Trans. A\ V. Ac. Set. 180 June 5, 



The great advantage of the process for all these purposes is to be 

 found in the sensitive plates. They can be purchased ready for use in 

 the camera, and will remain good for any length of time. They may 

 be carried across the continent, exposed in a camera on the top of a 

 mountain hundreds of miles from civilization, or in the interior of an 

 unexplored country, then packed away in light, tight boxes, and the 

 pictures developed months afterward in this city. In this way the 

 geological and topographical features of a country may be accurately 

 reproduced on paper, or, by means of glass positives, thrown upon a 

 screen for the illustration of a lecture. The botanist may photograph 

 a rare plant in bloom in distant lands, and the traveller in Central 

 Africa, for instance, may portray the features of the natives he finds, 

 with far more truthfulness than with pencil and brush. 



In the laboratory, the student of physics will find many uses for 

 photography. Already, it has been applied to the study of spectra, 

 with great advantage, and lately the electric spark has been photo- 

 graphed, with an exposure, it is said, of only TjuVoxr of a second. 



[The method of making instantaneous pictures was then described, 

 and the apparatus was exhibited. After the Academy adjourned, the 

 process of making positives on glass for use in a lantern was illustra- 

 ted by placing a negative over a sensitized plate in a deep printing- 

 frame, and exposing it to the Hght of an argand lamp for about ten 

 seconds, after which the picture was developed and fixed in the usual 

 way.] 



June 5, 1882. 



Regular Business Meeting. 

 The President, Dr. J. S. Newberry, in the Chair. 

 Forty-five persons present. 

 The report of the Council was read, recommending 



1. The election of the following persons, previously nominated 

 as Resident Members : 



J. K. Funk, W. H. Mead, 



Howard Wainwright, Alexander Warner. 



2. That when the Academy adjourns, it shall be to October 2. 



The four persons named were unanimously elected, and the re- 

 commendation for the usual summer adjournment was agreed to. 



The President showed teeth of Carckarodon, measuring five 

 inches by six, from the tertiary " Phosphate beds" of South Caro- 

 lina. This is about the maximum size ever known for fossil shark- 



