As I write on the subject, it appears, of course, necessary that I should be familiar with all the details of manipulation in each process which I may describe. Whenever I have mentioned, in either of my works, a process with which I have not been entirely familiar, I have given the name of the authority upon whom I have depended. But there will not be found in either my _Photography_, or my _Researches on Light_ (of which a greatly enlarged edition will soon be submitted to the public), any one process upon which I have not made such experiments as appeared to me necessary to my understanding the _rationale_ of the chemical changes involved, and of the physical phenomena which arise. Now, since it is not necessary to select a picturesque object to instruct me in these points, the same buildings, trees, and plaster casts have been copied times beyond number; and when the problem under examination has been solved, these pictures have been destroyed. There are twenty exhibitors of pictures in the Photographic Gallery who would certainly leave my productions far behind, as it concerns their pictorial character; but I am confident there is not one who has made the philosophy of Photography so entirely his study as I have done. I have been engaged for the last two years in studying the chemical action of the prismatic spectrum. I inclose you my report on this subject to the British Association for 1852 (that for 1853 is now in the hands of the printer), from which you will perceive that I am employing myself to greater advantage to photography, as science under art, than I should be did I enter the lists with those who catch the beauties of external nature on their sensitive tablets, and secure for themselves and others pictures drawn by the solar pencil, in which no one can more deeply delight than your humble servant. ROBERT HUNT. _Waxed-paper Pictures._--Will your correspondents or yourself do me the favour to say, how such beautiful pictures have been produced and exhibited by Mr. Fenton and others by the waxed-paper medium, if that process be so bad and defective? When I have followed it, and exercised consistent patience, I have ever produced pleasing and faithful results. That when parties do not themselves prepare, it becomes expensive, I am willing to admit; but I am inclined to attribute many failures to the uncertain heat of hot irons, which _must_ vary; and I make this fact known to you as the result of my own observation on many sheets: added to which, defective manipulation, or impure chemicals, must not be allowed to do away with its having much merit. HARLEY LANE.