equal distances in equal limes, the engines i, lhe case of slip must be worked at a pr~portional@ higher speed, wt~ich again requires a proportionably higher pislon pressure, so ibat to drive the vessel equal distances in equal lim~.s, wilh and without slip, the pislon pressures will have to be the same, but the speed of the engine, and consequently the power exerted, must be greater in the direet pl'opo~'li<n of the slip. On the above reasoning, we shrm/d lind the relative effieieney of the diftbrent screws wilh equal surfaces to be sensibly in the proportion of the slips. Applying this, the following appears to he the correspondence : Screw e has 3.9 per eentum less slip than screw n, and 3"l per centum more efficiency.
" " " 5"7 " " " a~ " 5"0 " " In the case oftt{e same screw with reduced surfaces, this law will he mo0ified, ~}/oln the fact that the reduced surface has decreased the amount of h'ietion of the screw on the waler; therefore, the relative e~ficieney of the same screw wflh decreased sm6meswill be in a higher ratio than the ratio of'the slips. Applying this, we have the fbllowing: lsl ]lw~ ;fieal o z.
Screw ~t has 6.9 per centum more slip than screw ,, and 4"7 per eentum less efficiency.
To be Continued.

Comparison between E~glish and .~merican Railway .Management.*
At a time when a parliamentmy committee is sitting on railway poliey~ it appears opportune to bring before shareholders whatever evidence is calculated to assist in arriving at correct conclusions. The position of railway administration in England at ttle present moment is this: it is assumed by railway directors to be pertbct; its perfeclion is very much doubted by slmreholders and the public. The former have an idea that every care is not taken fi)r economy, the latter that every care is not taken for public safety. The directors claim implicit confidence in their management, on account of the purity of their motives; the shareholders think that every respect may be paid to motives, but that a salutary investigation may be made into lhe details of management. We have always upheld this principle, and acting upon it we shall take advantage of an important public document .just issued in the United States, to institute a comparison between English and American management. The extravagance of one line may be dcfe,ded or palliated by the greater extravagance of another line; but the experience of a remote system may be accepted as impartial evidence, and it may better guide us in arriving at results. Here a certain set of engineers have given the same general character to the railway system and management; the school of Stephenson has become the school of Engkmd, and there has been little disposition to authorize anything which did not bear the stamp of legitimacy, as authoritatively imposed by the arbiters of railway expenditure. Ia the United States it has been dift~rent; the~'e has not been that blind following of the high and mighty in engineering, and as there has not been a body of open-mouthed and open-pursed shareholders to draw upon, unlimited economy, and it may be.said necessity, has in many eases been allowed to have some voice. Hence we may expect to get some evidence, which, though not arising from identical circumstances, may throw light on the case, or even, as being of a negative character, may determine the course of the investigation.
The documents before us are included in the report of Mr. McAlpine, the State Engineer of New York, in pm'suanee of a recent law that passed in 1,'350, and although the operation of the system of returns is not yet eomplete, a large mass of valuable statistical information is brought together, and the deductions are very carefully drawn. When we state that the length of railways embraced in these returns is between 1800 and 2000 miles, it will be seen the extent is ample for comparison. The circumstances, to% of New York State admit of a better comparison than those of other parts of America. The country is not throughout so thickly peopled as England; but there is a metropolitan population in New York City of 600,000, and there are many populous towns. There are districts at~proaching Scotland and Wales in population, and lhere are large seats of manufacture, and in some places an enormous transit trade. Thus there is a great variety of character in the traffic conditions, in some cases approaching those of our wealthy and thriving districts, in others going as low as the poorest.parts of the Highlands or Welsh mountains. Some might reject the comparison for these latter circumstances, but they are iudeed those whMJ claim most attention. In these islands a total population ¢~I' :]O,O00,OO'O have 7000 miles of railway; in INew York a lmpuluti,m of :3,0l)9,0',)0 have 2.000 miles of railway. This is a proposition not lightly lo be set aside without investigation. In h'eland 6,000,000 of pe,q~h', b;~vc, oae-third of the length of railway possessed by half the p,.~pul,~lion in New Yock, or one-sixth of/he supply. The case of Scotland is ve~wrally better, tile same population as New York having half" the lelJgltl of r'.filw~Lv.
