J. E. Loughlin on Fluorescence. 239 
Prince Patrick’s Island, tell the same story of the former exist 
ence of something like a subtropical climate at places at present 
well within the arctic circle. 
To use the words of the Rev. Samuel Haughton,* in describ- 
ing the fossils collected by Sir F. L. McClintock, “The discoy- 
ery of such fossils in situ, in 76° N. latitude, is calculated to 
throw considerable doubt upon the theories of climate, which 
would account for all past changes of temperature by changes 
in the relative position of land and water on the earth’s surface ;” 
and I think that all geologists will agree with this remark, and 
feel that if the possibility of a change in the position of the 
axis of rotation of the crust of the earth were once admitted, 
it would smooth over many difficulties they now encounter. 
That some such change is indeed taking place at the present 
moment may not unreasonably be inferred from the observations 
of the Astronomer Royal, who, in his Report to the Board of 
Visitors for 1861, makes use of the following language, though 
“only for the sake of embodying his description of the observed 
facts,” as he refers the discrepancies noticed to “some peculiari 
of the instrument... . . The transit circle and collimators still 
present those appearances of agreement between themselves and 
of change with respect to the stars which seem explicable only 
On one of two suppositions—that the ground itself shifts with 
respect to the general earth, or that the axis of rotation changes 
fe 
its positio 
Arr. XXVIII—On Fluorescence; by J. ENru LovGHiiy, 
; Philadelphia. 
In the year 1845, Sir J. Herschel published two papers in the 
Philosophical Transactions,’ on what he termed the epipolic 
dispersion of light. His researches were made upon sulphate 
of quinia and other organic substances, from which researches 
he deduced the conclusion that the colors came from the surface 
of the liquid at which the light entered, and that a ray of light 
having once passed through such a stratum has lost the power of 
reproducing the same effect. Sir D. Brewster, in 1846, in a 
Paper read before the Royal Society of Edinburgh, drew atten- 
tion to a similar phenomenon in a solution of the green principle 
of leaves, and disproved the ideas of Sir J. Herschel, by show- 
ing that the light was dispersed not merely at the surface, but 
for a long distance within the fluid. In 1852, the subject was 
taken up by Mr. Stokes of Cambridge, and by him ably dis- 
cussed. He examined many organic substances and arrived at 
* Journal of the Royal Dublin Society, vol. i, p. 244. 
t 
