459 
of Edinburgh, Session 1870 - 71 . 
Coloured glasses lose their colour in the fire. 
Kirchhoff, Oct. 1859.—Introduction of reasoning more directly 
based on the Second Law of Thermodynamics. 
Proof that the absorbing flame must be colder than the 
source—Exception for Fluorescence. 
Kirchhoff and Stewart.—Tourmaline, which polarises common light 
by absorbing polarised light, gives off, when hot, polarised 
light like that which it absorbs. 
© 
(Note that the discussion of the question of priority on this subject, in 
papers by Stokes, Thomson, Kirchhoff, and Stewart, in the Phil. Mag. 
1863, is very interesting, and may still be read with profit). 
Fluorescence is Degradation of Energy. 
Exhibit Stokes’ fundamental Experiments. 
The question of priority just alluded to illustrates in a very 
curious way a singular and lamentable, though in one sense 
honourable, characteristic of many of the highest class of British 
scientific men; i.e., their proneness to consider that what appears 
evident to them cannot but be known to others. I do not think 
that this can be called modesty; it is rather a species of diffidence 
due to their consciousness that in general their accurate knowledge 
of the published developments of science is confined mainly to 
those branches to which they have specially devoted themselves. 
Their foreign competitors, on the other hand (especially the 
Germans), are often profoundly aware of all that has been done, 
or, at least, have some one at hand who is, and can thus, when 
a new idea occurs to them, at once recognise, or have determined 
for them, its novelty, and so instantly put it in type and secure it. 
Neither Stokes nor Thomson, in 1850, seems to have had the least- 
idea that he had hit on anything new, especially as they had a 
vague recollection that Foucault had previously attacked the pro¬ 
blem—the matter appeared so simple and obvious to them—and, 
but for the fact that Thomson has given it in his public lectures 
ever since (at first giving it as something well known), they might 
have thus forfeited all claim to mention in connection with the 
discovery. I could mention many other striking instances of this 
peculiarity; one, in fact, appeared in our own Proceedings a 
few months ago; but to consider it more closely would lead me 
away from the subject of my lecture. It is sufficient to have 
called attention to a want which could easily be supplied, if we 
