Kitabı oku: «A History of Inventions, Discoveries, and Origins, Volume II (of 2)»

THE STEAM-ENGINE,
AND THE DISCOVERIES OF JAMES WATT

Although the plan of this new edition of Beckmann’s ‘History of Inventions and Discoveries’ was to confine it to the subjects treated of in the original work, yet we feel it imperative to make an exception in favour of the Steam-Engine, the most important of all modern inventions.

The power of steam was not entirely unknown to the ancients, but before the æra rendered memorable by the discoveries of James Watt, the steam-engine, which has since become the object of such universal interest, was a machine of extremely limited power, inferior in importance and usefulness to most other mechanical agents used as prime movers. Hero of Alexandria, who lived about 120 years before the birth of Christ, has left us the description of a machine, in which a continued rotatory motion was imparted to an axis by a blast of steam issuing from lateral orifices in arms placed at right angles to it. About the beginning of the seventeenth century, a French engineer, De Caus, invented a machine by which a column of water might be raised by the pressure of steam confined in the vessel, above the water to be elevated; and in 1629, Branca, an Italian philosopher, contrived a plan of working several mills by a blast of steam against the vanes; from the descriptions, however, which have been left us of these contrivances, it does not appear that their projectors were acquainted with those physical properties of elasticity and condensation on which the power of steam as a mechanical agent depends.

In 1663, the celebrated Marquis of Worcester described in his Century of Inventions, an apparatus for raising water by the expansive force of steam only. From this work we extract the following short account of the first steam-engine. “68. An admirable and most forcible way to drive up water by fire; not by drawing or sucking it upwards, for that must be as the philosopher calleth it, intra sphæram activitatis, which is but at such a distance. But this way hath no bounder, if the vessel be strong enough: for I have taken a piece of whole cannon, whereof the end was burst, and filled it three-quarters full of water, stopping and screwing up the broken end as also the touch-hole; and making a constant fire under it, within twenty-four hours it burst and made a great crack; so that having a way to make my vessels so that they are strengthened by the force within them, and the one to fill after the other, I have seen the water run like a constant stream, forty feet high: one vessel of water rarefied by fire, driveth up forty of cold water; and a man that tends the work is but to turn two cocks, that one vessel of water being consumed, another begins to force and refill with cold water, and so successively; the fire being tended and kept constant, which the self-same person may likewise abundantly perform in the interim, between the necessity of turning the said cocks.”

The next name to be mentioned in connection with the progressive history of the invention of the steam-engine, is that of Denis Papin, a native of France, who, being banished from his country, was established Professor of Mathematics at the University of Marburg, by the Landgrave of Hesse. He first conceived the important idea of obtaining a moving power by means of a piston working in a cylinder (1688), and subsequently (1690) that of producing a vacuum in the cylinder by the sudden condensation of steam by cold. In accordance with these ideas he constructed a model consisting of a small cylinder, in which was inserted a solid piston, and beneath this a small quantity of water; on applying heat to the bottom of the cylinder, steam was generated, the elastic force of which raised the piston; the cylinder was then cooled by removing the fire, when the steam condensed and became again converted into water, thus creating a vacuum in the cylinder, into which the piston was forced by the pressure of the atmosphere; there is, however, no evidence of his having carried that or any other machine into practical use, before machines worked by steam had been constructed elsewhere.

