or of ornamenting Steel with the Prismatic Colours v IS! 
increase in the quantity of reflected light ; and he is, in some 
measure, enabled to judge of the depth, by the faintness of the 
reflected image of his eye, when looking perpendicularly at the 
steel ; until, at last, by totally removing the original surface, in 
consequence of the edges of the cut meeting, the whole surface 
looks black, and the eye is no longer seen. 
Since the preceding notice was written, Mr Barton has had 
the kindness to favour us with various specimens of the orna- 
ments executed by his engine, and high as our expectations 
Were, we confess they were greatly surpassed by the work itself 
Some of the specimens are struck from steel dies, containing 
the grooved pattern, and it is singular to observe the perfection 
with which the impress of such delicate work has been con- 
veyed i 
In one of the patterns on polished steel, a spiral line, begin- 
ning at the centre, advances to the circumference of a circle,' 
about fths of an inch in diameter, each coil of the spiral keep- 
ing at the distance of about g£$th °f an inch from the one ad- 
jacent to it. When the eye, held close to this specimen, views 
a lighted candle reflected from the grooved surface, it appears 
surrounded with a series of the most brilliant concentric rings of 
coloured light, passing into a sort of tinted radiance of exquisite 
beauty. 
When these minute grooves were drawn by Mr Barton upori 
rock-crystal, he was surprised, upon taking it from the engine, 
to perceive no traces whatever of his work. The lines, indeed, 
are so fine, that it is impossible to discover, even by the aid of a 
microscope, any roughness or diminution of polish, although 
its whole surface is covered with grooves, in two directions 
transverse to each other, and at the distance of the 2000th part 
of an inch. The moment, however, we expose it to the sun, or 
the light of a candle, we discover the existence of the grooves, 1 
from the faint prismatic images on each side of the candle. 
We trust that Mr Barton’s ingenuity will be amply rewarded 
by the public taste ; and the only regret we feel is, that he 
should have taken out his patent, before Mr Wrottesley’s bill, 
or some other enactment, shall have secured to inventors, the 
just advantage of their labours, and put an end to that falla- 
i 2 
