216 Annals of the Carnegie Museum. 



In order to see some of these lines without the aid of a telescope, I 

 ground a prism of flint glass with a large refracting angle (74°). " 



He then proceeds to state the results of his observations upon 

 sunlight, upon the light of a petroleum lamp, a tallow candle, the flame 

 of alcohol, the electrical spark, and the various metals when subjected 

 to the action of powerful electrical discharges, such as silver, copper, 

 zinc, lead, tin, iron, bismuth, antimony, and brass (an alloy of copper 

 and zinc), and an alloy of copper and silver. 



He describes with minute particularity the appearance of the 

 spectrum and the Frauenhofer lines when the light is affected by the 

 presence of the various substances with which he experimented. 



In Ma}-, 1855, there appeared in the same journal, 2nd Series, Vol. 

 XIX, p. 213, an article the caption of which is as follows: 



" Article XXI. — On Certain Physical Properties of the Light of 

 the Electric Spark with certain Gases, as seen through a Prism, 

 by D. Alter, M.D., Freeport, Pennsylvania." 



In this article he clearly points out the applicability of the method 

 of spectrum analysis to celestial phenomena. He says, "The colors 

 also, observed in the aurora borealis, probably indicate the elements 

 involved in that phenomenon. The prism may also detect the 

 elements in shooting stars, or luminous meteors." Accompanying 

 this article the author sent to Dr. Silliman two daguerreotypes of the 

 dark lines in the solar spectrum which he had made. The art of 

 photography had not advanced beyond daguerreotyping in those days. 



And now it is interesting to know that these articles of Dr. Alter 

 were reproduced in foreign scientific journals in abstract or their 

 entirety. A half page abstract of the first article was published in the 

 Jahrcsbericht der Chemie of Liebig & Kopp for the year 1854, p. 118; 

 the second paper was reproduced in its entirety in L'Institut of Paris 

 in the year 1856, p. 156, and in the Twenty-ninth Volume of the 

 Archives des Sciences Physiques et Naturclles, p. 151, published in 

 Geneva. An annotated abstract of the second article appeared in 

 Liebig & Kopp's Jahrcsbericht der Chemie for the year 1855, p. 107. 

 In the latter special attention is called to Dr. xMter's statement that 

 it is possible by means of the spectrum to distinguish gases as well as 

 metals. 



It was not until the year 1859 that announcement was made of 

 Kirchhoff's discovery that Frauenhofer's lines were due to the presence 

 of various elements in the sun. 



