SOS Scientific Intelligence. 
fact. When Dr Pearson made the Chinese his invaluable pre- 
sent of the vaccine inoculation, it was accompanied by a small 
pamphlet, in Chinese, containing a few necessary directions as to 
the use of the virus, and stating the discovery to have been 
English. A 'purified edition of this little book was very soon after 
published, in which not one word was retained as to its origin, 
nor any trace by which it could be known that the discovery of 
vaccination was otherwise than Chinese. 
83. Cutting of Steel hy Soft /row.— -The very remarkable 
experiment on this subject which we described in our last Num- 
ber, p. 409., has been successfully repeated by Mr Perkins. A 
piece of large hard file was cut by him into deep notches by the 
burr of soft iron. When the burr was applied against the flat 
surface of the file, the teeth were removed without any sensible 
elevation of the temperature of the metal. The burr was not 
reduced in size or weight, but had acquired a very hard surface 
at the cutting part. 
34. Granite for London Bridge. — As this grand national 
work is about to be erected, a considerable discussion has arisen 
respecting the materials of which it is to be built. It is agreed 
on all hands that the stone must be Granite ; and that the gra- 
nite employed must be the strongest in Great Britain. In an 
article in the Journal of the Royal Institution^ Vol. XVI. p. 30. 
it is taken for granted that the Cornish granite is to be used ; 
but the writer of that article, when he made this supposi- 
tion, was certainly not aware of the interesting experiments of 
Mr George Rennie, on the strength of the granite from Aber- 
deen, published in the Philosophical Transactions for 1818, 
p. 131, 132. In that paper, which the anonymous writer quotes, 
Mr Rennie states, that a inch cube of Cornish granite is 
crushed with a force of 14,302 lb. avoirdupois, whereas it re- 
quired 24,556 lb. avoirdupois to crush a similar cube of Aber- 
deen granite. Mr Rennie found also, that the Aberdeen gra- 
nite possessed the valuable property of being lighter than the 
Cornish granite, the specific gravity of the former being 2.625, 
find that of the latter 2.662. Hence it may be shewn, that a pil- 
lar of Cornish granite will crush at its base, if its height is 5498 
feet, whereas a pillar of Aberdeenshire granite will not crush at 
its base till it reaches the enormous height of 9600 feet. In con- 
