Source: The Life of John Ericsson, Vol I, p. 71
Author: William Conant Church, Editor of the Army and Navy Journal
Date: New York, Charles Scribners's Sons - 1906
Failures to introduce more economical methods in the use of steam seem to have intensified Ericsson's determination to find a substitute for the steam engine. He had never laid aside the expectations connected with his earliest invention of a flame-engine ; indeed, their influence may be traced through all the experiences of his long and busy life.
They at one time led him very near to the danger-line of speculation as to the possibility of perpetual motion. He knew of no engineer, he said, who had not at some time been fascinated with this conceit. In the mechanical operations of nature there seemed to be, with continual waste, some law of compensation at work, and Ericsson was led to the conclusion that there exists in nature a principle of absolute reproduction of mechanical force. For this he sought as for the pearl of great price.
The dynamical theory of heat was not accepted when his studies began, and his experiments led him to believe that heat was an agent exerting mechanical force without itself undergoing change. In this opinion he was supported by the declaration of his countryman, Professor Ilarvefeldt, a famous mathematician, that there was nothing in the accepted theory of heat to prove that a common spirit-lamp might not be sufficient to drive an engine of one hundred horsepower.
Ericsson hoped at least to so lessen the consumption of fuel in the production of mechanical power as to extend the range of manufacturing industries into regions not furnished witli fuel, as well as to remove farther into the future the inevitable period when the world's coal supply will be exhausted.
The smoke-jack, setting figures in motion by the action of the rarefied air rising from a hot stove, is the simplest expression of the mechanical force Ericsson sought to control in his " caloric engine."
As early as 1699, the Frenchman, Amontons, had applied this principle to a wheel moved by a column of heated air. A century later, in 1797, an Englishman, Glazebrook, patented the idea of transferring the heat in an air-engine from the hot air going out after doing its work to the cool air coining in to take its place and continue the circuit.
The same idea is found in Lilley's English patent of 1819, and in the hot-air engines of Rev. Dr. Robert Stirling, to whom the credit for its conception is usually given.
Stirling, who was a clergyman of Ayrshire, in the year Ericsson arrived in England, 1826, applied for a patent for an air-engine representing what is known as the regenerative principle. The fact that Ericsson opposed this application shows what he thought of Stirling's claim to originality.
His opposition was unavailing, for a patent is on record as having been granted in the following year. The reverend gentleman describes his apparatus for receiving and transferring the heat as similar in principle to " Jeffrey's Respirator," then used by consumptive patients to transfer the heat contained in the air exhaled from the lungs, to the cool air inhaled to take its place.
Stirling's device was imperfect, and his engine, as Chambers states, was crude and incomplete.
Nevertheless, it greatly annoyed Ericsson by its claims to priority.
His own application of a " regenerator " was first made in 1833, when he invented and patented in England, France, the United States, and other countries a " caloric engine " with an " organ-pipe regenerator " consisting of a faggot of small copper tubes.
Through these tubes the heated air passed on its way out of the working cylinder to the " cooler," and on the outside of the tubes the cold air from the cooler passed in an opposite direction on its way into the cylinders. Thus, there was a transfer of heat from the air going out, after doing its work, to the cold air coming in to take its place over the furnace. This transmission of heat from the outgoing to the incoming air reduced to the minimum the waste of heat, and consequently of power.
This " regenerator " was the result of many years of study and careful experiment to determine the most effective means of preventing the loss of heat, for Ericsson had discovered that it was necessary to maintain the air in his working cylinder at a high temperature until the end of the piston's stroke. The cylinder for compressing the air was surrounded by a water-jacket, to keep down the temperature and protect the leather fastenings from the high heat.
An experimental caloric engine of five horse-power, and with a working piston fourteen inches in diameter, was set in motion at London, in 1833, and at once excited extraordinary interest. Sir Richard Phillips has recorded, in his " Dictionary of the Arts of Life and of Civilization," the " inexpressible delight" with which he witnessed the workings of this machine.
