Journal - Franklin Institute of the State of Pennsylvania
Franklin Institute, Philadelphia | Franklin Institute (Philadelphia, Pa.)
~o7. \wp^ ~!T 177 Z9 ^SJ -n\ ri I I. \ S>r \ SS S9- pf 6 s e o i u o Cm O •3 a %i !=! O o > u a> o d Ha CD 2 D_ C i-ij/ i"(?/ <5"#-S^ ^ Of ^i- TT T^~^\9T 6» ^ rg ^TW f- VI TZ ItT /i9/ "r/" s■o^ 6 OP ! fA" -rp—^TT ITT ^M TW ?//• "F^ "TFT TUT i — i"// f-gf- ?€h 9fr;- /■Pf- fflf- ff^ Ot'^ "^s ■Cs ^ ^ <^, Lanza — Demonstration of Lames Formula. 329 DEMONSTRATION OF LAME'S FORMULA FOR THE STRENGTH OF THICK HOLLOW CYLINDERS SUBJECTED TO UNIFORM NORMAL PRESSURE. By Gaetaxo Lanza, Prof. Mass. Institute of Technology. The widely differing results obtained by the use of the various formulae for the thickness of the walls of hydrostatic presses (thick hollow cylinders) seem to render it desirable that in the case of a formula which is as reliable as Lamp's*, a demonstration should be given which could be read by a person who has not previously studied the theory of elasticity. This I have endeavored to do in the following article, the steps followed being virtually those taken by Lame, but all matter foreign to the subject in hand being eliminated. In this paper the word strain is used to indicate the elongation or shortening of a body per unit of length: the force producing it being indicated by the word stress. I = Let 0.4 = i^= inside radius ; 0-5 = 7?! = out- side radius ; let the length of the portion of the cylinder under consideration be unity ; let P = intensity of internal normal pressure ; P^ = intensity of external normal pressure. Assume any ring ^ Pe/ where OJE = ry 0 e = r -\- d r; p^ intensity of normal stress on the inside; p -\- d p ^ intensity of normal stress = intensity of tangential stress. Suppose that after the pressure is applied the ring E Fefhecomes E^F^e^f^ where OF^ = r-ru; 0 ei = r+u-^dr-]-du{u being a small quantity). I. As to the strains in the radial and in the tangential direction. In the radial direction the width F e = d r has become : du F, e, ^ d r 4- d u : hence the strain in this direction = -r-. 1 ^ ' a r In the tangential direction the length 2 t: r of the circumference ^ P has become : on the outside ; t 2 TT (r + u) ; hence strain in the tangential direction 2 r: Le9ons sur Elasticity des Corps Solide?,"" pai' M. G. Lame. 330 Qivil and Mechanical Engineering. II. To determine the relation between p, t, and r consistent with equilibrium. Consider the forces acting on the upper half ring E^Fye^fy', 1st, upward force due to internal pressure : = 2^ (r +«) * ; 2d, downward force due to external pressure : = 2 (j3 + dp) (r -f M + dr-\- du) ; 3d, tangential stress (represented as acting upward) : = 2t(dr -^du). (In the ordinary case when there is no external pressure on the cylinder, c^p and p have contrary signs, and 2, t {d r -\- d v) is a downward force and consequently a hoop tension) ; hence for equi- librium we must have : 1{p-^dp){r-^u-^dr-\-du) — 2'p{r-\-u) — 'lt[dr + du)=o, or 2pr + 2 j?i*4- 2p dr-\- 2pdu-{-2rdp-{-2u dp-\-2 d p dr-[- 2 dp du — 2pr — 2pu — 2t dr — 2t d u = o. Cancelling 2 p r and 2pu with — 2pr and — 2pu and omitting those terms that contain infinitesimals of a higher order than the first, viz.: 2p du,2u dp, 2 dp dr,2dp du,2t c? m, and dividing by 2, we obtain : p dr .-\- r dp — t dr ^= o. Dividing by d r, we have -7- + ^ 0 as the desired relation. o ^ ' dr r III. It is evident that the stresses p and t must depend upon, and du 1^1 therefore be, functions of the strains ^j- and — ; and moreover these d r r . du functions must be of such a nature as to vanish whenever both -7— d r u and — vanish, since we know that when there are no strains there r are no stresses ; hence if we express the stresses p and t in series du u of ascending powers and products of ~^^ and — , the development du u ■ must not contain any term independent both of 3— and —. a r r * The total upward force acting on the ring in consequence of the internal normal pressure will be the same as that acting on a section of the cylinder, made by a plane passing through its axis and the diameter Ey Fy . The area of this section will be 2 (r + w) X 1 = 2 (»■ + m), hence the total upward force will be 2 (r -[- «) X Pt or Lanza — Demonstration of Lame's Formula. 