ISO Mr Barton's Method of making the Iris Metal ornaments , 
in an inch* Mr Barton often leaves out one line intentionally; and 
one of the greatest proofs of the stability of the engine is, that 
after having taken off the brass table, with the work upon it, 
(when the omission is distinctly perceived), he can restore it to 
its place , and introduce the line , without its being distinguish- 
able from the rest. 
In applying the principle of striated colours to ornament 
steel, the effect or pattern is produced upon the polished surface, 
bv the point of a diamond, so that either the whole, or a part 
of the surface, is covered with lines or grooves, whose distance 
may vary from the 1000th to the 10,000th of an inch. When 
these lines are most distant , the prismatic images of the candle, 
or any luminous body, seen by reflection from the polished sur- 
face, are nearest one another and the common colourless image ; 
and when the lines are least distant , the coloured images are 
farthest from one another, and the colours are most vivid. 
In day-light, the colours produced by these minute grooves 
are scarcely distinguishable, unless at the boundary between a 
dark and a luminous object; and we conceive that their bril- 
liancy will be very much impaired, even with artificial lights, 
when they are dispersed by the interposition of globes or he- 
mispheres of ground glass. 
In sharp lights, however, and particularly in that of the sun, 
the colours shine with extraordinary brilliancy, and the play of 
tints which accompany every luminous image, can only be- 
equalled by their matchless exhibition in the reflections of the 
diamond. The surface of fine steel, therefore, when grooved by 
such a skilful hand as Mr Barton’s, is peculiarly fitted for imi- 
tative jewels, and other articles of female dress ; and we have no 
doubt, that it will find an application to many other purposes, 
both of use and ornament. 
The divisions which Mr Barton most commonly uses for his 
metal ornaments are 2000 to an inch ; but when the material is 
good, his engine enables him to divide to 5000 and 10,000. 
When the lines, however, are so close, the labour is very great ; 
but the beauty of the work is generally a compensation for the 
time bestowed upon it, as the strength of the colours increases 
with the number of lines. The depth of the line, Mr Barton 
finds to have a great effect in producing brilliancy, owing to the 