The first actual working steam-engine of which there is any record, was invented by Captain Savery an Englishman, to whom a patent was granted in 1698 for a steam-engine to be applied to the raising of water, &c. This gentleman produced a working-model before the Royal Society, as appears from the following extract from their Transactions: – “June 14th, 1699. Mr. Savery entertained the Royal Society with showing a small model of his engine for raising water by help of fire, which he set to work before them: the experiment succeeded according to expectation, and to their satisfaction.” This engine, which was used for some time to a considerable extent for raising water from mines, consisted of a strong iron vessel shaped like an egg, with a tube or pipe at the bottom, which descended to the place from which the water was to be drawn, and another at the top, which ascended to the place to which it was to be elevated. This oval vessel was filled with steam supplied from a boiler, by which the atmospheric air was first blown out of it. When the air was thus expelled, and nothing but pure steam left in the vessel, the communication with the boiler was cut off, and cold water poured on the external surface. The steam within was thus condensed and a vacuum produced, and the water drawn up from below in the usual way by suction. The oval steam-vessel was thus filled with water; a cock placed at the bottom of the lower pipe was then closed, and steam was introduced from the boiler into the oval vessel above the surface of the water. This steam being of high pressure, forced the water up the ascending tube, from the top of which it was discharged; and the oval vessel being thus refilled with steam, the vacuum was again produced by condensation, and the same process was repeated by using two oval steam-vessels, which would act alternately; one drawing water from below, while the other was forcing it upwards, by which an uninterrupted discharge of water was produced. Owing to the danger of explosion, from the high pressure of the steam which was used, and from the enormous waste of heat by unnecessary condensation, these engines soon fell into disuse.

Several ingenious men now turned their attention to the improvement of the steam-engine, with a view to reduce the consumption of fuel, which was found to be so immense as to preclude its use except under very favourable circumstances; and in 1705, Thomas Newcomen, a blacksmith or ironmonger, and John Cawley, a plumber and glazier, patented their atmospheric engine, in which at first condensation was effected by the affusion of cold water upon the external surface of the cylinder, which was introduced into a hollow casing by which it was surrounded. Having accidentally observed that an engine worked several strokes with unusual rapidity without the supply of condensing water, Newcomen found, on examining the piston, a hole in it through which the water poured on to keep it air-tight issued in the form of a little jet, and instantly condensed the steam under it; this led him to abandon the casing and to introduce a pipe furnished with a cock, into the bottom of the cylinder, by which water was supplied from a reservoir. Newcomen’s engine required the constant attendance of some person to open and shut the regulating and condensing valves, a duty which was usually entrusted to boys, called cock-boys. It is said that one of these boys, named Humphrey Potter, wishing to join his comrades at play, without exposing himself to the consequences of suspending the performance of the engine, contrived by attaching strings of proper length to the levers which governed the two cocks, to connect them with the beam, so that it should open and close the cocks as it moved up and down, with the most perfect regularity. By this simple contrivance the steam-engine for the first time became an automaton.

It was in repairing a working model of a steam-engine on Newcomen’s principle for the lectures of the professor of natural philosophy at the University of Glasgow, that James Watt directed his mind to the prosecution of those inventions and beautiful contrivances, by which he gave to senseless matter an almost instinctive power of self-adjustment, with precision of action more than belongs to any animated being, and which have rendered his name celebrated over the world.

At the time of which we speak, Newcomen’s engine was of the last and most approved construction. The moving power was the weight of the air pressing on the upper surface of a piston working in a cylinder; steam being employed at the termination of each downward stroke to raise the piston with its load of air up again, and then to form a vacuum by its condensation when cooled by a jet of cold water, which was thrown into the cylinder when the admission of steam was stopped. Upon repairing the model, Watt was struck by the incapability of the boiler to produce a sufficient supply of steam, though it was larger in proportion to the cylinder than was usual in working engines. This arose from the nature of the cylinder, which being made of brass, a better conductor of heat than cast-iron, and presenting, in consequence of its small size, a much larger surface in proportion to its solid content than the cylinders of working engines, necessarily cooled faster between the strokes, and therefore at every fresh admission consumed a greater proportionate quantity of steam. But being made aware of a much greater consumption of steam than he had imagined, he was not satisfied without a thorough inquiry into the cause. With this view he made experiments upon the merits of boilers of different constructions; on the effect of substituting a less perfect conductor, as wood, for the material of the cylinder; on the quantity of coal required to evaporate a given quantity of water; on the degree of expansion of water in the form of steam: and he constructed a boiler which showed the quantity of water evaporated in a given time, and thus enabled him to calculate the quantity of steam consumed at each stroke of the engine. This proved to be several times the content of the cylinder. He soon discovered that, whatever the size and construction of the cylinder, an admission of hot steam into it must necessarily be attended with very great waste, if in condensing the steam previously admitted, that vessel had been cooled down sufficiently to produce a vacuum at all approaching to a perfect one. If, on the other hand, to prevent this waste, he cooled it less thoroughly, a considerable quantity of steam remained uncondensed within, and by its resistance weakened the power of the descending stroke. These considerations pointed out a vital defect in Newcomen’s engine; involving either a loss of steam, and consequent waste of fuel; or a loss of power from the piston’s descending at every stroke through a very imperfect vacuum.