331 Moreover since ^ and — are themselves small quantities, we may d r r ^ omit all powers higher than the first, and all products of these strains, and use as a sufficiently close approximation only those terms con- taining their first powers ; hence we may write where p and t are (as has been stated) the intensities of a pair of stresses at right angles to each other at any point of the ring Now if the properties of the metal are independent of direction, i. e., if the elasticity is the same in all directions; we ought, by du u interchanging coordinates and hence by interchanging -r- and — to deduce either of the above equations from the other : hence we must /u\ /du\ have p = <2fi {-)+/5i (■;t-). This can only be when c:^ = ^ and ^^ = a; hence we have : /du\ „/M\ , ^ fdu\ f u\ P-"\dr) + "(7) »"'"='' U)+'^W' where a and /?, in the case of a homogeneous body whose elasticity is constant in all directions, are constant quantities depending on the properties of the material. From all the preceding we have the following three equations : dp p — t dr r du ^ u ■' d r r ^ du /u\ ' = '' <J7- + « (;■) ■ • d 10 Difierentiate (2) and we have ~- =a Subtract (8) from (2) and we have : (du u\ ^ (du u\ (du u\ d u Substitute these values of — ^ and p — t m (1) and we have : d r d^ u ^ du /9w a du au ^ du (^u ^Jr^'^V dr 7-'^7 dr~ ^~Vdr ~^1^^ ^' •. (1) . (2) (3) d^u ^ du ^ u r d r r^ 332 Civil and Mechanical Engineering. ^ du ^w 1^ du Bu Oancellmg ^ and — -^ with — — — and -ir respectively, ° r dr r- r dr r- ^ "^ and dividing by a we obtain : d^u 1 d u u dr' r dr r^ -p. .. , d^u /I du u \ By transposition we have : ^n. = — ( — ^ o \ •^ ^ dr^ \r dr r^ )', \ du u , . u but — ~T~ — -, is the differential coefficient of — with regard r dr r r \ r / . d^ u \ r / to r, or to — - — ; hence dr ' ^' dr" dr d (t) /d^ u r ^ r ^ -— -^ dr = — I ——. dr\ or performing the integration we du u have ,— = — — + 2 a (2 a beino; a constant whose value is dr r ^ ° not yet determined). Multiplying by r and transposing we obtain : du r -rr- -}- u='2 ar : dr d u but r , — + u is the differential coefficient of r u with regard to r or dr * d{ru) to — ; — ; hence we have : dr —z — =2ar; multiplying hj dr and integrating — dr = 2 a i r dr,ov r u = ar'^ -\- b [b being an- b other undetermined constant). .*. u = ar -\ , and from this equation we obtain directly the two strains, viz.: du b u b —^- ^a — ^ and — = a + — „. dr r~ r r Substituting these in the values of p and t we have : p = c;^a— ^) +/?(« + -^)=«(^<r + /9)— -^(cf — ^) Lanza — Demonstration of Lames Formula. 333 Next we proceed to determine the values of a and h, and to do this we must observe that when 7*= i2, or when the thin ring is taken as the ring whose radius is 0 A, we have ^ = — P (the minus sign being used because it is a compressive force), and when r = Mi, we have Making these substitutions we obtain : «(«f + /9)— ^, (^ — ,9) = — P; a(^ + ^9) — -^-, (^_^)=_p^; two equations of the first degree from which to determine a and h; any method of elimination will give us: 1 fPR^-p,R;-. 1 ({p-p,)r^r;-^ ^-a + ^\ R,'-R' j^^""^^- a-[A R,' — R' )' Substituting these values of a and b in the last value of t we have- PR'—P,R,' 2. JP—Pi) R' ^i ^~ R,^ — R^ + V R,^ — R^ ' which is the intensity of the hoop tension in the ring LJ^ F^ e^f^. The greatest value of t, or the greatest hoop tension evidently occurs in the inside ring, or when r = R, when the maximum value of t becomes: _ PIV — P,R,' {P—P,)R,' _ PR'—P,R,'-\-PR,'—P^R2 ~ R;' — R^ + R{ — R' ~ R^^ — R^ ' and the greatest intensity of hoop tension : P{R'' + r,^) — 2P^r;' ~ R,^ — R' If the intensity of the working strength of the material be k, we must therefore have, in order to ensure safety : P [R' + Ri) — 2 Pi R^^ R,' — R' ' or, clearing fractions, we have : k R,' — k R' = PR' + PR,^ — 2 Pi P/. transposing and factoring : B.^k — P-i- 2P,) = R^k+P); dividing by ^ — P + 2 Pj we have : E' ^^±^^R^ Extracting the square root P,=P ^L ~ =-, which determines ^ k — P + 2 Pj the external radius when the internal radius, the outside and inside pressures, and the working strength of the material are known. In the more common case when there is no external pressure, as in the 834 Civil and Mechanical Engineering. case of the hydrostatic press, when the pressure of the external air is left out of account, P^ is to be made equal to zero, and the above formulae become : Intensity of maximum hoop tension : = p(-^l + ^'andi?, = i?J^±Z. Hence, if in the case of a thick hollow cylinder, we have P = intensity of internal normal pressure ; Pj = intensity of external normal pres- sure ; ^ = inside radius of cylinder; M^ = outside radius of cylinder, and k intensity of working strength of the material ; or, which is the same thing, = intensity of maximum hoop tension consistent with safety, we shall have : 1st, Suppose P, Pj, k and R are known, and jRi required : -^L when there is an external pressure, k — P-\-2P, ^ I k -{- P Pi= P \ — ~ — when there is no external pressure. ' \ k—P ^ 2d, Suppose with the same data that the thickness of the walls be required, we shall have : Thickness when there is an external pressure : = P.-i? = p{^_i k-i-P P+2P, Thickness when there is no external pressure : \ \ k—P 3d, Suppose R, R^ and k to be known, and it be required to determine the greatest internal normal pressure that can be safely used, and we shall have : Intensity of greatest pressure = P = k '^\'~r^2- Ky -j- R' 4th, If R, Pj, P and P, be given, and it be required to determine the actual intensity of the greatest hoop tension, we shall have : Intensity of greatest hoop tension, when there is an external pressure : Rf—R' Intensity of greatest hoop tension when there is no external pressure : Gas Works Engineeririg. 