Miscellanies. 203 



very curious observations on light, made by him from 1840 to the present 

 time, have been credited to Dr. Moser of Konigsberg, and an account given 

 of them by Sir David Brewster, at the last meeting of the British Associa- 

 tion.* Here is part of Dr. Draper's letter. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen — Tf there be a thing in which I have a disinclination to en- 

 gage, it is controversy of a personal kind with scientific fellow laborers. 

 But, as you well know, it ordinarily happens that there is no other gain 

 to philosophers beyond the mere credit of their discoveries, they may be 

 forgiven for reluctantly endeavoring to secure this their only reward. ' 



I have recently returned from a long journey, undertaken for the pur- 

 pose of making trials on the sunlight in lower latitudes, and am grieved 

 to see in the reports that have reached this country of the Proceedings of 

 the British Association, certain announcements, received from Professor 

 Bessel, of phantoms which can be produced on surfaces by mercury va- 

 por, by the breath, and other means, — as though the thing were new. 

 Years ago, if you look into your own Journal, (Feb. 1840, p. 84; Sept. 

 1840, p. 218; Sept. 1841, pp. 198, 199;) you will find that I had pub- 

 lished facts of the kind ; spectral appearances, that could be revived on 

 metals, glass, and other bodies, by the breath, by vapor of camphor, by 

 mercury vapor, &c. The very purpose for which I described them, was 

 the striking resemblance of some of them to Daguerreotope images. I 

 I have repeatedly shown, that by placing a coin or any other object on 

 iodized silver, in the dark, the vapor of mercury will bring out a repre- 

 sentation of it. And in one of the papers just quoted, the condition un- 

 der which camera images can be reproduced on a silver plate, even after 

 the plate has been rubbed with rotten stone, is described. 



I have further seen (Literary Gazette, July 23, 1842, Paris letter) that 

 the fact that light becomes latent in bodies, after the manner of heat, was 

 announced in France as a new and important discovery of Prof. Moser 

 of Konigsberg. In your own Journal, more than a year ago, you printed 

 a long paper written by me on this very topic, (September, 1841, pp. 196, 

 204, 205, 206,) not merely announcing the fact, but giving rude estimates 

 of the amounts : more exact numerical determinations I have now nearly 

 ready for the press.f Yours truly, J. W. Draper. 



University of New York, Sept. 26, 1842. 



* The report of Prof. Moser's alleged discovery, from the Athenaeum, is insert- 

 ed at page 159 of our present number. — Eds. Am. Jour. 



\ Since the above was in type, we have received the December number of the 

 London, Edinburgh and Dublin Philosophical Magazine, and find much new, in- 

 teresting and important matter relative to this subject, from Dr. Draper and Mr. 

 Hunt, (pp. 453, 462;) also in the Athenaeum for Nov. 19, an abstract of Mr. Hunt's 

 paper, and further accounts of Prof. Moser's observations. We hope in our next 

 to give the details of a discovery which promises to be of as much interest as the 

 original observations of Daguerre. — Eds. Am. Jour. 