The passeng(+r tr~LiIie on i900 miles of railway in 1852 was 7,440,653, ..... ~5S '-~ which gave an and the nt, mbcr of miles ,'un. ,3I.~,,,, , ,.>~v, average mile. age per passenger oI 46 miles, h~ lc;)1, the average distance travelled by each passenger "a't~s 47 miles; so that from discrepancies in the returns some of the li:~ures must be received with caution; but Ibis may be taken as a thir averag'e. This rate is t:ar above the European standard, ;is the average rate in England aim Belgium is only about one-half of the above. The American returns include little of what is known as short or omnibus traftic; while from lhc gceut extet~t of" the country and the widely scattered population, for which railways afIbrd tile most convenient transit, the distance of tile ,i(,u,n,'ys is gr~mter than here. The returns like. wise include a large prol)ortioa of through emigrant traffic to the far West. The average sugg{'sts some interesting retlecfions; first, that the American traffic is not to such a {,rcut prol)Ol'tion as ours intermediate; and, second, that a railway system can be caMed out where the average mileage of each passenger is 46 miles, as must be the case in some thinly peopled colonies and eountries requiring great length of railway. This illustration will be ibund useful in reference to the Canadian railways~ the traffic of which is little understood here.
The average speed of the passenger trains is given as 26,} miles per hour, but this seems to be the speed ,a.ithout stoppages. At any rate, it is not a very high speed, but it is found suitable for a large proportion of the traffic. In this eounh'y, the question has been little considered how thr low speeds and cheap fares can be made to work profitably, exeept so thr as the Irish lines are concerned, though there the tendency is towards increasing the speed. In New York the emigrant traffic to Canada and the West is carried at very low rates, and it is contemplated to do the same on the Great Canadian trunk.
The average number of passengers in a train is returned at 7"7.6, the number of trains per dav bein,* c, enerall~ much less than in this country. lhe great endeavor in the l.rnited States is to give the public low fares, and the Companies a low rate of expenditure, and every thing is directed upon these two principles, which are made to work together. By running ti~w trains, at reasonable speeds, and by attending to the construction of the carriages, much economy is obtained. The American carriage being, as is well known, on a larger scale than here, and allowing of internal communication, admit of being worked cheaper with respect to the staff on the line and in the stations, and is effectively more convenient to the public than the English railway carriage. This is a subject well worfl~y of inquiry, as much of the economy of American railways depends upon it~ but at present we tan only brielly refer to it. The effect is to reduce English and ./tmerican _Railway Management.
$29 the expenses of fixed stations, and to allow of passengers being worked from places where, on the English system, a station could not be maintaiaed, hastead of a staff distributed over twenty stations, as here, the stall" in America travels with the trains~ and the stations~ buildings, and equipments are consequently of a minor character. On the other hand~ whez~ever it is desirable to set down or take up a large or small number of passengers at a given spot not usually worked to as a station, nothing is necessary but to stop the train, like an old stage coach, and the requisite station staff is forthcoming. There are many places where there is a market traIiic once a week, tbr which a fixed station staffwould be required on such occasions, and with the privilege of keeping their hands in their own pockets, and dipping into the pockets of the shareholders the greater part of the week, and which must in England be neglected or worked at a loss. Of course, a staff" proportional to the trains will~ ne~'ertheless, be at times in excess of the traffic, but by no means correspondent to a fixed station staff.
The clement of cost, we have frequenlly had occasion to point out, is the foundation of traffic workiz~g, upon which depends lhe relation of returns to expenditure, and to a great degree the realization of a dirt-(lend. It is true enough, that where there is an enormous traffic it may be able to meet an enormous outlay for construction; but on the other hand, a moderate outlay is safer to receive a return. We have shown that the length of line in New York State is far above our standard, and we may observe that it brings a very handsome return, and this in a thir+ly peopled country. The whole cost, however, of 1819 miles is 884,034,456. For the reduction of the various sums from American to English values, we shall take the dollar at 50d.; that is, the cent at one halt)enny, which is sufficient to meet the requirements of the ease, and which will give us as the whole cost 17,500,000/. The average cost per mile of a single line of rails is ,~36,701, or 7500l. Upon the question o~' comparative cost, we shall not now dwell, only so fhr as it iniluences the question of fare.
h is ob,,ious that lines costing 75001. per mile can carry much cheaper than li~es that cost live or eight times as much, unless the iatter are qualiiied to carry a greater tratthc. A double line effects this, but still there is the diffbrence between 15,000/., the American standard for a double line, and the ,nuch larger cost of' most of our English lines. We take the cost of a double line at double the single track, which we believe is about lair in the llnited States. It" then a double line in lhe United States would cost 15,000/., it can carry at one-third the fare of a lille costing 45,000l, and pay as good a profit, and it is this question of ~ilre which, as a further step in the progress, influences traffic.