335 GAS WORKS ENGINEERING. By Robert Briggs, C. E. [Continued from Vol. cii, page 272.] " There were two sets of purifiers, twenty feet by twenty- four feet on the floor, by five feet deep, having two-feet seals for the covers ; with a thirty-inch main pipe and twenty-four inch branch to and from each set of purifiers. The purifiers had a single layer screen, each with a bed of oxide preparation, twenty inches in depth. The prep- aration was said to be oxide of iron, iron-borings, charcoal, and I think lime. The beds of oxide preparation in the three purifiers gave but two inches of water column as the resistance pressure, as exhibited to me ; and the time of service of a bed, before it was fouled (for the full production of the works — about twenty-five thou- sand cubic feet per day, per set of purifiers), was said to be three to four days, or about eight millions cubic feet of gas would pass a set of purifiers before a bed would require revivification. " The reviving of the preparation was done in a yard and in an old deserted and open retort building adjacent to the purifying-house. The material was heaped as usual, for other oxide, one day, and gradually spread, to avoid the excessive heat which attends a more complete exposure to the air. " The odors attending this revivification were much less obvious than that accompanying the handling of foul lime at Philadelphia, although not so strong with ammonia as I have generally found at pure oxide heaps. They were using an '■enricJier' of ten per cent, of cannol coal to bring the gas up to sixteen candles quality, indica- ting a somewhat imperfect removal of carbonic acid. "It should be stated here, that good Westmoreland, or other American gas-coal, will yield, Avith careful charging of the coal into the retorts, quite four and one-half cubic feet of gas (of sixteen candles quality) to the pound of coal ; and if any coal, by weathering or otherwise, fails to give this quantity for the yield, it is customary to put in as a part of the charge, a portion of coal (like cannel) which will of itself alone be capable of giving gas of twenty-four to thirty candles quality; and this act is called ''enriching.' 336 Civil and Mechanical Engineering. " I next visited the Mutual Gas Works, Eleventh street and Ave- nue B, on the East river. At these works thej have in all ninety-five benches for coal-gas, with six retorts to each bench, and nine benches for naphtha-gas, also with six retorts to each bench. The retorts were 13" by 24" by 9'. The largest quantity of gas possible was made from the coal retorts — or a little over five cubic feet per pound on the average, for the year's work ; and this gas was then enriched by naphtha-gas of forty candles quality, to bring the whole gas de- livered from the holder up to twenty candle quality. " The usual work of the retort-house here, presented no subject for comment. The washer and condenser rooms might have been a par- lor for all the odor allowed to escape: the washing was done partly or wholly with ammonia water. There were two sets of purifiers, each twenty feet by twenty-four feet on the floor, by three feet deep, with twenty inch seals. In these purifiers there is but one layer of an oxide preparation, twenty-eight inches in depth. "The preparation was a secret one, perhaps patented, and the gas was perfecty satisfactory for sulphur purification, the same prepared material had been in use over a year, and the purifiers required changing once a week or so. "An inspection of the revivifying floor was much more satisfactory to the nostrils than that previously made at the New York Gas Works, but a slight gas-effluvia was present — that is, such a smell as attends gas-lime as distinguished from the ammonia vapors of pure oxide of iron revivification. I came away from these works without a trace of odor in my hair or clothes ; while the result of two visits, of similar duration, at the Market street works, was, that at both times the odor brought away was persistent and obnoxious to an excessive degree, remaining attached to clothing for two or three days after- wards. " It is proper to say, that, as naphtha-gas is used for enriching, the gas of the Mutual Company is, in some measure, independent of the presence of non-luminants, since a little more of the naphtha-giis will overcome this cause of imperfection ; and, also, that the naphtha- gas is an experiment of yet undetermined result. Former attempts to supply mixed gases and ' car6M?-e^^(?(?(7a8 ' have terminated unfortu- nately, from troubles of distribution in the mains or services, or in burning, or by cost of production, or in some unhappy way, to most parties interested. Q-as Works Engineering. 