BEGINNINGS OF MODERN DISCOVERY
Such sporadic experiments as these have no sequential connection with the story of the evolution of the steam engine. The experiments which led directly on to practical achievements were not begun until the seventeenth century. In the very first year of that century, an Italian named Giovanni Battista della Porta published a treatise on pneumatics, in which the idea of utilizing steam for the practical purpose of raising water was expressly stated. The idea of this inventor was put into effect in 1624 by a French engineer and mathematician, Solomon de Caus. He invented two different machines, the first of which required a spherical boiler having an internal tube reaching nearly to the bottom; a fire beneath the boiler produced steam which would force the water in the boiler to a height proportional to the pressure obtained. In the other machine, steam is led from the boiler into the upper part of a closed cistern containing water to be elevated. To the lower portion of the cistern a delivery pipe was attached so that water was discharged under a considerable pressure. This arrangement was precisely similar to the apparatus employed by Hero of Alexandria in various of his fountains, as regards the principle of expanding gas to propel water. An important difference, however, consists in the fact that the scheme of della Porta and of de Caus embodied the idea of generating pressure with the aid of steam, whereas Hero had depended merely on the expansive property of air compressed by the water itself.
While these mechanisms contained the germ of an idea of vast importance, the mechanisms themselves were of trivial utility. It is not even clear whether their projectors had an idea of the properties of the condensation of vapor, upon which the working of the practical steam engine so largely depends. This idea, however, was probably grasped about half a century later by an Englishman, Edward Somerset, the celebrated Marquis of Worcester, who in 1663 described in his Century of Inventions an apparatus for raising water by the expansive force of steam. His own account of his invention is as follows:
"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 the 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."
It is unfortunate that the Marquis did not give a more elaborate description of this remarkable contrivance. The fact that he treats it so casually is sufficient evidence that he had no conception of the possibilities of the mechanism; but, on the other hand, his description suffices to prove that he had gained a clear notion of, and had experimentally demonstrated, the tremendous power of expansion that resides in steam. No example of his steam pump has been preserved, and historians of the subject have been left in doubt as to some details of its construction, and in particular as to whether it utilized the principle of a vacuum created through condensation of the steam.