Talk:Thomas Newcomen/Material from Wikipedia user Dr. Gabriel Gojon/The Leibniz-Papin Collaboration

The Leibniz-Papin Collaboration Papin began to tackle the problem of "making very large tubes" by studying the means of refining ores more efficiently, and of manufacturing cylinders with appropriately smooth surfaces,i.e., to create the appropriate MACHINE TOOLS which would allow him to realize his ideas. This led him to the invention of an improved furnace capable of reaching higher temperatures with a more efficient consumption of fuel. Papin used another of his inventions, the Hessian bellows, to generate a forceful down-draft in his furnace, thereby eliminating smoke and allowing a complete burn (see Figure 6). By 1695, Papin had adapted this hotter furnace to the rapid production of high-pressure steam, by constructing the furnace so that the fire surrounded the water, allowing the maximum surface area of water to be heated directly.

With this discovery, Papin was prepared to initiate a qualitative technological advance -not a linear extrapolation from his 1690 results, such as building larger atmospheric engines, but a proposal to directly harness the violent force of the expanding steam.

In a letter dated April 10, 1698, Papin apologized to Leibniz for not having written sooner, and explained that a new project, commissioned by his employer, the Landgrave of Hesse, had taken up most of his time:

Monsgr. le Landgrave formed a new plan, very worthy of a great Prince, to attempt to discover where the salt in salty springs comes from. To reach the bottom of this, it would be very advantageous to be able to easily draw out a great quantity of water to a considerable height. I've made many tests to try to usefully employ the force of fire to this task; some succeeded so well that I was persuaded that this force could be applied to things much more important than raising water. Consequently, I've given myself totally to this work, knowing the great difficulties always to be met with in such enterprises and which can't be overcome without an extraordinary diligence. I'm presently having a new furnace built of which I've spoken to you before .... I'm building it simply to make certain large retorts of forged iron which will be very useful to produce the great effects that I expect from the force of fire. For this furnace I've also built a large Hessian bellows more perfect than those I've made before. And thus one thing leads to another.... [emphasis added]. In his reply four days later, Leibniz asked if Papin's method of raising water "is based on the principle of rarefaction which you published before, or if it is based on some other principle; I also have a thought about it, but I want to make a little test of it in order to consult you on its performance." Papin's historic answer follows (July 25,1698): "The method in which I now use fire to raise water rests always on the principle of the rarefaction of water. But I now use a much easier method than that which I published. And furthermore besides using suction, I also use the force of the pressure which water exerts on other bodies when it expands. These effects are not bounded, as in the case of suction. So I am convinced that this discovery if used in the proper fashion will be most useful .... For myself I believe that this invention can be used for many other things besides raising water. I've made a little model of a carriage which is moved forward by this force: And in my furnace it shows the expected result. But I think that the unevenness and bends in large roads will make the full use of this discovery very difficult for land vehicles; but in regard to travel by water I would flatter myself to reach this goal quickly enough if I could find more support than is now the case .... It gave me much joy to find that you also have some plans to put the moving force of fire to use, and I strongly hope that the little test you told me of succeeded to your satisfaction [emphasis added]. Leibniz's concern, however, was much greater than simply using the "force of fire" to propel ships and carriages. He saw in Papin's work the unique experiment capable of irrefutably establishing the truth of his dynamical science, as well as advancing that science, by the process of applying its principles to the measurement of the thermodynamic efficiency of Papin's machines. This is the "little test" referred to in the letters above. Leibniz wrote to Papin (July 29,1698):

"I understand very well that the force of expanding water will do much more than air pressure will do when the steam is condensed, and this is exactly what I have thought as well in regard to gunpowder .... But in regard to water the strain of its expansion will be less violent, [so] it would be good to see if there aren't other fluids which would be even better than water. But water has the advantage that it costs nothing, and is available everywhere. My plan would be to do a test to discover if expanding water can usefullyn raise more than a column of air. But I lack workers here, and I'm too distracted .... But I'm now very glad to find out that you've already made the relevant experiment, and that therefore you know approximately what the force of the steam is relative to the heat and to time [emphasis added]." Papin replied with a progress report on the construction of his engine, promising that once it was completed: "I will try also to make observations on The degree of heat [chaleur] required to make a given effect with a given quantity of water. But up to the present all that I've been able to do, by the expansion of the steam, is to raise water to 70 feet, and to observe that a small increase in the degree of heat is capable of greatly augmenting the magnitude of the effect. And this convinces me that if these machines are perfected so that very great degrees of heat can be used, one will be able to create a greater effect with a pound of water than with a pound of gunpowder [emphasis added]."