It soon occurred to Watt, that if the condensation were performed in a separate vessel, one great evil, the cooling of the cylinder, and the consequent waste of steam, would be avoided. The idea once started, he soon verified it by experiment. By means of an arrangement of cocks, a communication was opened between the cylinder, and a distinct vessel exhausted of its air, at the moment when the former was filled with steam. The vapour of course rushed to fill up the vacuum, and was there condensed by the application of external cold, or by a jet of water; so that fresh steam being continually drawn off from the cylinder to supply the vacuum continually created, the density of that which remained might be reduced within any assignable limits. This was the great and fundamental improvement.

Still, however, there was a radical defect in the atmospheric engine, inasmuch as the air being admitted into the cylinder at every stroke, a great deal of heat was abstracted, and a proportionate quantity of steam wasted. To remedy this, Watt excluded the air from the cylinder altogether; and recurred to the original plan of making steam the moving power of the engine, not a mere agent to produce a vacuum. In removing the difficulties of construction which beset this new plan, he displayed great ingenuity and powers of resource. On the old plan, if the cylinder was not bored quite true, or the piston not accurately fitted, a little water poured upon the top rendered it perfectly air-tight, and the leakage into the cylinder was of little consequence, so long as the injection water was thrown into that vessel. But on the new plan, no water could possibly be admitted within the cylinder; and it was necessary, not merely that the piston should be air-tight, but that it should work through an air-tight collar, that no portion of the steam admitted above it might escape. This he accomplished by packing the piston and the stuffing-box, as it is called, through which the piston-rod works, with hemp. A further improvement consisted in equalising the motion of the engine by admitting the steam alternately above and below the piston, by which the power is doubled in the same space, and with the same strength of material. The vacuum of the condenser was perfected by adding a powerful pump, which at once drew off the condensed and injected water, and with it any portion of air which might find admission; as this would interfere with the action of the engine if allowed to accumulate. His last great change was to cut off the communication between the cylinder and the boiler, when a portion only, as one-third or one-half, of the stroke was performed; leaving it to the expansive power of the steam to complete it. By this, œconomy of steam was obtained, together with the power of varying the effort of the engine according to the work which it has to do, by admitting the steam through a greater or smaller portion of the stroke.

These are the chief improvements which Watt effected at different periods of his life. He was born June 19, 1736, at Greenock, where he received the rudiments of his education. Having at an early age manifested a partiality for the practical part of mechanics, he went in his eighteenth year to London to obtain instruction in the profession of a mathematical instrument-maker, but remained there little more than a year, being compelled to return home on account of his health. In 1757, shortly after his return home, he was appointed instrument-maker to the University of Glasgow, and accommodated with premises within the precincts of that learned body. In 1763 he removed into the town of Glasgow, intending to practise as a civil engineer. His first patent is dated June 5, 1769, which parliament extended in 1775 for twenty-five years in consideration of the national importance of the inventions, and the difficulty and expense of introducing them to public notice. He died at his house at Heathfield in the county of Stafford, on the 25th of August, 1819, at the advanced age of eighty-four, after having realized an ample fortune, the well-earned reward of his industry and ability.

To enter into the history of the various applications of the steam-engine to the different branches of industry would carry us beyond the bounds of this work. “To enumerate its present effects,” says a well-known writer on the steam-engine¹, “would be to count almost every comfort and every luxury of life. It has increased the sum of human happiness, not only by calling new pleasures into existence, but by so cheapening former enjoyments as to render them attainable by those who before could never have hoped to share them: the surface of the land, and the face of the waters are traversed with equal facility by its power; and by thus stimulating and facilitating the intercourse of nation with nation, and the commerce of people with people, it has knit together remote countries by bonds of amity not likely to be broken. Streams of knowledge and information are kept flowing between distant centres of population, those more advanced diffusing civilization and improvement among those that are more backward. The press itself, to which mankind owes in so large a degree the rapidity of their improvement in modern times, has had its power and influence increased in a manifold ratio by its union with the steam-engine. It is thus that literature is cheapened, and by being cheapened, diffused; it is thus that reason has taken the place of force, and the pen has superseded the sword; it is thus that war has almost ceased upon the earth, and that the differences which inevitably arise between people and people are for the most part adjusted by peaceful negotiation.”

