ings of Institution of Civil Engineers, vol. cii., and of gas analysis in two recent numbers of Engineering, October 3 and 10, 1890.

How important it is for a manufacturer or millowner to know whether his boiler plant is really working efficiently, needs, the author feels, no argument. Coal costs money, and money saved in daily working expenses in these days of close competition often means the difference between profit or loss. It is, moreover, a duty every user of coal ought to take to heart -to lessen the waste of this precious commodity-seeing at what an alarming rate our supplies are being used up. Curves on figure 7 show rates of fuel consumption, water evaporation, gas temperatures, &c.

Notes on the Early History of the Steam-Engine and Steam Navigation. By WM. ALLAN CARTER, C.E.*

During the session 1888-89, when Mr Salvesen submitted his communication to the Society as to the question of Symington's right to be recognised as the inventor who had brought the question of Steam Navigation to a successful and practical issue, I made a half promise to the Society to bring forward some Notes on the Early History of the SteamEngine, but always hesitated to do so while I had more important and original communications to place on the billets. Having, however, been disappointed with two papers for this evening, I find myself forced to step into the breach, and trust you will accept the urgency of the situation as an excuse for any shortcomings in the fare I am able to provide.

Many of you may be aware that an effort has been made to provide a suitable memorial in Edinburgh to Symington, and I acted as local secretary to the committee. During the time we were collecting funds, I was frequently struck with the complete ignorance displayed as to the history and development of the steam-engine, even amongst engineers. By the present generation, the steam-engine is simply accepted as a

* Read before the Society on 8th December 1890.

fact; but, with regard to its past history, Watt and the steam-engine, Bell and the "Comet," seemed to sum up the whole of the general information floating about; and the popular idea is that Watt invented steam, and Bell invented the steamboat. It may, therefore, not be unprofitable, and, I trust, not uninteresting, to recapitulate some of the inciIdents which have marked the advance of the utilisation of steam in the steam-engine.

It is sometimes stated that the knowledge of steam, and even of its use as a motive power, was acquired long before the Christian era, and in many works written on the subject, Hero of Alexandria, who lived about 130 B.C., obtains the credit of having first invented a steam-engine. There is no doubt Hero was a philosopher, and wonderfully advanced for the times in which he lived; but, although he produced a piece of mechanism in which motion was induced by steam, he himself was ignorant of the fact, and knew nothing whatever regarding the properties of steam or the vapour of water. The mechanism on which Hero's credit rests is now sometimes seen in the form of a toy known as the Æolipile, or ball of Eolus. It consists of a little pot or boiler filled with water, from which a tube is carried to a ball free to revolve on an axis. The ball is furnished with two curved outlets at opposite sides, so that when steam is generated in the boiler and admitted to the interior of the tube, it finds an escape by the curved outlets, and the reaction of the steam against the atmosphere causes the ball to revolve. We have no reason to believe that Hero regarded this otherwise than as a toy or amusing physical experiment, and it is only in drawing on our imagination that we may come to fancy the classical philosopher as already hatching the idea of the steam-engine. It would be a mere waste of time to recount the sayings and writings of the wise men of that era, for, although great interest attaches to them, there is such a vagueness of language employed that no practical result can be arrived at, and it is more to our purpose to advance to a later period, when the history of men and their works becomes more reliable and lucid.

Leaving Hero, therefore, who flourished about 130 B.C.,

I make a sudden jump of more than thirteen hundred years, when I think it worth while to rest a moment to mention the name of Roger Bacon, not that he developed the idea of the steam-engine, but because some of the opinions he expressed seem in the present day to be almost prophetic. Bacon was born at Ilchester, in Somersetshire, in the year 1214. He received his education at Oxford, and afterwards went to Paris, where he continued his studies and took a theological degree. The physical sciences had great attractions for him, and, notwithstanding the difficulties put in his way by fanatical religious brethren, he continued to study them earnestly; and it is related of him that, to satisfy his craving for knowledge, he laboured to acquire a command of Latin, Greek, Hebrew, and Arabic in order to read in the original language such scientific works as were then obtainable. He thus acquired as great a knowledge as then existed of mathematics, astronomy, physics, and chemistry, and gathered around him the young men of his order, by whom he was known as the "Admirable Doctor." He studied the subject of lenses, and actually made spectacles for the use of the aged brethren; he enunciated the theory of the telescope, a theory which only bore fruit about 400 years afterwards, when the great Galileo had brought his genius to bear on it. The manufacture of gunpowder attracted his attention, and he seemed to foresee the wonderful power with which it was vested, for he writes that "it is sufficient to ignite a very small quantity of this substance to produce much light, accompanied by a horrible noise. By this means a town or a whole army may be destroyed." In his great work, The Opus Major, we find the following most significant lines:"We will be able to construct machines which will propel large ships with greater speed than a whole garrison of rowers, and which will only need one pilot to direct them; we will be able to propel carriages with incredible speed without the assistance of any animal, and we will be able to make machines which, by means of wings, will enable us to fly in the air like birds." Compare the large ship propelled by a machine with a modern steamship! the carriage travelling with incredible speed without the assistance of any

