I04 



THE POPULAR SCIENCE MONTHLY 



troleum. The plate was exposed for 

 several hours, the image etched, and 

 then prints were made as from an ordi- 

 nary etching. The museum colleetiou 

 includes one of the first permanent 

 photographs printed from a light etched 

 plate by the heliographic process. This 

 print is from Niepce's plate made -in 

 ]824. 



There are also several fine examples 

 of Daguerre's work made in 1839 and 

 later. His process, •vhich came to be 

 known as the Daguerren^ype process, 

 consisted of exposing a highly polished 

 silvered copper plate, fumed with io- 

 dine, in a camera a few minutes, de- 

 veloping the exposed plate with mer- 

 C'lry vapor and fixing the image with 

 liypo-snlphite. This complex "process 

 'nvolved five distinct operations; clean- 

 ing and polishing the plate, coating the 

 plate with sensitive ioduret of silver, 

 adiusting and exposing the plate m 

 the camera cbscura, developing the in- 

 visible picture after the exposure, and 

 removing the -n sitive coating so that 

 no further ch: ge would take place in 

 the picture. Daguerre and Niepce 

 found that they were pursuing experi- 

 ments of the same nature and went 

 into partnership. 



Six months prior to M. Daguerre's 

 publications concerning his process, Mr. 

 Fox Talbot communicated his photo- 

 graphic discoveries to the Eoyal So- 

 ciety, and afterwards issued an ac- 

 count of his scheme for preparing a 

 sensitive paper for photographic re- 

 production which he called photogenic 

 drawings. He prepared his paper by 

 washing a sheet of fine writing paper 

 with solutions of salt and silver nitrate. 

 When dried this proved of use in secur- 

 ing prints of leaves, etc., in the camera 

 obscura.. Later he used iodide of po- 

 tassium and other chemicals to perfect 

 his system. Talbot's second process of 

 paper making was patented in 1841, 

 and was known as the calotype. The 

 main advance in this system was the 

 ability of the discoverer to make un- 

 limited prints of his picture. Talbot 

 obtained a third photographic patent 



on a process for photographing on un- 

 glazed porcelain, which a man by the 

 name of Alalone improved somewhat 

 and eventually became associated with 

 Mr. Talbot. 



The museum collection, besides in- 

 cluding many fine and unique examples 

 of these first photographic processes, 

 has much material on modern practical 

 photography, including examples of dif- 

 ferent printing papers, and plates, 

 stereoscopic pictures, flash-light para- 

 phernalia, X-ray and colored photo- 

 giaphs, astrophysical photographs and 

 some early examples of moving picture 

 making. 



SCIENTIFIC ITEMS 



We record with regret the death of 

 Charles Sedgwick Minot, James Still- 

 man professor of comparative anatomy 

 in the Harvard Medical School, eminent 

 for his contributions to embryology 

 and biology and for public services 'n 

 science; of Dr. Theodore Lipps, pro- 

 fessor of psychology and philosophy of 

 the University of Munich, and of Dr. 

 Rudolf Emmerich, professor of hygiene 

 and bacteriology in the University of 

 Munich. 



The Hayden gold medal of the Phila- 

 delphia Academy of National Sciences 

 has been presented to Dr. Henry Fair- 

 field Osborn, in recognition of his pale- 

 ontological studies. — The De Morgan 

 medal of the LfOndon Mathematical So- 

 ciety has been given to Sir Joseph 

 Larmor in recognition of his re- 

 searches in mathematical physics — One 

 of the royal gold medals of the Eoyal 

 Society, has been awarded to Professor 

 Ernest Willliam Brown, of Yale Uni- 

 versity, in recognition of his investiga- 

 tions in mathematical astronomy 



Dr. Allen J. McLaughlin, formerly 

 of the Public Health Service, has as- 

 sumed the duties of health commis- 

 sioner of Massachusetts. — Dr. C.-E. A. 

 Winslow has resigned from the College 

 of the City of New York to become di- 

 rector of education in the reorganized 

 State Department of Health. 