With a handful of fuel applied to the very sensible medium of atmospheric air and a most ingenious disposition of its differential powers, he beheld a resulting action in narrow compass, capable of extension to as great forces as ever can be wielded or used by man. The principle of the new engine, consists in this, that the heat that is required to give motion to the engine at the commencement, is retained by a peculiar process of transfer, and thereby made to act over and over again, instead of being, as in the steam-engine, thrown into a condenser, or into the atmosphere as so much waste fuel.
And the well-known phenomenon that temperature, or quality of heat, is always equalized between substances, however unequal they may be in density, forms the basis of the new application of heat.
Dr. Alexander Ure, author of the technical dictionary bearing his name, was another believer in the caloric engine, asserting that this invention would throw the name of James Watt into the shade.
The little engine was in its day the sensation of London in scientific and mechanical circles. It was visited by a large number of men of reputation, as well as by curious crowds of sightseers, and for many years after was a theme of discussion in engineering circles. Among those who called to visit this new motor was Lord Althorp, afterward Earl Spencer, then Chancellor of the Exchequer and Ministerial leader in the House of Commons.
He was accompanied by Mr. Brunel, the distinguished engineer and citizen of two worlds, whose name is associated in London with the Thames Tunnel, and in New York with the Bowery Theatre of his designing. Mr. Brunel was not favorably impressed.
Believing that his judgment was founded on an erroneous impression of the new power, Ericsson entered into a lively discussion with him. This was continued by correspondence, with the usual result of establishing each party to the controversy more firmly in his own opinion.
Professor Michael Faraday, however, declared by John Tyndall to be " the greatest experimental philosopher that the world has ever seen," was prepared to give a hospitable welcome to Ericsson's theories and studied his new engine with the greatest attention and interest. He refused to accept the condemnation passed upon it by nearly all the leading scientific men of that day, and denied that the principle on which it was based was unsound.
Ericsson counted with great confidence upon the results expected to follow Faraday's advocacy of his invention, for the distinguished investigator announced his intention of delivering a lecture upon it at the theatre of the Royal Institution, London. A large audience was attracted by this announcement, including many gentlemen of distinguished scientific reputation.
Just as Faraday was preparing to appear upon the platform he came to the conclusion that he had made a mistake as to the principle of the expansion of air upon which the action of the machine was dependent. He accordingly commenced his lecture, greatly to the disappointment of Ericsson, by the announcement that he was unable to explain why the engine worked at all. He confined himself, therefore, to an explanation of the regenerative apparatus, for using the heat over and over again in the production of force.
To this part of the invention he rendered ample justice, and explained it in that felicitous style to which he is indebted for the reputation he deservedly enjoys, as the most agreeable and successful lecturer in England. (A Lecture on the Late Improvements in Steam Navigation and the Arts of Naval Warfare, with a brief Notice of Ericsson's Caloric Engine, delivered before the Boston Lyceum, by John O. Sargent. New York, 1844).
The caloric engine of 1833 was a sore puzzle to the savans of that day. They were unwilling to accept Ericsson's theories and claims concerning it, but their own opinions as to the nature of heat were not sufficiently settled to enable them to explain clearly their skepticism.
Aristotle had told them that the first principle in nature, through all of its manifestations, was unity, and that these manifestations were always reducible to motion as their foundation, and Bacon had declared that " the very essence of heat or the substantial self of heat is motion," but the science of thermodynamics was not yet established on the present basis of theory and experiment.
It was not until sixteen years later, in 1849, that Joule, in his paper before the Royal Society, presented his final conclusion as to the mechanical equivalent of heat, and established the existence of an exact relation between heat and force. The regenerator was correct in theory, as subsequent experience has shown, but its advantages were to some extent neutralized by the obstruction it offered to the free passage of air.
Other practical difficulties presented themselves in an engine that required 450° F. of heat instead of the temperature of 212° at which water is turned into steam. Oxidation soon destroyed the pistons, valves, and other working parts. Ericsson's use of high temperature in an air engine seems to have suggested the use of a similar apparatus to increase the temperature of steam.