The working of a li,nestane quarry is as good an example for working out tratIic sums as can be found. Taking the cost c~f the limestone at five shillings per ton, aml the price which lhe farmer or other consumer can aff~rd to pay, or that which is limited by competition, to be ten shillings, then fi~,e shillings remaining" for cost of conveyance, the distance to which the lime can be carried will be limited by the rate of conveyance. If the rate he sixF)enee per mile, then the stone can be carried only 10 miles; if threepence, 20 miles; but it" one-penny, then 60 miles, To the earliers ¥OL. X.)2Vl.~'l'ui~zl~ S~:l~l~s. --No. 4,~OcToI~I~R, 1853, 20 it may seem indifferent whether they carry the stone ten miles or slxty~ seeing that they receive in either case tlve shillings; but if the)" truly look at their interests, it will suggest itself that the lowest fare ~hich is remunerative to them is the one which will bring the greatest return. With a distance run of ten miles, tile area of eonsumption and di.~tribution will be over a circle of ten miles radius, or 20 miles diameter; but with a distance run of 60 miles or 120 miles diameter, the area would be vastly increased. Practically, of course, the whole theoretical area is not obtain-ed9 because there are natural or other bounds to traffic. Thus, in the case cited, a neighboring stone quarry wilt constitute a bound at five miles' distance, though in other directions the radius may extend to 60 miles. The object, therefbre, practically, is so to adjust the rate of conveyance as to secure the maximum amount of ineomeand of profit. We need scarcely say that traffic managers in this country are seldom guided by such eonsiderations. At one time they put on prohibitory high rates on articles which will riot bear them; qt other times they engage in foolish competition with other companies, and put unremunerative rales on articles which can bear any amount of charg% and do not feel the benefit of the reduction. With regard to passengers, applying the above principle is equally applicable, though the tbrm is varied. Traffic managers can understand that coal and limestone are influenced in their consumption by the rate of charges, inasmuch as they proceed from a place; but they do not seem to understand the converse, how when the traftic goes to a place, the same law operates. Let its take the ease of Birmingham or Cheltenham. The eonsmnption of Birmingham goods is general throughout the country, and the tradesman wilt resort to Birmingham if he can do so with advantage to himself. This depends upon the rate of fare added to his other expenses, and being part of the margin of profit or loss on his operations. If ten shillings be the amount which he ean afford to spend on traveling to Birmingham, he will travel so far as ten shillings will earl S him, and this depends on the railway companies; beyond that sum he will not travel at all. Pleasure traffic is not of the same precise nature, but is dependent on the same general law, and the area of the Cheltenham traffic is as nmch dependent on the rate of railway fare as its )'early fluctuation is on the state of the country.
It will be seen that from certain districts a railway witl receive no i,> come at all, nor can it receive any unless its rate of fare will make it remunerative or practicable to the traveler. The hardwareman or ironmonger will visit Birmingham, Sheffield, or Wolverhampton, and the elothman will visit Leeds or Bradtbrd, if his transactions will bear it, and not without; and we need scarcely say that as matters stand, tile tradesman in the north of this island, or in the provinees of the sister island, does not think of visiting the places named for purposes of business.
The development of passenger traffic aftiects goods traffic in most articles, and the two work together, so that moderate passenger fares are of more importance than moderate goods rates. Coal, it is true, may be sent tc~ market in hundreds of thousands of tons with little personal supervision; but all kinds of merchandise and pareels traffic require much personal inlercourse, and this, notwithstanding cheap rates of postage and telegraph communications. Looking at all these circumstances, we cannot but feel that railway traffic in this country is far from hearing its full results, and has not reached a complete development.
The traffic of" the United States rests, it will be seen, on a sound basis, so far as the cost of line is concerned, for it is not difficult to get a traffic ibr a line costing 7500l. a mile, even though the per centage of working should prove very high. Upon such a cost we may expect low fares, and indeed we find them.
Oil a very few lines in New York, and those short ones only, do we find a first class fare of lid. This is the maximum, and seems to be an enormous rate. The ord'~aary first class fare is our parliamentary one of one penny pet' mile. What do our chairmen and shareholders, who exclaim against parliamentary trains, and call out for high fares, think Of that. ~t Let them imagine, if they can, the practicability of working a railway at such tares, paying 6 to 7 per cent. oa debenture debt, and higher dividends. Incredible as they may think it, it will be done in these countries as well as by our brethren beyond the Atlantic, and although engineers pronounce it impossible to make cheap lines, there will be plenty of them before many years are over.
