Nearly all the denominations of photography have their representative forms and impressions in this Exhibition; and the history of the art, from the early days of the Daguerreotype to the latest vagary of the present day, may be traced in the collection of photographs spread before you on the walls and screens of the Dublin International Exhibition. There is the Daguerreotype, the Ambrotype, and the collodiotype, which ought to have been known as the Archertype; for the wet collodion process, although it is the most important of all the discoveries in photography that have been made since the first pictures were obtained by Wedgwood, is without a name conferring honour on the man who first applied collodion to photography. Archer's name is generally associated with it, but without taking that definite and appellative form it ought to. We know that another claimant has been "cutting in" for the honour, but unless that claim can be "backed up" by data, we are not disposed to believe that it was anterior to 1851--the year of the first exhibition; at that date we know that Mr. Archer took photographs on collodionized glass plates. Then why should we not honour Archer as the French honoured Daguerre, and call the wet collodion process the Archertype? In printing and toning, there are samples of nearly all the formulæ that have been discovered since the days of printing on plain salted paper and fixing in "hypo" only. There are prints on plain paper and on albumenized paper, toned and fixed in every conceivable way. There are prints on glass, porcelain, and ivory; prints in carbon, from the negative direct; and impressions in printer's ink from plates, blocks, and lithographic stones, which have had the subjects transferred to them by the aid of photography. There are Wothlytypes, and Simpsontypes, and Tooveytypes, and all the other types that have sprung from a desire to introduce novelties into the art. In graphs and the various forms and fanciful applications of photography to portraiture, &c., there are stereographs and micrographs, and the old-fashioned "sit-on-a-chair" graphs, the "stand-not-at-ease" graphs, the "small carte" graph, the "large carte" graph, the "casket gem" graph, the "magnesium" graph, the "cameo" graph, the "double-stupid" graph, and the latest of all novelties, the "turn-me-round" graph. The latter is a great curiosity, and must have been suggested by a recollection of that "scientific toy" of ancient manufacture with which we used to awaken the wonder of our little brothers and sisters at Christmas parties when we were boys, by twirling before their astonished eyes a piece of cardboard with a bird painted on one side and a cage on the other, both pictures being seen at the same time during the rapid revolution of the card.