The Roman Astronomers state that they have procured Daguerreotype impressions of the Nebula of the sword of Orion. Signor Rondini has a secret method of receiving photographic images on lithographic stone; on such a prepared stone they have succeeded in impressing an image of the Nebula and its stars; "and from that stone they have been enabled to take impressions on paper, unlimited in number, of singular beauty, and of perfect precision." Experiments have, however, proved that "no heating power exists in the moon's rays, and that lunar light will not act chemically upon the iduret of silver."

It was at one time supposed that terrestrial or artificial light possessed no chemical rays, but this is incorrect--Mr. Brande discovered that although the concentrated light of the moon, or the light even of olefiant gas, however intense, had no effect on chloride of silver, or on a mixture of chloride and hydrogen, yet the light emitted by electerized charcoal blackens the salt. At the Royal Polytechnic Institution pictures have been taken by means of sensitive paper acted upon by the Drummond Light; but it must of course be distinctly understood, that they are inferior to those taken by the light of the sun, or diffused daylight.

If our operators could manage to produce good pictures in this way they would put money in their pockets, as many who cannot find time during the day would resort to their rooms at night. I throw out the hint in hopes some one will make the experiment.

I have learned, since the above was written, that an operator in Boston succeeded a short time since in procuring very good pictures by the aid of the Drummond Light; but that the intensity of the light falling directly upon the sitter's face caused great difficulty, and he abandoned it. This may, probably, be remedied by interposing a screen of very thin tissue paper tinged slightly of a bluish color.