337 " These examples will serve to show that some processes of oxide- of-iron purification are practiced in the United States, and that they are comparatively devoid of objectionahle smells. The managers of the two works here instanced, state that the cost of oxide-of-iron purification is much less than half that of lime purification. " In the quotations from my notes upon the use of oxide of iron for purification, allusion is only made to the avoidance of odor, and no definite description is given of the process of revivification and its products. To supply that want of completiveness of the notes, I will state, the material is removed from the discarded purifiers and wheeled in barrows to a covered floor, where it is first piled in a heap three to five feet in depth. So soon as it is exposed to the air, it commences to heat, and it is therefore banked at first, in order to give a surface exposure only. The heating is attended with a copious effusion of ammonia gas, with a trace of naphthaline odor, and a little steam from evaporation of moisture from the oxide, which is usually damp from condensation from the gas. The next day after making the heap, it will be sufiiciently cooled to be turned over into rows, and on the following day to be spread in a thin layer. If the floor is large enough to allow this spreading to form a layer of two to three inches thickness, no further turning over is requisite ; but the oxide must be raked once or twice on the third day, and if the layer be thin and the oxide manipulated at the proper time, it will have been revivified at the end of the third day. The effusion of ammonia occurs only when the oxide is turned over or disturbed, and is of short duration (a few minutes only) after the turning or spreading ceases. The principal chemical changes are substantially inodorous, " Some attempts have been made to revivify the oxide in the purifiers without moving it, by admission of air through suitable connections, but they have resulted in failure (I am told), in conse- quence of the great heat evolved when the pressure of air is sufficient to pass it through the bed of foul oxide. " It must be remarked, that the resistance of flow of gas through the purifiers is much greater for the general system of oxide purifi- cation than for lime purification ; but it has been shown that the requisite apparatus for impelling the gas already exists at the Market Street works, and the question of additional power needed to effect the purpose is really insignificant, as the movement of all the gas possible to be made at these works at any time, under Whole No. Vol. CII.— (Third Series, Vol.lxxii.) 24 338 Civil and Mechanical Engineering. eighteen inches of water-column pressure, will not exceed the per- formance of a ten horse-power engine. " The process of oxide-of-iron purification results in great saving of expense to the gas-maker. At the New York Gas Works it was asserted that the entire cost of purification did not exceed five- eighths of a cent per thousand cubic feet of gas made. It is un- questionable that the use of the oxide process would result in great profit to the Gas Trust from saving of labor and of crude material, and I believe would be highly advantageous to the consumers, in tbe improvement of the quality of gas made, the value of which would far more than recompense the cost of introducing the process. " There is yet another way to avoid the nuisance proceeding from dry-lime purification, which is exhibited at the works of the Manhat- tan Gas Company, visited by me on the 16th and 17th of March (inst.) The North River Station of the works of the Manhattan Gas Company of New York, is located on the blocks of ground west of Tenth Avenue, on West Eighteenth and Seventeenth Streets and adjacent streets. Omitting any general description of the works, only to say that the condensing and washing house was devoid of the least possible odor, I will proceed to a particular account of the system of ventilation of the foul-lime resulting from dry-lime purifi- cation, there in successful operation. At these works they have (for the one thousand and thirty-two retorts in the benches, eight hundred and forty — highest number in use at one time) three sets of purifiers, seventeen feet by twenty-two feet on the floor, by three and one-half feet deep, with seven layers of lime in each, and the usual connecting pipes of inlet and outlet. " Besides these usual pipe connections for gas, they have likewise connected to the bottom of each purifier, a sixteen-inch pipe with a suitable stop-valve ; these pipes join into a twenty-four inch main pipe, and the latter connects to an exhauster, in this instance a species of screw-fan, five feet in diameter. From the exhauster, a twenty-four inch pipe leads to a jet-washer, which corresponds in construction to that before described at Market Street works, only it is but one-fourth the length (that is, ten feet in lieu of forty feet on the floor), the height and width being about the same as the Phila- delphia washers. All this part of the apparatus is in close proximity to the purifying-house. From the washer, the pipe continues to a drain-pipe three feet high by two feet wide (egg shape), which leads G-as Works Eiigineering. 