Conservation and Innovation : Helmholtz's Struggle with Energy ...

More documents

Recommendations

Info

through his own framework than in a specific determination of the equivalent. In this long chapter the use of the formalism is limited to a discussion of Clapeyron's and Holtzmann's laws and the whole approach is rather qualitative. Strangely enough, the results here will not be as far-reaching as in the next two chapters. The lack of a determination of the mechanical equivalent in this fourth chapter probably justifies Helmholtz's later claim 154 that the Erhaltung was meant more as a review and a synthesis of contemporary physical knowledge than to produce original experimental results. Helmholtz started applying his method of looking for actual compensations (equivalents) to an apparent loss of "force" (energy). Through his own principle of conservation of force he identified the compensation for the loss of living force in inelastic collision and in friction with a supposed increase of tension forces, namely internal elastic forces, due to the variation of "the molecular constitution of the bodies" 155 and with acoustical, thermal and electrical effects. First comes the case of collision of non-elastic bodies: the vis viva lost must reappear as an increase of elastic forces (tension forces), as heat and sound. In the case of friction instead we have increase of elastic forces, heat and electricity. If we do not take into account molecular effects and electricity, we can pose two great problems: a) does a loss of vis viva correspond to an equivalent amount of heat?; and then: b) how can we frame heat in a mechanical interpretation? 156 The first question is connected to a "correlation" approach, the second one is specific to Helmholtz's program. Surprisingly the first question is disposed of very rapidly, in a few lines, and without definite results. Helmholtz, who did not know of Mayer's and Colding's research, asserted that to this problem "perhaps" too few efforts have been dedicated. He actually only cited a paper of Joule (1845) 157 and recalled his attempts at establishing a mechanical equivalent through the heat produced by the friction of water in narrow tubes and in vessels (the famous paddle wheel experiment). Helmholtz asserted that Joule's result in the first case is that the heat needed to raise by 1°C 154 Helmholtz WA 1 P.74. 155 Helmholtz Erhaltung P.26. 156 Helmholtz Erhaltung P.27 157 Joule, James P. "On the Existence of an Equivalent Relation between Heat and the Ordinary Forms of Mechanical Power." In Phil. Mag ser3, XXVII, p.205, reprinted in Scientific Papers Pp.202-5 , signed August 6,1845.
the temperature of 1 Kg of water can raise 452 Kg to 1 meter, and 521 Kg in the second case 158. Helmholtz's judgement on Joule's work, the only original experimental determination of the mechanical equivalent of heat cited in the Erhaltung, is very severe. For Helmholtz, Joule's measurements are not adequate to the "difficulties of the research" and thus it is not possible to accept the results as correct: "probably the figures are too high". Helmholtz's criticism of the only empirical evidence corroborating his own theoretical approach is surprising. Koenigsberger later asserted 159 that he had read Joule's papers just before publishing his own essay, but nevertheless, being a good experimentalist and being involved in experimental physiological research in a closely related subject, the judgement of inaccuracy referred to experiments that were indeed very accurate requires an explanation. Tyndall, trying to provide such an explanation in 1853, in a note 160 to the English translation of the Erhaltung , warned the reader that Helmholtz was only acquainted with Joule's early works; Tyndall again in 1863 161, during the famous controversy with Tait and Thomson on the Mayer or Joule priority, quoted Helmholtz's remarks and to justify them asserted that Joule's measurements of the equivalent in 1843 162 varied between 1040 and 587 foot pounds. But actually Helmholtz, in the passage of the Erhaltung we are dealing with, did not refer to Joule's 1843 but to his 1845 paper. In this paper Joule gave the results of the paddle wheel experiments (890 foot pounds) and recalled his previous results 163: 823 fp. in 1843 from magnetoelectrical experiments, 795 fp. in 1845 from the 158 For a discussion of these figures see below. 159 Helmholtz "On the Interaction of Natural Forces and recent Physical Discoveries bearing on the same" Phil Mag XI, 1856:489-518, on p.499; see also Helmholtz Autobiographical Sketch P.12; Koenigsberger HvH P.44. 160 Helmholtz, Hermann. "On the Conservation of Force; a Physical Memoir." Trans.John Tyndall. In Scientific Memoirs-Natural Philosophy , Tyndall and Francis (eds.), vol. I, p.II, London,1853 :114-162; P.131. 161 Tyndall, John. Philosophical Magazine 1863 Pp. 375-6 162 Joule, James. "On the Caloric Effects... " 1843. Repr in The Scientific papers Vol.1. Pp.123-159. Pp.151 and 153. 163 Joule "Equiv Relat" quoted n.244, P.204 repr.
