ELECTRICAL STANDARDS. 155 
carried out. I therefore regard your proposition as a welcome oppor- 
tunity for going into the neglected question, and I may say that I am 
determined to recalculate, in the forthcoming third edition of my text- 
book, the whole of the thermo-chemical data in such a manner as to do 
my utmost to diminish the difficulties consequent on the transition. I 
have already (in 1891) expressed my opinion very clearly, and I now send 
you the memoir referring to it.! 
I differ from your proposals, however, as regards the magnitude of 
the unit to be adopted. I believe that only an erg multiplied by some 
integral power of 10 should be chosen. I formerly proposed a Mega-erg, 
but have now altered my opinion. 
_ As apractical multiple of the erg, we already possess one in electricity, 
viz., the Joule = 10’ ergs ; and it appears to me to have the great 
advantage that the practical unit of energy in constant use in the 
two great departments of electrical and thermal measurements would be 
identical ; therefore I do not think that any other choice could be so 
advantageous. 
4.—From Dr. F. Paschen, Tit. Professor of Physics, Hanover, 
November 24, 1895. 
. . . We must have an absolute unit simply related to other absolute 
units, and that would be your ‘ Rowland’ ; but we must also know how 
to realise this unit. For this purpose the specific heat of water must be 
fixed for each temperature. 
I think, as the different observations on the variability of the specific 
heat of water differ so greatly, your statement III. (p. 3) is a very 
preliminary one. . . . I think it would be best to propose that a new 
determination of the changes in the specific heat of water should be 
undertaken by some institute that has the necessary apparatus and 
money. 
5.—From Dr. M. Planck, Professor of Physics, Berlin, 
November 25, 1895. 
[ TRANSLATION. ] 
If I may venture on giving my opinion on the propositions made by 
you, I must emphasise, before all things, that I agree with you as to the 
necessity of having a well-defined universal unit of heat, and I should be 
very glad if your well-considered plans led to a definite result. As a 
theorist [ would make even more radical demands as to the unit to be 
defined. The ideal universal unit of heat appears to me to be still more 
closely related to the definition of the electrical units ; consequently I 
would define :— 
I. One ‘ Rowland’ (or ‘ Meyer,’ or ‘ Kelvin’) as that quantity of heat 
which is equivalent to 10% ergs. 
II. According to the best measurements hitherto obtained 1 ‘Row- 
land’ is that quantity of heat which raises 1 gramme of water at 15° C. 
through 2°39 C. It would be possible to modify this number in the 
light of subsequent experiments. We should thus avoid the arbitrary 
character involved in the choice of such numbers as 41:89 x 10° or 42 x 10°. 
1 See Studien zur Energetik, p. 577. 
