240 



RECREA TION. 



with its own textural firmness, makes the 

 position and curvature of the cornea practi- 

 cally constant. 



The adjustment to focus, or " accommo- 

 dation," is accomplished by movements of 

 the crystalline lens, which we find placed 

 but a short distance behind the cornea. It 

 is covered by an iris diaphragm (sometimes 

 exquisitely tinted) that in the center is per- 

 forated by a round hole, the pupil, the edges 

 of which bear upon the front surface of the 

 lens. Through this aperture we may " see," 

 through the transparent lens, the black 

 chamber within, or we may lighten up this 

 darkness and see into the interior of the eye- 

 ball in a practically useful sense. 



The crystalline is circular and bi-convex. 

 It is attached at its periphery to the inside of 

 the eye-chamber by means of an annular 

 band of folded membrane, like an old-fash- 

 ioned plaited ruff, called the zonule of Zinn, 

 or ciliary body. The tension of this ring is 

 regulated by the fibres known collectively 

 as the ciliary muscle. When this contracts, 

 the diameter of the lens is diminished, and 

 its surfaces — but chiefly that in front — be- 

 come more convex than when the eye is at 

 rest. Thus its refractive power is increased, 

 and the image of even quite near objects 

 brought to a focus accurately on the poste- 

 rior sensitive surface of the eye. — The Opti- 

 cian. 



HOW TO WORK PLATINUM BATH. 



In November Recreation I saw a 

 formula for platinum bath which it is said 

 can be used on any kind of paper for get- 

 ting the platinum finish; but I have tried 

 4 different papers and cannot get any good 

 result on either. Please let me know what 

 the trouble is. Where it says fix in hypo, 

 i to 30, it means 1 part hypo to 30 of water, 

 does it not? 



F. Clarkson, Worcester, Mass. 



I do not understand, from your letter, in 

 what way you fail. The formula published 

 is same as used and published by the Photo- 

 materials Co., and I have no doubt is iden- 

 tical with the preparation put on the market 

 by the Aristo. and Self-toning paper man- 

 ufacturers. If used properly, the results 

 should be good; but it is necessary, as in 

 all things photographic, to use pure chem- 

 icals and right weights and measures. 

 Many amateurs think a grain more or less 

 will make no difference, but it does. If 

 your prints are muddy, the chloride of cop- 

 per is too strong. The solution must not be 

 used over again, as the platinum salt is taken 

 up by the toning process, thereby' leaving 

 an excess of the copper salt. I have used the 

 formula with good results on Solio, max- 

 ima, albuma and Kloro papers, and have no 

 doubt it will work on all kinds. Hypo so- 

 lution 1 to 30 naturally means 1 part hypo 

 to 30 parts water. 



NOTES. 



I have now taken Recreation 2 or 3 

 years and enjoy it more every year. There 

 is one department, however, to which I 

 should like to see more attention paid, and 

 that is amateur photography. I am deeply 

 interested in this science, and you will prob- 

 ably hear from me in the photographic con- 

 test now on. 



Success to the L. A. S. It does me good 

 to see you roast the game hogs. 



J. W. Steward, Battle Creek, Mich. 



If you and a lot of other amateurs who 

 think as you do would send me frequent 

 notes, items, comments, queries and sug- 

 gestions I could soon enlarge the photo de- 

 partment. Try it and see. — Editor. 



Have you ever been annoyed by looking 

 up a good negative, taken some time ago, 

 and finding several yellow stains on it? If 

 so, the offending marks can easily be re- 

 moved by washing the negative and then 

 putting it in water containing a small quan- 

 tity of bromine. Let it dry (in sunlight if 

 possible), wash again, and dry with alcohol. 



By a saturated solution is meant a solution 

 containing as much of the material as the 

 water will dissolve. To be sure that a solu- 

 tion is saturated see that there are undis- 

 solved crystals or a part of the material lying 

 in the bottom of the bottle. 



When developing or handling plates work 

 in the dark of your own shadow and hold 

 the plate for examination, so that the ruby 

 light may pass to one side of you or over 

 your shoulder, and from quite a distance. 



Will some one kindly give me, through 

 Recreation, a formula for a slow emul- 

 sion for bromide paper, that can be worked 

 by gas light. 



Alfred M. Bailey, Lynn, Mass. 



A photographer requires as much patience 

 as the man who waits for fish to bite, when 

 mosquitoes and flies are biting lively at his 

 end of the rod. 



I have prints of California scenery, Gold- 

 en Jubilee, etc., z l / 2 x 3 l / 2 , which I wish to 

 exchange with amateurs. 



F. Hope, Midland, Mich. 



Would like to exchange 4x5 prints with 

 anybody. 



George H. Bayldone, 63 Florence Ave- 

 nue, Revere, Mass. 



ALWAYS MENTION RECREA- 

 TION WHEN ANSWERING ADS. 



