Chap. 5.]

Classification of Modern Steam Engines.

425

elastic force or the condensation of steam could be beneficially applied to give motion directly to solids, some plan very different from that of Branca was required-one by which the fluid could be used in close vessels. Now there is in the whole range of mechanical combinations but one device of the kind yet known, and it has but few modifications, viz. a piston and cylinder. Experience has proved, that of all contrivances for transmitting the force of highly elastic fluids to solid bodies, this is the best. Thus guns are cylinders, and bullets are pistons, fitted to fill the bore and at the same time to move through the straight barrels. It is the same, whatever the impelling agent may be; whether gun-powder, steam, or compressed air. The air-guns of Ctesibius are the oldest machines of the kind on record, and from them we see that the ancients had detected this mode of employing aëriform fluids.

Steam-engines simply considered are but modifications of guns. In the latter, the bullet or piston is driven entirely out of the cylinder, and in one direction only, because the intention is to impart the momentum to a distant object at a blow: but by the former the design is to derive from the moving bullet a continuous force; hence it is not allowed to leave the cylinder, but is made to traverse incessantly backwards and forwards within. In order to transmit its impetus to the outside of the cylinder and to the objects to be acted upon, a straight rod is attached to it, and made to slide through an opening in one end of the cylinder. It is by means of this rod that motion is imparted to the machinery intended to be moved. All the mechanism, the wheels, cranks, shafts, drums, &c. of steam-engines are but appendages to the cylinder and piston; they may be removed and the energy of the machine still remains; but take away either cylinder or piston and the whole becomes inert as the limbs of an animal whose heart has ceased to beat. Therefore it is the working cylinder and piston alone that give efficiency to modern steam-engines; and it is to those persons who contributed to introduce them, that the glory attending the invention of these great prime movers is chiefly due.

Whatever may be said respecting more ancient applications of steam as a moving power, modern engines are one of the results of the discovery of atmospheric pressure. All the early ones of which descriptions are extant were rather air than steam machines, not being moved by the latter fluid at all. Their inventors had no idea of employing the elastic force of steam, but confined themselves to the atmosphere as a source of motive force: hence they merely applied steam in lieu of a syringe to displace air from a cylinder, that, when the vapor became condensed by cold into a liquid, the atmosphere might force down the piston. That this was the way in which modern engines took their rise appears, further, from the same feature being retained in a great portion of them to this day. They are now ranged in three classes-1st atmospheric, 2d low pressure, and 3d high pressure engines; and this we know is the order in which they were developed. In the first, the power is derived exclusively from the atmosphere, the vapor employed being used only as a substitute for an air-pump in making a vacuum under the piston. In process of time the second was devised, in which the elastic force of steam is made to act against one side of the piston, while a vacuum is formed on the opposite side. The next step was to move the piston by the steam alone, and such are named highpressure engines. The term steam-engine is therefore not so definite as some persons might suppose, since it is not confined to those in which steam is the prime mover. Had it not been for Torricelli's discovery, it is possible that we should never have known any other species of steamengine than those of the third class; and hence we repeat, that whatever

426

Guerricke's Illustration of Atmospheric Pressure.

[Book IV. may be thought of engines made previous to the 17th century, those of modern days were obviously derived from atmospheric ones of the first class, while these in their turn were very likely deduced from the apparatus described in the next paragraph.

Otto Guerricke, of whom we spoke at page 190, one of the earliest, and as far as mechanical ingenuity went perhaps the most gifted, of the early

elucidators of atmospheric pressure, exhibited in his public experiments at Ratisbon, in 1654, the following application of that pressure as a motive force. A large cylinder, A, was firmly secured to a post or frame. It was open at the top and closed at the bottom, and had a piston accurately fitted to work in it. A rope was fastened to the piston-rod and passed over two pulleys, B C, as represented, by which was suspended a scale, D, containing several weights. When the air was withdrawn from the lower part of the cylinder, the pressure of the atmosphere depress ed the piston and raised the scale and weights. To vary the experiment, the weights were removed and twenty men were employed to pull at the rope with all their strength; but as soon as a vacuum was made by the small air-pump attached to the bottom of the cylinder, the piston descended, notwithstanding all their efforts to prevent

No. 191. Guerricke. A. D. 1654.

it.

This is the oldest apparatus on record for transmitting motion to solids by a piston. We can however hardly believe that it was the first devised for the purpose. It would be strange if it were; for whatever may have been the nature of Anthemius's, Garay's, and other old machines in which steam was the active principle, pumps and syringes had been too common, and experiments with them too frequent, for such a device to have been unknown. Such men as Aristotle and Archimedes, Ctesibius, Heron, Roger Bacon and their successors, were all aware that a syringe presented the same phenomenon as Guerricke's apparatus, when the piston was drawn up while the discharging orifice was closed: the same thing was also observed with common pumps when the suction-pipes were either closed or choked. Experiments therefore to illustrate the force thus excited were in all probability made, and with apparatus similar to that of the Prussian philosopher, long before his time, although no account of them is extant. But if even such had been made, they would not lessen in any degree the merit of Guerricke, since his experiment undoubtedly originated with himself, and all knowledge of similar ones had been lost. In this device we behold the same moving force, and the same mechanism for applying it, as were subsequently adopted in steam-engines, which at first were little more than copies of this: for example, had a loaded pump-rod been suspended to the rope instead of the scale and weights, the apparatus would have differed from Newcomen's engine only in the mode of exciting the atmospheric pressure. To Guerricke, therefore, is due the credit of having not only pointed out the power which alone gave efficiency to the first steam-machines, but also of devising the most effec

Chap. 6.] Old Inventors concealed their Discoveries.