LENDING AND PAWNBROKING

It appears singular to us at present that it should have been once considered unlawful to receive interest for lent money; but this circumstance will excite no wonder when the reason of it is fully explained. The different occupations by which one can maintain a family without robbery and without war, were at early periods neither so numerous nor so productive as in modern times; those who borrowed money required it only for immediate use, to relieve their necessities or to procure the conveniences of life; and those who advanced it to such indigent persons did so either through benevolence or friendship. The case now is widely different. With the assistance of borrowed money people enter into business, and carry on trades, from which by their abilities, diligence, or good fortune, so much profit arises that they soon acquire more than is requisite for their daily support; and under these circumstances the lender may undoubtedly receive for the beneficial use of his money a certain remuneration, especially as he himself might have employed it to advantage; and as by lending it he runs the risk of losing either the whole or a part of his capital, or at least of not receiving it again so soon as he may have occasion for it.

Lending on interest, therefore, must have become more usual in proportion as trade, manufactures, and the arts were extended; or as the art of acquiring money by money became more common: but it long continued to be detested, because the ancient abhorrence against it was by an improper construction of the Mosaic law converted into a religious prejudice², which, like many other prejudices more pernicious, was strengthened and confirmed by severe papal laws. The people, however, who often devise means to render the faults of their legislators less hurtful, concealed this practice by various inventions, so that neither the borrower nor lender could be punished, nor the giving and receiving of interest be prevented. As it was of more benefit than prejudice to trade, the impolicy of the prohibition became always more apparent; it was known that the new-invented usurious arts under which it was privately followed would occasion greater evils than those which had been apprehended from lending on interest publicly; it was perceived also that the Jews, who were not affected by papal maledictions, foreigners, and a few natives who had neither religion nor conscience, and whom the church wished least of all to favour, were those principally enriched by it.

In no place was this inconvenience more felt than at the Romish court, even at a time when it boasted of divine infallibility; and nowhere was more care employed to remove it. A plan, therefore, was at length devised, by which the evil, as was supposed, would be banished. A capital was collected from which money was to be lent to the poor for a certain period on pledges without interest. This idea was indeed not new; for such establishments had long before been formed and supported by humane princes. The emperor Augustus, we are told, converted into a fund the surplus of the money which arose to the State from the confiscated property of criminals, and lent sums from it, without interest, to those who could pledge effects equal to double the amount³. Tiberius also advanced a large capital, from which those were supplied with money for three years, who could give security on lands equivalent to twice the value⁴. Alexander Severus reduced the interest of money by lending it at a low rate, and advancing sums to the poor without interest to purchase lands, and agreeing to receive payment from the produce of them⁵.

These examples of the ancients were followed in modern Italy. In order to collect money, the popes conferred upon those who would contribute towards that object a great many fictitious advantages, which at any rate cost them nothing. By bulls and holy water they dispensed indulgences and eternal salvation; they permitted burthensome vows to be converted into donations to lending-houses; and authorised the rich who advanced them considerable sums to legitimate such of their children as were not born in wedlock. As an establishment of this kind required a great many servants, they endeavoured to procure these also on the same conditions; and they offered, besides the above-mentioned benefits, a great many others not worth notice, to those who would engage to discharge gratis the business of their new undertaking; but in cases of necessity they were to receive a moderate salary from the funds. This money was lent without interest for a certain time to the poor only, provided they could deposit proper pledges of sufficient value.

