222 Miscellaneous Intelligence. 
the quadrant of ninety degrees, it may be let fall upon the steel 
anvil which is attached to the small table upon which the 
whole is fixed. 
In using this instrument, the different kinds of lead are cast 
into bullets of twenty-six to the pound, having a diameter of 
four-tenths of an inch ; these are carefully smoothed and placed 
in the centre of the anvil, upon the surface of which are engraved 
several concentric circles; the hammer is then elevated to. 50°, 
and let fall upon the ball under examination, which becomes 
flattened by the successive blows into a disc of 1.2 inches dia- 
meter. The number of blows given to each ball, in order to 
produce this extension, are counted. The following table shows 
the results of some of these trials : 
Samples. Number of Blows. 
1 Old sheet lead = 2 < y - yh Te 
2 New lead in pigs (W. Blackett) SThian, qisaget 
3 Ditto (Blangill) = = = tt 
4 Ditto (Caldebek) Lah - 12 
5 Newsheet lead = - - - = ° - 12 
6 Old lead of tenfusions§ - . - - - 10 
7 Cuttings of lead - = (fk - - Serene. 
8 Lead, with one-tenth of zine - - ae ek 
9 Tin - - - = - = - - 40 
It appears that lead, ten times re-melted, instead of being in- 
jured, is improved in quality; that lead mixed with one-tenth of 
zinc is very sensibly hardened, and that the hardness of the best 
English tin is to that of the softest lead as four to one. 
5. On the Application of Machinery to the purpose of calcu- 
lating and printing Mathematical Tables.—A letter from Mr. 
Babbage to Sir H. Davy, has appeared under the above title. As 
we have not seen the machines adverted to, we must rest con- 
tent with giving the following extract describing their powers 
and properties, for, of their construction, nothing has as yet 
transpired. 
The first engine of which drawings were made was one which is capable 
of computing any table by the aid of differences, whether they are positive 
or negative, or of both kinds. With respect to the number of the order of 
differences, the nature of the machinery did not in my own opinion, nor in 
that of a skilful mechanic whom I consulted, appear to be restricted to any 
very limited number ; and I should venture to construct one with ten or a 
dozen orders with perfect confidence. One remarkable property of this 
machine is, that the greater the number of differences the more the engine 
will outstrip the most rapid calculator. 
By the application of certain parts of no great degree of complexity, 
this may be converted into amachine for extracting the roots of equations, 
and consequently the roots of numbers: and the extent of the approxima- 
tion depends on the magnitude of the machine. 
Of a machine for multiplying any number of figures (m) by any other 
number (n) I have several sketches; but it is not yet brought to that 
degree of perfection which I should wish to give it before it is to be 
executed, 