427

tual means of employing it. No one could, we think, claim an equal degree of merit for simply applying (not inventing) another mode of producing a vacuum under the piston; but without insisting on this, it may be observed that even at present, in all low-pressure engines, the vacuum is made just as Guerricke made it, viz. by an air-pump; so that the impress of his genius on the steam-engine is no more obliterated in this respect than it is in others. Every unbiassed mind will therefore admit, that an honorable place in its history should be assigned to the philosopher of Magdeburg.

CHAPTER VI.

Reasons of old Inventors for concealing their discoveries-Century of Inventions-Marquis of Worcester-His Inventions matured before the Civil Wars-Several revived since his death-Problems in the "Century" in older authors-Bird roasting itself-Imprisoning Chair-Portable FortificationsFlying-Diving-Drebble's Submarine Ship-The 68th Problem-This remarkably explicit-The device consisted of one boiler and two receivers The receivers charged by atmospheric pressure-Three and four-way cocks-An hydraulic machine of Worcester mentioned by Cosmo de Medicis-Worcester's machine superior to preceding ones, and similar to Savery's-Piston Steam-Engine also made by himCopy of the last three Problems in the Century-Ingenious mode of stating them-Forcing-Pumps worked by Steam-Engines intended-Ancient Riddle-Steam-Boat invented by Worcester-Projectors despised in his time-Patentees caricatured in a public procession-Neglect of Worcester-His deathPersecution of his widow-Worcester one of the greatest Mechanicians of any age or nation-Glauber.

As yet we have not met with any definite description of a steam-engine in actual use. This can only be accounted for from the fact that old inventors were all jealous of the printing-press. They believed their interest required concealment on their part, that pirates might not rob them of their labors. They have been blamed for this, and so have some modern mechanics, but we think without reason; for, to obtain satisfaction at law in such cases, was formerly as difficult as it is now in most cases. To have to purchase justice, as in a lottery, with money, is bad in itself, and worse because those without money cannot obtain it; but to have to give more for it than it is worth, if perchance it be awarded, is a disgrace to enlightened nations-an evil that savages would not for a moment endure. It is thus that law, though ordained to promote justice, is so prostituted as not only to defeat the object for which it was designed, but to cherish the grossest injustice. It has always been a bar to the progress of the arts. The difficulty and expense of obtaining and preserving an exclusive right to their inventions-that is, to their own property-have induced inventors more or less, in every age, to conceal their discoveries till death, and even then to destroy all records respecting them.

When old inventors were solicitous of public patronage, instead of establishing their claims to it by explaining the principles and operations of their machines, they contented themselves with enumerating their uses and good qualities merely. They proclaimed the great things that could be done, but studiously concealed the modes and means of doing them: hence new inventions were sometimes announced enigmatically, the moving or constituent principles being so obscurely hinted at that few readers

428

Marquis of Worcester.

[Book IV. could apprehend them. Of this mode of exciting public attention, the account of the engine of motion in the last chapter is an example; and several more may be seen in the pamphlet published by the Marquis of Worcester, in 1663, entitled "A Century of the Names and Scantlings [outlines or hints] of such Inventions as at present I can call to mind to have tried and perfected; which, my former notes being lost, I have, at the instance of a powerful friend, endeavored, now in the year 1655, to to set down in such a way as may sufficiently instruct me to put any of them in practice." This book is made up of one hundred inventions, numbered from one upwards. It contains a distinct reference to a working steam-machine for raising water, and also hints by which its nature and construction are pretty clearly ascertained. There is some reason to believe that the modern high-pressure engine is also referred to. From the circumstance of the author having figured largely in the civil wars, he having been an enthusiastic adherent of Charles I. and of monarchy, his character and that of his book have been represented in the best and worst of lights. By his enemies he was held up as false and unprincipled in the highest degree; by his friends, as chivalrous and of unspotted honor. The "Century" has been denounced as a scheme to impose on the credulity of mankind-the dream of a visionary-and Hume, in his History, goes so far as to name it "a ridiculous compound of lies, chimeras, and impossibilities." On the other hand, it has been received by many (and generally by practical men) in the light in which the author represents it, viz. as a memorial of inventions actually put in practice by him-such as he had really "tried and perfected."

