402 Miscellaneous Intelligence, 



14. Achromatic Spectacles. — In our last number we mentioned 

 a very ingenious artificial horizon, executed by Mr. Newman, of 

 Regent-Street, and passed a well-merited eulogy upon his instru- 

 ments in general. We have recently been called upon to examine 

 some achromatic spectacles, which he has constructed especially 

 for the use of the medical department in the West Indies. For 

 persons requiring glasses of from four down to one inch focal 

 length, and such are all who have undergone the operation of 

 couching, these achromatic spectacles are invaluable : not only is all 

 false light gotten rid of, but the extent of field that is gained would 

 not be credited, except by those who have tried them. Where 

 lenses of greater focal length than four inches are employed, the 

 resulting advantage is but trifling. We feel pleasure in noticing 

 this improvement made by a respectable and deserving artist. 



15. Economical process for imitating Silver Paper. — The following 

 Chinese process has been made known in Europe by Pere Du 

 Halde. Take two scruples of gelatine, or Flanders glue, made of 

 ox hide, one scruple of alum, a pint of water. Place the whole over 

 a slow fire until the water is almost entirely evaporated ; spread 

 some sheets of paper upon a table, and with a brush lay on two or 

 three coats of this glue ; then take a powder made of a certain 

 quantity of talc boiled, and one-third of the same quantity of alum. 

 After having well pounded these substances, sift them, then boil 

 them again in water, then dry them in the sun and pound them 

 again. The powder, which is then very fine, is to be passed through 

 a very fine sieve upon the sheets of prepared paper. The talc 

 powder is glued fast ; it is then to be dried in the shade ; after 

 which, remove the superfluous powder with a piece of cotton. — 

 Journal des Connaiss. Usuelles. 



16. On the Magnetic Influence of the Violet Ray, by Professor 

 Zantedeschi, of Pavia. — When Professor Morichini published in 

 1812 his experiments on the magnetic influence of the violet ray, 

 there was no natural philosopher in Europe who did not wish to 

 repeat and vary them ; but, unluckily, the attempts of the most 

 skilful men were not always attended by the success they had a 

 right to expect. Thus it is not surprising that many of the most 

 eminent savans doubted the results of the Italian professor. It 

 was only in 1826 that Mrs. Somerville confirmed, by the most 

 decisive experiments, the fact which he had advanced, that the 

 violet ray possessed a magnetic property. Nevertheless, philoso- 

 phers were not, as yet, satisfied ; they could not verify when they 

 pleased the results obtained, nor discover the causes which impeded 

 the success of their experiments. This state of things led me to 

 undertake a series of experiments on the subject, in this very town, 

 where Professor Configliacchi, in theyear 1813, had already made some 

 remarkable attempts. It was only with great distrust that I under- 



