April 22, 1892.] 



SCIENCE. 



237 



this admirable contrivance gives to oae whose problem includes 

 night after night the provision for work in halls of many dimen- 

 sions. But besides having to carry screens of different sizes, the 

 operator needed heretofore tliree or four pairs of objectives of 

 different povvers, a matter of great expense, besides the cumber- 

 some task of packing and unpacking several sets of glasses. 



The multifocal attachment not only dispenses with the burden 

 and exptnse of additional objectives, but also furnishes a picture 

 more nearly perfect than the best combination gives without it, 

 never disturbing the equilibrium of the system of lenses, but 

 adding new powers of definition with entire freedom from dis- 

 tortion of lines and color dispersion. 



This attachment can be furnished in three graded powers to 

 suit different objectives. 



A varying size of picture on the same screen is sometimes de- 

 sirable. When a portrait or statue is to be shown, it might be 

 desirable to have it relatively larger or smaller than the scale 



of the landscape views. To effect this formerly required a 

 change of objectives and an unpleasant interruption ; but with 

 the new attachment the statue may be shown life-size or colossal, 

 and a portrait can be reduced to precisely the best size for life- 

 like presentation. 



The phantasmagoria effect with the Multifocal Attachment 

 is now possible without moving the lantern backward or for- 

 ward. Simply by increasing the distance of the multifocal system, 

 the picture can be reduced to a disc of light of a few inches 

 diameter, and slowly or rapidly enlarged to cover the whole 

 screen. In scientific demonstrations the operator sometimes 

 needs a sharpened pencil of light or a parallel beam. Such 

 wants are readily met by this wonder-working improvement. 

 All workers with the lantern should know about it, as they will 

 appreciate what can be accomplished with it in covering all per- 

 plexities in the distance and size of picture on the screen. 



See advertisement in another column. — Commmi'cated. 



CALENDAR. 

 Biological Society, Washington. 



April 16.— C. W. Stiles, Notes on Para- 

 sites: Tajnia ovilla in its Relation to Blan- 

 chard's Classilication ; F. V. Coville, The 

 Flora of the High Sierras of California. New 

 Plants from California, Nevada, and Utah ; 

 Erwin F. Smith, A Review of Baillon's Bo- 

 tanical Dictionary; J. N. Rose, Mexican 

 Leguminoste with Notes on Dr. Palmer's 

 Collection. 



Society of Natural History, Boston. 



April 20. — John Murray, Some Recent In- 

 vestigations into the Physical and Biological 

 Conditions of the Locks and Fjords of the 

 West of Scotland; E Adams Hartwell. An 

 Elevated Pot-Hole at Fitchburg, Mass ; 

 George H. Harton, Additional Notes on the 

 Drumlins of Massachusetts. 



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