Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art . 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
Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art . 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. duced under the prism and allowed to remain one minute (in the shade it is thenexamined), and according to the number that the impression has reached, it is very easyto calculate the photogenic power of the light. In order to give my readers a correct idea of this photometer, I inclose two sketches ofthe exact size of the instrument. Fig. 239 is a side view of the glass prism before beingmounted; Fig. 240, the front view of same when framed.—J. Fleury Hermagis. CHAPTER XII. CONCERNING CHEMICALS. 109. The next halt in our picture making pilgrimage must be made at thechemical hostelry. Rough treatment is sometimes visited upon botii novice and veteran in thisquarter. The glacier of the Rhone does not twist and turn, and break up and cliangewith more eccentric independence than does the vast out-pour and down-pourof chemical elements, equivalents, and combinations. And yet, where is there anything more grandly beautiful than the Rhoneglacier—where anything so superb as the actions an
Size: 2180px × 1146px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookidwilsonsquart, bookyear1887