It was, however, soon observed that an establishment of this kind could neither be of extensive use nor of long duration. In order to prevent the secret lending of money, by the usurious arts which had begun to be practised, it was necessary that it should advance sums not only to those who were poor in the strictest sense of the word, but to those also who, to secure themselves from poverty, wished to undertake and carry on useful employments, and who for that purpose had need of capitals. However powerful the attractions might be, which, on account of the religious folly that then prevailed, induced people to make large contributions, they gradually lost their force, and the latter were lessened in proportion, especially as a spirit of reformation began soon after to break out in Germany, and to spread more and more into other countries. Even if a lending-house should not be exhausted by the maintenance of its servants, and various accidents that could not be guarded against, it was still necessary, at any rate, to borrow as much money at interest as might be sufficient to support the establishment. As it was impossible that it could relieve all the poor, the only method to be pursued was to prevent their increase, by encouraging trade, and by supplying those with money who wanted only a little to enable them to gain more, and who were in a condition and willing to pay a moderate interest. The pontiffs, therefore, at length resolved to allow the lending-houses to receive interest, not for the whole capitals which they lent, but only for a part, merely that they might raise as much money as might be sufficient to defray their expenses; and they now, for the first time, adopted the long-established maxim, that those who enjoy the benefits should assist to bear the burthen – a maxim which very clearly proves the legality of interest. When this opening was once made, one step more only was necessary to place the lending-houses on that judicious footing on which they would in all probability have been put by the inventor himself, had he not been under the influence of prejudice. In order that they might have sufficient stock in hand, it was thought proper to give to those who should advance them money a moderate interest, which they prudently concealed by blending it with the unavoidable expenses of the establishment, to which it indeed belonged, and which their debtors, by the practice a little before introduced, were obliged to make good. The lending-houses, therefore, gave and received interest. But that the odious name might be avoided, whatever interest was received, was said to be pro indemnitate; and this is the expression made use of in the papal bull.

All this, it must be confessed, was devised with much ingenuity: but persons of acuteness still discovered the concealed interest; and a violent contest soon arose respecting the legality of lending-houses, in which the greatest divines and jurists of the age took a part; and by which the old question, whether one might do anything wicked, or establish interest, in order to effect good, was again revived and examined. Fortunately for the pontifical court, the folly of mankind was still so great that a bull was sufficient to suppress, or at least to silence, the spirit of inquiry. The pope declared the holy mountains of piety, “sacri monti de pietà,” to be legal; and threatened those with his vengeance who dared to entertain any further doubts on the subject. All the cities now hastened to establish lending-houses; and their example was at length followed in other countries. Such, in a general view, is the history of these establishments: I shall now confirm it by the necessary proofs.

When under the appellation of lending-house we understand a public establishment where any person can borrow money upon pledges, either for or without interest, we must not compare it to the tabernæ argentariæ or mensæ nummulariæ of the Romans. These were banking-houses, at which the state and rich people caused their revenues to be paid, and on which they gave their creditors orders either to receive their debts in money, or to have the sums transferred in their own name, and to receive security for them. To assign over money and to pay money by a bill were called perscribere and rescribere; and an assignment or draft was called attributio. These argentarii, mensarii, nummularii, collybistæ and trapezitæ followed the same employment, therefore, as our cashiers or bankers. The former, like the latter, dealt in exchanges and discount; and in the same manner also they lent from their capital on interest, and gave interest themselves, in order that they might receive a greater. Those who among the ancients were enemies to the lending of money on interest brought these people into some disrepute; and the contempt entertained for them was probably increased by prejudice, though those nummarii who were established by government as public cashiers held so exalted a rank that some of them became consuls. Such banking-houses existed in the Italian States in the middle ages, about the year 1377. They were called apothecæ seu casanæ feneris⁶, and in Germany Wechselbanke, banks of exchange; but they were not lending-houses in the sense in which I here understand them.

