Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art . ppeared in the British Journal of Photography someyears ago (Fig. 238). Practicallyit consists of a square box sodivided as to represent any de-sired number of square tubes—nine, of two inches square andthree inches deep, should an-swer admirably, and would as-sume the form of a box 6x6x3inches. One side of the box, or oneend of the tubes, is fitted so asto receive a plate holder or darkslide, in which the plate isplaced, and the other side, orend of the tubes,
Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art . ppeared in the British Journal of Photography someyears ago (Fig. 238). Practicallyit consists of a square box sodivided as to represent any de-sired number of square tubes—nine, of two inches square andthree inches deep, should an-swer admirably, and would as-sume the form of a box 6x6x3inches. One side of the box, or oneend of the tubes, is fitted so asto receive a plate holder or darkslide, in which the plate isplaced, and the other side, orend of the tubes, is covered bya metallic plate in which aredrilled nine holes, each in thecentre of one of the square tubes,and each exactly twice the valuein light-admitting area of itspredecessor. The size of the openings, distance of the flash from the plate, and quantityof magnesium flashed, could easily be arranged, so that the nine numbers would includeplates from the slowest to the most rapid in use at present; and while a sensitometer thusarranged might not be altogether perfect, it certainly would approximate more nearly to Fig. 238 Wilsons quarter century in photography. Keep on the alert for these chances—draw on your fund of knowledge tuhelp you when they are presented, then your results will surely do you credit. perfection, and convey a more correct knowledge of the true sensitiveness of a plate thanany form of instrument that has as yet been proposed.—Dr. John Nicol. My photometer is a simple prism made of yellow glass (Fig. 239, side view), framed insuch a manner as to become an ornament for a watch chain. Upon the inner surface ofthis yellow glass prism lines are drawn beginning from 1 to 10; No. 1 represents thefinest part of the prism, and No. 10 the thickest. A piece of sensitized paper is intro- FiQ. 239. Fio. 2-iO.
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Keywords: ., bookcentury1800, bookdecade1880, bookidwilsonsquart, bookyear1887
