It was in September, 1839.

The time, if I recollect, in which the plate was exposed to the action of light in the camera was about fifteen minutes.

The instruments, chemicals, etc., were strictly in accordance with the directions in Daguerre's first book.
"An English gentleman, whose name at present escapes me, obtained a copy of Daguerre's book about the same time with myself.

He commenced experimenting also.

But an American of the name of Walcott was very successful with a modification of Daguerre's apparatus, substituting a metallic reflector for the lens.