339 under the roadway of West Seventeenth Street, nearly one thousand feet, to a deodorizing building. This deodorizing building has two closed deodorizing-roows, with only a doorway for entrance, and on the floor of each room is a brick deodorizer-box, without cover. These boxes are thirty feet long by sixteen feet wide by three and one-half feet deep, and have seven layers, of similar construction to those used in usual dry-lime purifiers. Branches from the main drain- pipe, controlled by valves, open into the bottoms of the brick puri- fiers ; and openings, also controlled by valves, from the upper part of the rooms, lead to a chimney seventy feet high. The screens are covered with ventilated spent-lime, about one-tenth of all the lime being used at these secondary purifiers. The purpose of this appa- ratus is the ventilation of the foul lime in the purifiers, and it is effectual in this way ; — " When a purifier is ready to discharge, and is shut ofi" as usual from the gas works by the centre valve, the cover is lifted from the seat and suspended about one inch above the box. The valve of the ventilating pipe is opened and the ventilating exhauster started. " The wash water is brownish yellow, and not ofi"ensive ; it is run ofi" into the sewer. " Very unexpectedly, the long drain-pipe main was found to have acted as a condenser of naphthaline, whose presence in great quantity, in foul lime, has not been before noticed. The pipe was coated with naphthaline to the extent of jive or six inches after a year's use, and it was removed by introducing a jet of steam and blowing it through by means of the exhauster. [It would seem that naphthaline was soluble in steam or vapor of water, while it is nearly insoluble in water,] 340 Civil and Mechanical Engineering. " Having reached the secondary purifying-house, the foul air is passed through one of the rooms and discharged through the chimney into the open air. The deodorizing material in this case was stated to be spent-lime from the gas purifiers. It was found that pure lime had no efi"ect on the foul air, and at the suggestion of Mr. Carl H. Schultz, chemist. New York, the spent-lime was employed with great success. The lime on the deodorizing screens is revived in part, by forcing fresh air throught it for an hour, after the operation of ven- tilating a gas purifier has ceased. The lime is customarily changed in the deodorizing house, for every purifier changed in the purifying house. This operation'^is highly satisfactory to the Manhattan Com- pany, and answers to meet all the requirements of the New York Board of Health, which has forbidden the use of dry-lime purifica- tion at the gas works of that city. " [§§ Five.'] At the Market Street works, beside the manufacture of gas, there are two perpetual lime-kilns for the making of oyster- shell lime for use in the purifiers. This branch of the business is not carried on, to my present recollection, by any other gas works in this or in other countries. " The plant is a very simple one. A stone structure, about thirty feet long by sixteen feet broad and twenty-five to thirty feet high, contains two kilns or ' stacks,' internally cylinders of eight feet or so in diameter, with the lower part reduced to perhaps three feet ; square openings from one side permit access to the bottoms or hearths of the stacks. The base of the stacks is surrounded by temporary buildings or sheds. These stacks are situated between the purifying house and the Schuylkill river, and are about one hundred and fifty, or two hundred feet north of Chestnut Street Bridge ; between them and the bridge, the space of wharf is utilized, first by the foul-lime dump, and next, by a pile of generally twenty thousand to forty thousand bushels of oyster-shells (or more). " The operation of making lime in these stacks, is to charge at the top a quantity of oyster-shells, mixed with one-fourth the quantity of coke breize and fine coke dust ; and at certain regular intervals some bars of iron are driven in across the tops of the openings to the hearth, and the burned oyster-shells under the bars, now converted to lime, are drawn out ; when, removing the bars, the charge falls from bottom to top ; and after the stack has once been lighted, the process of burning will go on continuously with regularity. Gias Works Engineering. 