records of bygone times, the occupations of mankind, even in their 

 leisure hours, was a pursuit worthy of being undertaken upon 

 scientific principles, as affording many valuable hints to the 

 anthropological observer ; and for that reason he had brought thp 

 subject before the Lewisham and Blackheath Scientific Association. , 



TUESDAY, MARCH 2nd. 



.J. Weege, Esq., gave a Lecture on ''Photography : its Origin. 

 Progress, and Practice." 



After mentioning at some length the various unsuccessful 

 attempts by Wedgwood, Sir Humphrey Davy, Niepce, and others. 

 Mr. Werge described some of the experiments of Louis Daguerre. 

 who, after toiling in the most persevering manner for fifteen years, 

 at last succeeded, not only in depicting a picture on a plate of silver, 

 but in fixing it in a tolerably permanent manner. His discover)' 

 was made public in 1839. At about the same time Mr. Fox Talbot, 

 who had also been engaged for several years in similar investigations, 

 announced his discovery of a method of photographing on paper, and 

 fixing the picture so that it could bear subsequent exposure to light. 



By the method of Daguerre. only one picture could be produced : 

 while by that of Talbot, any number could be pi'inted off expeditiously 

 and cheaply. As a consequence, the method of Daguerre fell into 

 disuse, although the pictures were sometimes very beautiful indeed. 

 His process is, roughly, as follows : — A highly-polished plate of 

 silver is subjected to the vapour- of iodine, until an iodide of silver 

 is formed on its surface. The plate, now highly sensitive to the 

 action of the light, is next placed in the camera, and the pictui'e is 

 taken. The plate is then exposed to the vapour of mercury, which 

 attacks all those parts that have been affected by the light, leaving 

 untouched the unaffected portions. The pictui'e is now perfect, but 

 it will not yet bear exposure to light, for there is still some sensitive 

 iodide of silver on the plate. This is readily removed by means of 

 a solution of hyposulphite of soda, into which the picture is dipped. 

 The iodide of silver is washed off, and no further change ensues by 

 the action of light. 



