MEMOIR XIV.] PICTURES OF THE MOON. 213 



After the proof is washed, all the defects in the prep- 

 aration of the plate become apparent. If a film of mer- 

 cury has existed on it, due to its not having been burned 

 sufficiently long, there will be found a want of distinct- 

 ness in the shadows ; or if the plate has not been burn- 

 ed at all, perhaps the former impressions will reappear. 

 This accident frequently happened in my earlier trials, 

 when care had not been taken to give a due exposure 

 each time to the spirit-flame. Spectral appearances of 

 former objects, on different parts of it, emerged an in- 

 terior with Paul Pry coming out, when the camera had 

 been pointed at a church. 



There is no difficulty in procuring impressions of 

 the moon by the daguerreotype beyond that arising 

 from her motion. By the aid of a lens and a heliostat, 

 I caused the moonbeams to converge on a plate, the lens 

 being three inches in diameter. In half an hour a very 

 strong impression was obtained. With another arrange- 

 ment of lenses I obtained a stain nearly an inch in diam- 

 eter, and of the general figure of the moon, in which the 

 places of the dark spots might be indistinctly traced. 



An iodized plate, being exposed for fifteen seconds 

 only close to the flame of a gas-light, was very distinctly 

 stained ; in one minute there was a very strong impres- 

 sion. 



On receiving the image of a gas-light, eight feet dis- 

 tant, in the camera, for half an hour, a good representa- 

 tion was obtained. 



The flame of a gas-lamp was arranged within a magic- 

 lantern, and a portion of the image of a grotesque on 

 one of the slides received on a plate ; a very good repre- 

 sentation was procured. 



With Drummond's light, and the rays from a lime-pea 

 in the oxy-hydrogen blowpipe, the same results were ob- 

 tained. 



