It is thought that it may prove of some interest to append the following table, compiled with much care for the British Association, by the author, and printed by that body in their Reports for 1850, and to which now numerous additions are made. It is believed that the dates of discovery are accurately given, the date of publication being, of course, in all cases, taken where there was the slightest doubt :—

In the foregoing chapters every thing has been included which appeared necessary to the complete illustration of the history of Photography. It may be thought by many that the manipulatory details included in this division should have been reserved for that which is more strictly technical. The difficulty of doing this without an annoying repetition, has led me to adopt what I consider to be the clearer course.