R. G. WEST ON LISSAJOUs' CURVES. 41 



the Royal Mint, has shown fine lines ruled on gold, rivalling the 

 diamond in brilliancy of colour. At the International Exhibition 

 of 1862, Mr. Lendy, Engraver to the Royal Mint at Turin, ex- 

 hibited some specimens of reductions on silver and steel effected by 

 a machine which would reproduce, on a scale of xV^h, designs vary- 

 ing in size from 7*87 inches to -039 inch in diameter. As an instance, 

 a coat of arms containing the letter R, surrounded by a Gothic frieze, 

 was engraved on steel in a space -013 inch in diameter. Mr. 

 Webb also showed a reducing machine at the Exhibition of 1862. 

 An account of Mr. Stanistreet's Micro-rulings on glass and steel, and 

 of his instrument for producing them, will be found in the " Monthly 

 Microscopical Journal" for 1871, Vol. vi., pp. 151, 274. 

 In the "Monthly Microscopical Journal" for 1874, mention 

 is made of a Lord's Prayer written by Mr. Webb in a space of 

 ^^th inch x xi r th inch, these measurements being verified by 

 Colonel Woodward. This, it was stated, could be easily read with 

 a good 1 inch objective and central light. 



The only record of the scales of M. Froment, of Paris, that I 

 have met with, names them as ruled to 5I i M inch. M. Froment 

 was celebrated for his microscopic writing, the inspection of which it 

 was that incited Mr. Peters to construct his machine, beautiful and 

 celebrated both in itself and in its results. This machine was des- 

 cribed by Mr. Farrants in the " Transactions of the Microscopical 

 Society" for 1855 (Vol. III. N.S.). Its power of reduction could 

 be varied at will as far as 6,000 times linearly. By its means the 

 beautiful bicircloids of Mr. Perigal were produced in circles the ^th 

 inch in diameter. Among specimens of its performance may be 

 mentioned the inscription of the Lord's Prayer (ending with 

 " deliver us from evil ") in a space -3 g-g-Voo^h sc l nare inch. This is 

 at the rate of over 22 Bibles to the inch. The machine, together 

 with Ibbetson's Geometrical Chuck, was presented by Mr, Peters 

 to the Royal Microscopical Society. A Lord's Prayer is mentioned 

 by Mr. W. Webb, as in the possession of Mr. Frank Crisp, as being 

 written at the rate of over 59 Bibles to the square inch. The average 

 space covered by each letter of this marvellous specimen is said to be 



tne 21 000000 o tn °f a sc l uare inch. 



We now come to the still more wonderful rulings of M. Nobert. 

 With reference to these I would remark that in nothing that I have 

 read about them have I seen mention made of any claim by M. 

 Nobert to absolute uniformity among his various plates ; and I am 