Equally distinct also from lending-houses were those banks established in the fourteenth century, in many cities of Italy, such, for example, as Florence, in order to raise public loans. Those who advanced money on that account received an obligation and monthly interest, which on no pretext could be refused, even if the creditor had been guilty of any crime. These obligations were soon sold with advantage, but oftener with loss; and the price of them rose and fell like that of the English stocks, but not so rapidly; and theologists disputed whether one could with a safe conscience purchase an obligation at less than the stated value, from a proprietor who was obliged to dispose of it for ready specie. If the State was desirous or under the necessity of repaying the money, it availed itself of that regale called by Leyser regale falsæ monetæ, and returned the capital in money of an inferior value. This establishment was confirmed, at least at Florence, by the pontiff, who subjected those who should commit any fraud in it to ecclesiastical punishment and a fine, which was to be carried to the papal treasury: but long before that period the republic of Genoa had raised a loan by mortgaging the public revenues. I have been more particular on this subject, because Le Bret⁷ calls these banks, very improperly, lending-houses; and in order to show to what a degree of perfection the princely art of contracting and paying debts was brought so early as the fourteenth century.

Those who have as yet determined the origin of lending-houses with the greatest exactness, place it, as Dorotheus Ascanius, that is Matthias Zimmermann⁸, does, in the time of Pope Pius II. or Paul II., who filled the papal chair from 1464 to 1471; and the reason for supposing it to have been under the pontificate of the latter is, because Leo X. in his bull, which I shall quote hereafter, mentions that pope as the first who confirmed an establishment of this kind. As the above account did not appear to me satisfactory, and as I knew before that the oldest lending-houses in Italy were under the inspection of the Franciscans, I consulted the Annals of the Seraphic Order, with full expectation that this service would not be omitted in that work; and I indeed found in it more materials towards the history of lending-houses than has ever been collected, as far as I know, by any other person.

As complaints against usury, which was practised by many Christians, but particularly by the Jews, became louder and more public in Italy in the fifteenth century, Barnabas Interamnensis, probably of Terni, first conceived the idea of establishing a lending-house. This man was originally a physician; had been admitted to the degree of doctor; was held in great respect on account of his learning; became a Minorite, or Franciscan; acquired in that situation every rank of honour, and died, in the first monastery of this order at Assisi (in monte Subasio⁹), in the year 1474. While he was employed in preaching under Pope Pius II. at Perugia, in the territories of the Church, and observed how much the poor were oppressed by the usurious dealings of the Jews, he made a proposal for raising a capital by collections, in order to lend from it on pledges to the indigent, who should give monthly, for the use of the money borrowed, as much interest as might be necessary to pay the servants employed in this establishment, and to support it. Fortunatus de Copolis, an able jurist of Perugia, who after the death of his wife became also a Franciscan, approved of this plan, and offered to assist in putting it into execution. To be assured in regard to an undertaking which seemed to approach so near to the lending on interest, both these persons laid their plan before the university of that place, and requested to know whether such an establishment could be allowed; and an answer being given in the affirmative, a considerable sum was soon collected by preaching, so that there was a sufficiency to open a lending-house. Notwithstanding this sanction, many were displeased with the design, and considered the receiving of interest, however small it might be, as a species of usury. Those who exclaimed most against it were the Dominicans (ex ordine Prædicatorum): and they seem to have continued to preach in opposition to it, till they were compelled by Leo X. to be silent; while the Franciscans, on the other hand, defended it, and endeavoured to make it be generally adopted. The dispute became more violent when, at the end of a year, after all expenses were paid, a considerable surplus was found remaining; and as the managers did not know how to dispose of it, they at length thought proper to divide it amongst the servants, because no fixed salaries had been appointed for them. Such was the method first pursued at Perugia; but in other places the annual overplus was employed in a different manner. The particular year when this establishment began to be formed I have nowhere found marked; but as it was in the time of Pius II., it must have been in 1464, or before that period¹⁰. It is very remarkable that this pontiff confirmed the lending-house at Orvieto (Urbs Vetus) so early as the above year; whereas that at Perugia was sanctioned, for the first time, by Pope Paul II. in 1467. It is singular also that Leo X., in his confirmation of this establishment, mentions Paul II., Sixtus IV., Innocent VIII., Alexander VI. and Julius II.; but not Pius II. Pope Sixtus IV., as Wadding says, confirmed in 1472 the lending-house at Viterbo, which had, however, been begun so early as 1469, by Franciscus de Viterbo, a Minorite¹¹.