or of ornamenting Steel with the Prismatic Colours. 129 
Surface was unpolished, and that they could be communicated 
to wax, gum-arabic, tinfoil, the fusible metal, and even to lead, 
by hard pressure, or the blow of a hammer. He determined 
also, that the mottled colours upon all bodies with an imperfect 
polish, and the scratches or grooves Upon polished metals, could 
be communicated to wax , and other substances * 
The same structure which gives these communicable colours, 
he succeeded in producing artificially on the surface of calves- 
feet jelly, that had been boiled for a considerable time. This 
surface was covered with corrugations; but totally unconnected 
with these corrugations, he discovered, with a powerful micros- 
cope, the same minute grooves which exist in mother-of-pearl, 
and they were so near one another, that some thousands of them 
must have been contained in a single inch. These grooves 
were completely invisible to the unassisted eye, but they gave 
in a very distinct manner, the colours of mother of-pearl. 
Mr Barton, of the Mint, a gentleman well known for his in- 
genuity and his mechanical attainments, has recently conceived 
the happy idea of ornamenting steel, and other articles, with 
the colours of striated surfaces, and has secured, by patent, the 
exclusive privilege of applying this principle to practical pur- 
poses. The excellence of Mr Barton's engine has, no doubt, 
enabled him to execute this kind of work, with a beauty and 
precision which no other person can hope to imitate. The engine 
which he uses was given to him by his father-in-law, the late ce- 
lebrated Mr Harrison. It was constructed by Mr Harrison 
himself, and its merits depend chiefly on the beauty and correct- 
ness of the screw; the apparatus for cutting which, by an ex-* 
cellent inclined plane, also accompanied the engine. The plate 
in the screw is not divided higher than the SOOOdth part of an 
inch ; but Mr Barton has drawn divisions on steel and glass so mi- 
nute as the 10,000dth part of an inch. In drawing lines of 2000 
* Dr Brewster also succeeded in communicating the colours from one piece of wax 
to another piece of wax , and from this second piece to a third piece. By a little 
precaution, a sunk impression may, upon the same principle, be taken from a wax 
seal, upon another piece of wax ; and this may be used, for a long time, to give 
impressions nearly as distinct as the original seal.* If the piece of wax to be used 
is hardened with lac, it will last still longer. 
VOL. VIII. NO. 15. JANUARY 1823. 
I 
