155 



A letter from Mr. Hector Orr was read, describing a new 

 and ingenious microscope-slide, devised and exhibited before 

 the Franklin Institute by its Curator Mr. D. S. Holman, at a 

 meeting of its Optical Section. 



Donations for the Library were received from the Russian 

 Geographical Society ; Bavarian and Belgian Academies ; 

 the Societies at Wiesbaden, Frankfort and Geneva; Revue 

 Politique and Dr. Girard, of Paris ; the Meteorological Office, 

 Society of Arts, and Prof. Owen, of London; the Naval 

 Observatory of San Fernando; the Mass. Board of R. R. 

 Commissioners ; Ed. M. Stone, of Providence ; American 

 Journal of Science and Prof. Dana, of New Haven ; the Phil. 

 Journal of Pharmacy, Dr. Kirkbride and Prof. Cope ; the 

 Board of Public Charities of Pennsylvania; and the Bureau 

 of Education at Washington. 



The death of Dr. Hugh L. Hodge, of Philadelphia, Feb. 

 26th, aged 77, was announced by Prof. Cresson, and, on 

 motion made, Dr. Penrose was appointed to prepare an 

 obituary notice of the deceased. 



The death of Dr. Thos. McEuen, of Philadelphia, Feb. 

 27th, aged 73, was announced by Prof. Cresson. 



Dr. Seiler was invited to exhibit before the meeting two 

 Magic Lantern Slides for producing on the screen the 

 alternately vibrating waves of light, one of which he had 

 made in imitation of the apparatus used for that purpose 

 in his recent lectures by Prof. Tyndall, consisting of con- 

 centric ellipses on a revolving disc ; the other he had devised 

 and constructed as an easier and simpler form which any 

 one could make, viz., a long slide on which diverging and 

 converging lines replace the ellipses. A medial horizontal 

 straight line gives a constant central point of light, to and 

 from which vibrating points are produced by the diverging 

 and convero-mo; straight lines above and below the medial 

 line. 



The Secretary exhibited a large Map of the Underground 

 Workings of the Collieries south ot Wilksbarre, in the Third 

 Anthracite Coal Basin of Pennsylvania, surveyed and drawn 



