694 Chronicles of Science. [ Oct., 
the fragments of old cannon with German wolfram mixed in the same 
proportion, show an augmentation of resistance equal to about sixty-eight 
kilogrammes per square centimetre.* Numerous other experiments 
of a similar character were made, the results appearing to be, in all 
cases favourable to the wolframed pig-iron. There is much difference 
in the character of the tungstate of iron. The French wolfram, con- 
taining a little arsenic and sulphur, is not equal even after roasting to 
the German mineral, which is very pure. 
We noticed in our last Journal Mr. Griffiths’s mechanical puddler. 
Another patent has been obtained by Mr. Thomas Harrison, of the 
Tudhoe Iron Works, Ferry Hill, Durham, for “improvements in 
machinery for puddling iron and steel.” We are not yet aware of any 
works at which this new arrangement has been adopted. The moment 
we learn the result of any trials we will communicate the same to our 
readers. 
VIII. PHYSICS. 
Licnt.—It might be imagined that such an obvious question as that 
of the relative brilliancy of various portions of the solar disc would 
have been definitely settled by this time; yet we find physicists still 
adhering to the opinion that both the centre and the circumference are . 
equally luminous; whilst others, by far the larger majority, adduce 
experiments and reasonings to prove that the centre is considerably 
more luminous than the marginal portions of the disc. Respecting 
the actual light which comes from the sun, we are not aware that any 
accurate photometric experiments have yet been made, although 
observers have long noticed a difference in luminosity between the 
centre and the edge; but we find that the variations of chemical and 
thermic, follow so completely those of luminous intensity, that it will 
be admitted that what is proved of the two former holds equally good 
in the case of the latter. Secchit has shown that the calorific radiation 
of the centre of the sun’s disc is nearly double that from its borders, 
and that the equatorial regions are somewhat hotter than the polar. 
More recently, Roscoe,t in some carefully-conducted experiments, 
showed that the intensity of the chemically-active rays at the centre 
was from three to five times as great as that at the edge of the disc, 
and that the chemical brightness of the south polar regions was con- 
siderably greater than that of the north polar regions, whilst about 
the equator the brightness was between that of the poles. Professor 
Roscoe’s results were obtained by exposing a prepared paper in a 
camera to the action of the sun’s image, and comparing the shade of 
tint produced thereby at the centre and at the circumference with a 
* A kilogramme is the fiftieth part of an English ewt., and a centimetre 
about four-tenths of an English inch. g 
+ ‘Astron. Nachr.’ Nos. 806, 835. 
t ‘Proceedings of the Royal Society, 1863. 