341 " At first there arises and escapes from these kilns the steam from the moisture of the oyster-shells, laden vrith the odors of cooked oysters, mingled with those proceeding from decayed remains ; and after this, and accompanying it, escapes a volume of nearly pure carbonic acid ; together with a little chlorine vapor or gas, and some small quantity of other gases. This carbonic acid proceeds from the carbonate of lime of which the oyster-shells are mainly composed, and from the combustion of the coke, which disappears altogether during the process ; and as this gas, at the temperature of leaving the kiln, where the upper layer of oyster-shells and the moisture will have nearly taken up all the heat of burning the coke, which occurs at or below the middle of the stack, has about the same density as the external air, it follows that, although it may diffuse rapidly, yet it does not dissipate by ascension. I am informed by competent authority that the height of the approach of the Chestnut Street Bridge, in front of the heap of oyster-shells at the gas works, is thirty-one feet six inches above top of ground. Consequently, as the tops of these kilns are nearly at the same level as Chestnut Street Bridge (about two hundred feet distant to the southward), and of Market Street Bridge (about three hundred feet distant to the northward), any current of air up or down the river will sweep these gases and odors directly across them. " The oyster-shell heap, near Chestnut Street Bridge, emits dis- agreeable odors, and, speaking of it in the mildest terms, can be generally denominated as offensive to the public. I only state the existence of the heap to complete my narration of the arrangement and occupation of the grounds of the Market Street Station of the Philadelphia Gas Works. III. It cannot be said by any person practically acquainted with the manufacture and supply of gas, and competent to advise on the location of gas houses, that the Market Street works are judiciously situated as regards the main thoroughfares and streets of the city, although the place may give, at this time, great advantages for dis- tribution. The barn-yard and the pig-pen are necessary adjuncts to the farm dwelling, and the farmer is happy in their contemplation ; but if the county lays out a road behind the farmer's house, when his barn is outgrown he will be likely to build a new one in another place. 342 Civil and Mechanical Engineering. " It must be regarded as a grave error that the works were not removed, in place of having been reconstructed on a larger scale, a few years since. " The holders could have been and should have been preserved, and possibly additional ones erected, but after the entrance of the city was established by the erection of the passenger station of the Pennsylvania Railroad, and Market Street became the important avenue, some reasonable expenditure should have been incurred to- have removed the operation of making gas to some other part of the city. And this could have been done by the construction of a single five foot or six foot wrought-iron pipe main, at no enormous outlay, considering the importance of the object. " The Beckton Gas Works, of the Chartered Gas Company of London, which are situated nearly eight miles below the centre of distribution, and where there are two thousand one hundred and sixty double-ended retorts (equivalent to four thousand three hundred and twenty retorts of the Market Street size), can be taken as an example of the recognition of the comity of the public as weighed against the right to carry on objectionable manufactures in the midst of a city, no matter how necessary to the city itself such a manufacture may be. Any person will tolerate and endure in his shop, laboratory, manufactory or avocation, odors or dust more or less unhealthy and disagreeable, but no one will desire these inconveniences at his home. " IV. The time requisite to make the changes necessary to avoid the nuisances now proceeding from the Market street works can be stated as follows, taking up the various sources of complaint in order : — '''First. — The construction of a house and smoke-tower for quench- ing the coke can be eflfected the present season ; certainly before autumn sets in. — The economy of quenching and handling coke by shutes would probably defray the interest of cost of house, &c. ^^ Second. — The disuse of lime purification and the substitution of oxide of iron, as used at the works of the New York Gas Company or those of the New York Mutual, could be done at once, upon pro- curement of oxide or ' prepared material.' I think that this change could readily be effected within one week. The introduction of the English process of purification could be done by temporary pipe con- nections, so as to give the use of two sets of the purifiers within G-as Works Engineering. 343 two weeks' time ; and the construction of necessary additional puri- fiers for use of the three sets could be readily effected this present season. " The plea of delay in getting perforated screens at the Metropoli- tan Works (New York), stated to have been made by the officers of that company, as appears in the affidavit of Professor C. F. Chandler, was purely a dilatory one. I do not remember ever to have seen perforated screens used with oxide of iron, and slat screens, such as are used at the Philadelphia Gas Works, are those generally if not universally employed. "The construction of temporary sheds to cover the revivifying floor would take but a few days, and permanent structures of suitable character for the locality could easily be built this season. The profit to the gas company