Second class fares, properly speaking, are not found on most of the lines, the first class lares being so moderate that a uniform rate can be charged, and there is no necessity to talk of turning decent coated men out of second or third class carriages, adopting dirty tricks to prevent the public'from traveling according to their means, or for turning mechanics and their wives into hog-pens. The lower class fares are chiefly for emigrants and negroes, and they go down low enough in all conscience. A great quantity of traffic is carried at 0"50d., 0'48d., 0"40d., and even at 0'37d. Here are rates for the consideration of traffic committees, though perhat~s gentlemen who hold their hundred thousand pound stock in one line may not believe that there are persons among their fellow countrymen to whom a few shillings are as great an object as their guinea attendance fee is to them.
Let it not be imagined that the American lines are only short lines, having no scope for through traffic. They have short lines, it is tree, upon which generally the highest rates are charged; but they have lengths of line in comparison with which our London and North-Western route falls into the shade. The New York and Erie Railway, in its main line, from Piermont to Dunkirk, is 446 miles long, or nearly as far as from London to Perth. The lowest fare from London to Perth, 452 miles, is 30s., and this is likewise the lowest fare to Edinburgh and Glasgow, 405 miles. The third class fare on the New York and Erie Railway is 15s., or half that amount. The first class fare is 37S. , or little more than that amount, so that wealthy and working classes are equally well treated. The first class London and North-Western to Perth is 79s. 6d., and the express 87s. The New York and Erie ordinary rate, including stoppages, is '21 miles; what the London and North-Western is for third class passengers to Perth, we cannot make out; that for first and second class passengers seems to be about 2"2 miles per hour. The New York and Erie express rate is 27 miles, including stoppages, and the fare only first class fare. The London and North-Western rates to Perth are 26 miles and 30 miles per hour, the fair as above given; therefore, we have not much to boast of in the way of accommodation. It is not to be wondered at if" the average mileage o[ a New York passenger is twice that of an English passenger.
A peculiarity on some of the American lines is, that they charge higher rates [or intermediate, or, as they call them, way passengers. 'l'}~is is on account of the greater average mileage.
By MR. WJLLrA~r C. Crania, of Newpmt.* In order to explain the difiicnlties which have been contended with and surmounted by the use of these springs, the condition of' tile roads upon which they have produced such satisfactory results has to be notice(l, and the causes which first led to the introduction of india rubber as a substitute for steel, in bearing springs, buffers, and draw springs. The Western Valleys Lines of' the Monmouthshire Railway and Canal Company (upon which the writer is locomotive superintendent), consist of twenty-five miles of tramway, exclusive of branches, and worked by heavy coupled engines of the most improved construction. The tramplate is laid by means of chairs upon transverse sleepers, about 3 fleet apart, and an intermediate sleeper at the joints. This plate, although heavy (about 73 lbs. per yard), is of very weak section, and there is, consequently, considerable deflexion in it, a tendency to rise at the joints, and for the sleepers to work loose: the effect of this is, to cause a much greater expenditure of power necessary to overcome a series of rising and ihtling gradients, than would be the case upon an edge rail; and an undulatory motion of the engine is caused, which is extremely destructive to the steel springs hitherto in use on this line. The curves are unusually sharp, (some being under five chains radius, and the majority under twenty chains,) which is productive of a prejudicial ef[~et on the wheels, butlbrs, and other parts of the engines, carriages, and wagons. The gradients are very heavy, (some being 1 in 54,) producing a much greater strain on the draw-bars and couplings than is to be met with upon m'dinarv railways.
Upon such a road, the inconveniences attending the use of steel springs were both numerous and fbrmidable. In addition to the continual repairs which were required by the springs themselves, the injury done to the permanent way, arising fi'om the unequal aeticm of the spring, and the violent concussions they were subject to, when they were totally disabled (as was fl'equen@ the case), was large in amount, and of eonlinual occurrence, and of a character that involved considerable expense in repairs. Some idea of the damage thus occasioned may be formed, from the fi~et of the wheels tyres requiring to be replaced at least every eight months, having become worn by that time into a series of flats, mm'e nearly resemblingan irregular polygon in outline than the circumference of a circle.
The engine lyres used on the tramways are steeled on the wearing surface. With regard to the springs themselves, it may be proper to mention here, that the item of expenditure for steel springs (including wages for ' * From the London Repertory of Patent Inventions, July, 1853.