HISTORY OF PHOTOGRAPHY.

5

long known to chemists to be possessed by the nitrate of silver, namely,its discolouration when exposed to the violet rays of light.” Fromthis it appears that tho English philosopher had pursued his researchesignorant of what had been done by others on the continent. It is notnecessary to enlarge, in this place, on the merits of the two discoveriesof Talbot and Daguerre ; but it may be as well to show the kind of sen-sitiveness to which Mr. Talbot had arrived at this early period, in hispreparations, which will be best done by a brief extract from his owncommunication.

“ It is so natural,” says this learned inquirer, “ to associate the ideaof labour with great complexity and elaborate detail of execution, thatone is more struck at seeing the thousand florets of an Agrostis dopictedwith all its capillary brancldets, (and so accurately, that none of all thismultitude shall want its little bivalve calyx, requiring to be examinedthrough a lens,) than one is by the picture of the largo and simple leafof an oak or a chesnut But in truth the difficulty is in both cases thesame. The one of these takes no more time to execute than the other;for tho object which would take the most skilful artist days or weeks oflabour to trace or to copy, is effected by the boundless powers of naturalchemistry in the space of a few seconds.” And again, “ to give somemore definite idea of the rapidity of the process, I will state, that aftervarious trials, tho nearest valuation which I could make of the timenecessary for obtaining the picture of an object, so as to have prettydistinct outlines, when I employed tho full sunshine, was half-a-secondThis is to be understood of the paper used by Mr. Talbot for takingcopies of objects by means of the solar microscope.

From this period the progress of Photography has been rapid. SirJohn Ilerscliel has devised many extremely ingenious and useful methodsfor preparing and fixing the drawings; and the curious scientific resultswhich ho has obtained, whilst studying the peculiar functions of thodifferent rays of light, and of the various photographic materials whichhe has employed, are of the highest importance. It were useless toenumerate all who have by their experiments arrived at practical im-provements in tho art; particularly as they will be noticed under thedifferent sections to which their discoveries properly belong. Suffice itthen in this place to state, that the researches of Ponton, Fyfe, Draper,Becquerel, Donne, Soleil, and Bayard, with many others, have alreadyadvanced the art of Photography , and the processes of the Daguerreo-type, to that point, at which their ultimate utility is clearly shown todepend merely on the simplification of their manipulatory details.