arising from the substitution of oxide of iron purification would probably be $4000 to $5000 per year at the Market street works alone. "Any desired amount of oxide of iron can be procured at a week's notice ; but two weeks' delay might arise in crushing or preparing it for the first start. " Third. — The introduction of the system for deodorizing foul lime now used in the Manhattan Company's Works in New York could be effected in six weeks' time, if any urgency existed ; or in twelve weeks' time, at leisure. ^'-Fourth. — The disuse of the lime-kilns, by the substitution of better lime for purification, could be effected at six days' notice, which would be the time requisite to commence the railroad deliveries of the quantities needed. The marble from which nearly pure lime can be made can be found in abundance within fifty miles of Philadelphia, where kilns now exist ready for burning it, A bushel of marble-lime is equal in weight and efficiency to two and one-fourth bushels of oyster-shell lime. '■^ Fifth. — The removal of the kilns to Point Breeze or elsewhere could be effected, if any urgency existed, in six weeks ; but at leisure perhaps thirteen or sixteen weeks would be required." 344 Civil and Mechanical Engineering. STREET AND TRAM LOCOMOTIVES, From The Practical Magazine, Loudon, Sept., 1876. In our number for June (page 176 of the present volume) we in- serted, from the Journal of the Franklin Institute, a few para- graphs concerning the use of steam carriages on street railways and common roads. At page 188 we gave a description and engraving of Messrs. Merryweather's steam tram-carriage, lately commenced working on the Paris tramways. It occurs to us that it may be use- ful to present here a few connecting links of- history, so as to prepare the general reader for a due comprehension of other novelties which are likely to make their appearance ere long. Railways, as we all know, have solved the problem of steam-power vs. horse-power, so far as regards the traction of heavy loads at high speed. It remains still to be ascertained whether this substitution ever can or will be so complete in regard to what may be called " omnibus traffic," distin- guished by lighter loads, lower speed, and more frequent stoppages. It becomes, on this account, interesting to glance at the inventions which, from time to time, have been brought forward, partly for steam-traction on tramways, but more generally for use on common roads. If we mention Sir Isaac Newton's name in connection with this subject, it is only in relation to a speculation which he made no attempt to put to a practical test. He suggested a globular vessel, placed on four small wheels, with a jet-pipe on one side and a driver's seat on the other. Steam, generated in the globe by a suitable fire, would issue from the tube and drive the little four-wheeler onward by reaction, on the principle of the rocket. Dr. Robinson, nearly a century later, communicated to James Watt an idea for the propul- sion of a carriage along common roads by steam. A cask of iron- bound staves for a boiler ; an iron furnace or fire-box, fed from above, immersed in the water in the cask ; steam from the heated water moving a piston in a cylinder, and the piston moving a small wheel- carriage on which the cask, &c., were placed, — such Avas the idea; but Watt carried it no further than the sketching of a few drawings. Of those who really advanced to the stage of an actual carriage, or at least a working model, one of the first was Cugnot, who made Street and Tram Locomotives. 345 a rude model, still preserved in one of the public museums of Paris, and then a carriage, which proved to be too energetic at its work, for it dashed through a brick wall and brought disfavor to its inven- tor. William Murdoch, about 1790, ran a steam carriage on the highway near Redruth, but the chief fact now known concerning it, is, that the Cornish miners rushed away in affright from " the fiery little monster running along the road without horses." William Symington, whose name is as favorably associated with the history of steam navigation as Murdoch's with that of gas-lighting, exhibited at Edinburgh a model of a steam carriage, the merits of which he was unable to test by reason of the wretched state of the roads. Oliver Evans, of Pennsylvania, proposed to the legislature of that state a scheme for steam traction on common roads ; his plan met with no response. He was greatly laughed at for prophesying that the day would come when such carriages would attain a speed of fifteen miles an hour. Who was nearer the truth, the derider or the derided ? Early in the present century we find Trevithick and Vivian com- pleting and running their steam carriage on the very spot where the Euston station now stands — not a bad association of ideas, it will be admitted. From the description published, it seems to have been a tolerably light and compact piece of mechanism. A carriage rested on four wheels, of which the front pair