Page 1 and 2: Fabio Bevilacqua Conservation and I
Page 3 and 4: different formulations 4 and priori
Page 5 and 6: and interesting results, despite th
Page 7 and 8: principle of correlation is express
Page 9 and 10: principle to the existing empirical
Page 11 and 12: the origin and meaning of the princ
Page 13 and 14: Whether physiological research, apa
Page 15 and 16: In a discussion on the origins of a
Page 17 and 18: his "Wärme" that one of the differ
Page 19 and 20: generate a determined equivalent of
Page 21 and 22: "Bericht", despite the application
Page 23 and 24: experiments in the most disparate b
Page 25 and 26: The premise reveals that the struct
Page 27 and 28: intelligible if it can be referred
Page 29 and 30: elevant consequence of the deductio
Page 31 and 32: Needless to say the plan was to be
Page 33 and 34: and from here that the direction an
Page 35 and 36: since Leonardo 113; the "ad nihilum
Page 37 and 38: But unfortunately for the whole str
Page 39 and 40: The principle of conservation of vi
Page 41 and 42: different from the one joining the
Page 43 and 44: "The equality that exists between e
Page 45 and 46: In virtue of its limitations to New
Page 47: Helmholtz, while asserting that lig
Page 51 and 52: In his search for a mechanical equi
Page 53 and 54: had already been achieved in the Be
Page 55 and 56: approach is discussed at length and
Page 57 and 58: and unaware of Green's results190,
Page 59 and 60: potential function 201. It is worth
Page 61 and 62: and judged unreliable, despite prov
Page 63 and 64: The relevance of the first question
Page 65 and 66: principle taking this potential int
Page 67 and 68: Finally we get to the real conclusi
Page 69 and 70: conservation 234, on the theory of
Page 71 and 72: for the mechanical equivalent of he
Page 73 and 74: The controversy started with some r
Page 75 and 76: where μ are immovable masses, m th
Page 77 and 78: demonstration criticised by Clausiu
Page 79 and 80: directions that join them and whose
Page 81 and 82: quotes 288 and criticises a proposi
Page 83 and 84: motion to all natural forces, the k
Page 85 and 86: measure this expenditure and compar
Page 87 and 88: " ...the quantity of force in natur
Page 89 and 90: forces is constant: but it relates
Page 91 and 92: experiences in general laws of unli
Page 93 and 94: "a series of important and difficul
Page 95 and 96: the Discontinuous Movements of Flui
Page 97 and 98: methodology. Dühring claimed the c
Page 99 and 100:
The first history of the conservati
Page 101 and 102:
while in Britain for the above talk
Page 103 and 104:
apply it to acoustics (1859), hydro
Page 105 and 106:
magnetic intensity. Maxwell realize
Page 107 and 108:
and the electrostatic In modern not
Page 109 and 110:
of conservation of energy: it is re
Page 111 and 112:
efuted. But again in 1881 Helmholtz
Page 113 and 114:
But was important here is that desp
Page 115 and 116:
The second (1892-94), follows the i
Page 117 and 118:
while the electromagnetic and the s
Page 119 and 120:
can modify its specific theoric for
Page 121 and 122:
considered relevant. In Poincarè
Page 123 and 124:
meaning left is: "There is somethin
Page 125 and 126:
interpretations at the beginning of
Page 127 and 128:
while fighting metaphisicians, he w
Page 129 and 130:
literature 456. There is an intrins
Page 131 and 132:
assertion is surprising: it has lon
Page 133 and 134:
Kant was a Naturphilosophe 480. The
Page 135 and 136:
condition that work done by the for
Page 137 and 138:
histories cites these (Hirn's) arti
Page 139 and 140:
) the experimental determinations o
Page 141 and 142:
force principle 522. Elkana tried t
Page 143 and 144:
Blüh, Otto. "The Value of Inspirat
Page 145 and 146:
Graetz, L. "Das Mechanische Wärme
Page 147 and 148:
Helmholtz, Hermann. "Bericht über
Page 149 and 150:
Helmholtz, Hermann. Wissenschaftlic
Page 151 and 152:
Madison: Wisconsin U.P., 1959. Pp.
Page 153 and 154:
Poincarè, Henry. Electricité et O
Page 155:
Yagi, Eri."Clausius's Mathematical
show all

Conservation and Innovation : Helmholtz's Struggle with Energy ...

Create successful ePaper yourself

Delete template?

Save as template?