1297 
in this communication some positive results showing the non-existence 
of a heat-resistance, even if deviations from Hooke’s law appear. 
We shall confine ourselves to the linear problem, so that it still 
remains uncertain whether our conclusion holds really for three 
dimensions. This forces us to enter still into some principal errors 
in DrBijk’s calculation, which cause his results to be not only merely 
qualitative, but quite illusory in our opinion, so that they are no 
argument against the mentioned extension of our conclusion. 
In consequence of his calculations on the linear problem, 
SCHRÖDINGER!) has doubted of the conduction of heat being infinitely 
great in the ideal case. Let us therefore in the first place mention 
a simple proof for this case. 
Let w denote the place of a point on the bar in condition of rest, 
vhs the same after deformation. According to Hooxnr’s law 
s 
ò 
the stress would become proportional to a As a next approxima- 
v 
0§ 0 
tion we shall now put this proportional to see (=) The 
av 
equation of motion now becomes: 
Oe ORE DE SORE 
ee eas a ee = Chaise e a . . 1 
of?" On? a Ox 02? (1) 
if for the moment we take unimportant coefficients — 1. 
If we represent for the sake of brevity the differential coefficients 
of § by § and §&, the energy per unit of length is: 
- a 
&=& + & = 45? +4" migen 
In unit of time the tension of the bar performs in the point a 
a work 
or, ee 12 
sl: + 5 s ). 
Now if a current of energy goes through the bar (conduction of heat) 
the time-average of this expression must differ from zero. Now we 
will examine whether a fall of temperature appears along the bar. 
For this purpose we calculate: 
de — 
—_ fe BEE BIE Ve sheen 
Oe are T 9 ahi 
Applying the equation of motion we oa 
de eef ser sent a grec foun 
onse eh eer: LE Se 
We shall take the time average of the last form for a stationary 
1) Ann. de Physik. 42. 1914 p. 916. 