guided or steered, while the hinder part supported the greater part of the weight ; a boiler and a horizontal cylinder were placed at the back of the hind axle, while rods, tooth-wheels, cranks, &c., connected the piston of the cylinder with the wheels of the carriage. Nobody took up these schemes in earnest — war and political troubles occupied men's thoughts in other than peaceful pursuits. But a new spurt took place just about half a century ago. Mr. Grif- fiths employed Bramah to work out an idea of his, and to make im- provements in practical details. Little is now known of the steam carriage which resulted from this partnership in ingenuity, except that there were two cylinders with pistons, a tubular boiler, and ver- tical springs to deaden the concussion. Another inventor, David Oordon, had firmly persuaded himself that no locomotive carriage, or steam engine on wheels, can travel up an incline. He therefore devised a strange monster, with six jointed levers to act like six legs, with bending movements to imitate those of knees and insteps, the legs alternately stepping and dangling ! Another mode of overcom- 346 Civil and Mechanical Engineering. ing the supposed difficulty was by putting a steam engine inside a large iron drum, making the engine roll the drum as a squirrel rolls his cage, and a carriage to roll on after the drum. When it was proved that a locomotive can travel up hill, if not steep, inventors took courage, and novelties appeared in rapid suc- cession. Goldsworthy Gurney built a steam carriage which Sir Charles Dance " tooled " (as coaching men would call it) between Gloucester and Cheltenham. It ran to and fro four times a day, doing the distance of nine miles in about an hour. All kinds of obstacles were thrown in his way. Innkeepers, hostlers, horse-dealers, coach- makers, road trustees, interposed impediments wherever possible. Gurney and Dance were beaten ; but nevertheless they obtained a favorable report from a committee of the House of Commons. The committee fairly judging the evidence brought before them, reported that the steam carriage could maintain an average speed of ten miles an hour ; that it would carry twelve or fourteen passengers ; that the total weight of carriage, machinery, fuel, water, passengers, drive?, and attendant, might be under three tons ; that the carriage, with such a load, would ascend and descend ordinary roads with fa- cility ; and that the broad wheels were less likely to cut up the roads than the narrow wheels and horses' feet of ordinary road vehicles. Whether the system would eventually be cheaper than horse-traction could not be determined on so short an experience. Captain Ogle was another experimenter in the same line. He made a great sensation by running a new steam carriage from Oxford to Birmingham, ten miles an hour in the towns, and twelve miles in the more open country. His contrivance was a kind of mail coach for six inside passengers and eight outside, the motive power being placed in the rear of the passenger compartment. Rivals appeared in this district and in that, but all went into oblivion after a brief period of excitement. Mr. Hancock's "infant" steam coach plied for a time to and fro between London and Stratford. A steam coach under the command of Colonel Macerone, in like manner had its little day. Mr. Scott Russell (perhaps the only distinguished living representa- tive of that group of inventors) constructed a steam carriage which plied for a time between Glasgow and Paisley. Burstall (a name that might be regarded as rather ominous in connection with such subjects), with his partner Hill, Summers and Ogle, Dance and Field, James, Heaton, Church, Squire, Hills, Sir James Anderson — all are Street and Tram Locomotives. 347 to be included among the inventors which turned their attention to these matters at various periods from half a century to a quarter of a century ago. Why they all failed we need not wait to say. Some of the engines were too heavy ; some had difficulty in maintaining their water-feed ; some did not steer readily nor stop with sufficient promptness ; some frightened the horses with their noise ; while others were placed beyond the reach of profit by inordinate tolls im- posed by turnpike trusts. There is still no paucity of invention of steam coaches, if the smallest encouragement be offered them. The Earl of Caithness created quite a lively sensation in Scotland a few years ago, by per- forming a journey which certainly was unequaled of its kind. A very ingenious steam carriage was invented by Mr. Rickett, It was a kind of hooded chaise, with a small steam engine behind it, occu- pying about as much space altogether as a horse and chaise ; the chaise had a seat for three persons, while the engine was attended to by a fourth person, stationed in the rear. A supply of coal for fifty miles and of water for fifteen could be carried ; when thus supplied, the whole affair, with four persons, weighed about a ton and a half. 