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animal with the modern railway train, and the machine with wings to soar in the air like a bird with a modern balloon, and we cannot help being impressed with the wonderful manner in which these words of Bacon have been verified. At the same time, we must admit that Bacon had no notion of how these wonders were to be brought about, and his predictions are most probably due to the fact that he appreciated the ignorance which surrounded him, and foresaw that that ignorance would sooner or later give way under the repeated assaults of an ever-developing human intellect, and that, as ignorance gave way, wonderful things such as he suggested would probably result. It is a pleasant thing to imagine the brilliant light of genius shining out in the midst of darkness whole centuries in advance of all its surroundings; but we require to be very cautious not to attribute too much to such eccentricities of genius, as by so doing we are apt to wander from the paths of truth, and lose ourselves in a mere imaginary sentimentalism.

When we consider the immense value of the steam-engine to the civilised nations of the world, it is not unnatural that there should be a certain rivalry as to who shall be credited with the invention. In England, Savery, to whom I will allude to at greater length immediately, invented a steamengine in 1697, and claimed for himself the credit of being the original inventor; this claim was resisted by Denis Papin, a Frenchman. Papin, however, was a Protestant and a heretic, so his countryman, the Abbé John de Hautefeuille, not wishing the credit of such an invention to be allowed to any one outside the pale of the Church, contested Papin's claims, and desired to have the credit to himself. It was then that the English people entered into the dispute, and claimed priority for the Marquis of Worcester, on the strength of his having published his century of inventions in 1663. Our French neighbours then went a little further back, and endeavoured to instal their country man, Salomon de Caus, as the great original inventor, he having written a work in 1615 on the "Properties of Moving Forces." Salomon de Caus was an ingenious engineer and architect, who did much good work in his day, but whose opinions were simply, those of his own day.

He had no conception of what steam was; his knowledge was very little in advance of that of Hero, and the great engine on which his renown was based consisted of a spherical boiler (fig. 1), which had to be filled with water, and having a tube reaching almost to the bottom. When fire was applied to the boiler, the pressure of steam on the upper surface of the water forced the water up the tube to form a little fountain. But Salomon de Caus himself was not aware of the action of the steam, and in fact could not distinguish between steam and heated air, the latter being the term then employed for steam, just as in the days of Hero. In recent times it has been the popular belief that Salomon de Caus died a raving lunatic, and as a good instance of how a popular error may be spread, I relate how this belief came to be held. In 1834, Henry Berthaud, one of the editors of a French paper, was publishing in his paper a romance in which one of the characters was a madman, and he instructed Gavarni, the engraver, to supply an engraving of a raving madman in his cell. The engraving, however, was not executed in time, and the story had to be published without it. Some time afterwards the engraver, having finished his task, sent the picture-block to Berthaud, to whom it was now useless. But, as he considered it a silly thing to possess an engraving and not make use of it, he drew up a fictitious letter, purporting to have been written by Marion Delorm, the mistress of the Marquis of Worcester, in which it was stated that the Marquis and herself, in visiting the prison of Bicêtre, had seen Salomon de Caus confined behind strong bars, shouting out "I am not mad! I have made a discovery which will change the whole world!" and the engraving was published to illustrate the letter. Artists, authors, dramatists, without taking trouble to verify this history, have made poor Salomon de Caus the subject for their pen and pencil, depicting him in all the terrors of lunacy, whereas he died quietly in Paris in the full possession of all his senses, and holding the appointment of engineer to Louis XIII. When Berthaud confessed, in 1847, the part he had played in this little fiction, he had some difficulty in making the public believe him. They much preferred Salomon de Caus as the lunatic.