450 Messrs . Mouchel on the &fc, 
peated several times, till the plate lias acquired its pro- 
per form and hardness. It is necessary that these plates 
should be of considerable thickness ; and the smallest 
used by Messrs. Mouchel are at least two centimetres 
(.7874$ inches) in thickness. After the wire has under- 
gone the last operation in the workshop of the wire 
drawer, and is reduced to the required degree of fineness, 
the smallest of which is stated at 100,000 metres in 
length to a chiliogram ; or 109*366§ yards to Sib. 3oz. 
5dr. avoirdupois, by means of the bobbin, it is subjected 
to the process of dressage or straightening, which is 
esteemed the most difficult and delicate of all the opera- 
tions. By this it loses the bend or curve it had acquired 
on the bobbins. For the more readily and effectually 
performing this part of the manufacture, these authors 
have also invented apparatus for both straightening the 
wire, and determining its suppleness. But for a parti- 
cular description of these, with other particulars, and a 
table of the prices of the different sorts and sizes of wire, 
we must refer to the Numbers of the Repertory of Arts, 
mentioned at the head of this article, and the plate by 
which the memoir is accompanied. 
Observations by the Editor's of the 'Retrospect* 
Those persons who are either engaged or interested in 
manufactures of this nature, we conceive would be am- 
ply repaid for their trouble of perusing this memoir. It 
will be found to combine a much greater degree of scien- 
tific ingenuity and practical experience than are usually 
met with in similar essays, and the success with which 
these have been exerted may easily be inferred from the 
fineness of the wire produced. From the above state- 
ment it appears that a pound avoirdupois of the smallest 
wire contains about 49*553 yards in length*. Now* ad- 