With the political conduct of Worcester we have nothing to do. He naturally enough supported that system by which he and the rest of the Lords acquired and entailed their exclusive privileges; among which the abominable one of being legislators by birth was perhaps the most odious and unnatural. On the fall of the king he retired to the continent, but, at the request of Charles II, ventured to visit London in disguise in 1656. Being discovered, he was arrested, and confined in the Tower until the reëstablishment of monarchy in 1660. He died in 1667.

We have no positive information respecting the time when he commenced his mechanical researches. There is however reason to believe that most, if not all, the inventions enumerated in the "Century" were matured before the civil wars broke out, and consequently that the account of them was drawn up, as he declares, in 1655. No. 56 he observes was tried before Charles I, Sir William Balfour, and the Dukes of Richmond and Hamilton; and this could not have been later than 1641, for Balfour was dismissed that year. In addressing the Century to Parliament, he mentions having had "the unparalleled workman, Caspar Kaltoff," in his employment "these five and thirty years," and who was at that time (1663) engaged in his service. This carries back his experiments to 1628. Some of his "water-works" were in operation in his father's castle (at Ragland, in Wales) at the commencement of the Long Parliament, (1640) for by their sudden movements he is said to have frightened certain adherents of the Parliament, who went to search the castle for arms. The nature of these works is not indicated, except that they consisted of "several engines and wheels," and that large quantities of water were contained in reservoirs on the top of a high tower. Whether steam was the agent employed to raise this water is unknown. It could not have been if the tradition, credited by some writers, was true, viz. that his attention was first

a The Century is copied in vol. xiii of Tilloch's Phil. Mag.; and the editor remarks, "this little tract was first published in 1655."

Chap. 6.]

Century of Inventions.

429

drawn to the employment of steam by observing, while a prisoner in the Tower, a pot-lid raised or thrown off by it. If this was the case, then no dependence can be placed on Worcester's assertion, that the whole Century was written in 1655; but there is no reason to question his veracity in this respect. On the contrary, the tradition is obviously a fable; one that has been applied to others as well as to him.

Although many of the devices in the Century appear at first sight extremely absurd, and others impossible, yet every year is producing a solution of one or more of them. One half, at least, of the number have been realized; among which are telegraphs, floating baths, short-hand, combination locks, keys, escutcheons and seals, rasping mills, candle-moulds, engines for deepening harbors and docks, contrivances for releasing unruly horses from carriages, torpedoes, diving apparatus, floating gardens, bucket engines, (see page 64 of this volume) universal lever, repeating guns and pistols, double water screws (p. 140 of this vol.) abacus, portable bridges, floating batteries &c. besides his applications of steam, which will be noticed more at large farther on.

It must not be supposed that Worcester was the first projector of every problem in the Century, although his solutions may have been peculiar to himself. The greater part may be found in the works of Porta, Fludd, Wilkins, and others of his predecessors and contemporaries; so that the charges of absurdity brought against many of them are not attributable to him alone. Indeed, the Century is in a great measure free from those puerile conceits that abound in old authors. No. 3 he names "a one-line cypher," that is, a character composed of a single line, which by its position was made to represent each and every letter of the alphabet. (Now used in short-hand.) No. 4 is an improvement, and consists in substituting points or dots in place of lines. No. 5, "a way by circular motion, either along a rule or ringwise, to vary any alphabet, even this of points," &c. Now these three systems were explained and illustrated by diagrams in detail, twenty-two years before the publication of Worcester's book, by Bishop Wilkins, in his "Mercury, or secret and swift Messenger," a tract printed in 1641. The eleventh chapter treats "of writing by invented characters"-" how to express any sense either by lines, points or figures." The last was by arranging the points or dots in the forms of circles, squares, triangles, &c. Wilkins speaks of the whole as an old device. Another problem in the Century is "a universal character." This had been often attempted, and Wilkins wrote also upon it. Another, "a waterball," to show the hour of the day. There were some singular specimens of these clocks in Serviere's museum, which was celebrated for its collection of mechanical devices, and which doubtless Worcester had often visited. (See page 285, and note foot of page 63.) The universal lever, No. 26 of the Century, he admits having seen at Venice, and the bucket engine (No. 21) at Rome. It is probable he derived his " 'imprisoning chair" from the same place; for there was in his time, as well as since, a

a There is a singular one in book xiv of Porta's Magic, "Of a bird which roasts itself;" which, had Worcester mentioned, few would have credited without the explanation. "Take a wren and spit it on a hazel stick, and lay it down before the fire, the two ends of the hazel spit being supported by something that is firm; and you'll see with admiration the spit and the bird turn by little and little, without discontinuing, till 'tis quite roasted." This, says Ozanum, was first found out by Cardinal Paloti, at Rome. The motion may be accounted for on a similar principle as the rotation of glass tubes when supported at each end before a fire, and even when inclined against the fire-place with one end on the hearth, viz.: the heat, being applied to one side only, causes the tubes to bend, and consequently to preponderate and thus turn round. See Phil. Trans. vol. xxx-Abridg. vol. x 551.