_Stereoscopic Angles_ (Vol. viii., pp. 109. 157.).--I perfectly agree with your correspondent MR. T. L. MERRITT (p. 109.) respecting "stereoscopic angles," having arrived at the same conclusion some months since, while at Hastings, where I produced stereoscopic pictures by moving the camera _only two inches_: having in one, _seven_ houses and _five_ bathing-machines; and in the other, _five_ houses and _eight_ bathing-machines. If I had separated the two pictures more, I should have had _all bathing-machines_ in one and _all houses_ in the other; which convinced me that nothing more is required than the width of the two eyes for all distances, or, slightly to exaggerate it, to three inches, which will produce a pleasing and natural effect: for it is quite certain that our eyes do not become wider apart as we recede from an object, and that the intention is to give a true representation of nature as seen by one person. Now, most stereoscopic pictures represent nature as it never could be seen by any one person, from the same point of view; and I feel confident that all photographers, who condescend to make stereoscopic pictures, will arrive at the same conclusion before the end of this season. If this be correct, all difficulty is removed; for it is always advisable to take two pictures of the same prospect, in case one should not be good: and two very indifferent negatives will combine into one very good positive, when viewed by the stereoscope: thus proving the old saying, that two negatives make an affirmative. HENRY WILKINSON. Brompton. _Sisson's Developing Solution._--In answer to S. B.'s inquiry, I beg to say, that I have not tried the above solution as a bath. I have always poured it on, believing that it was easier to observe the progress of the picture by that mode. If S. B. will forward me his address, I shall be happy to enter more minutely into my mode of operating with it than I can through the medium of "N. & Q." I have received other favourable testimony as to the value of my developing fluid for glass positives.