Monocle Monocular Vision
For use : Mix Nos. I and 2 in equal parts ; mix Nos. 3 and 4 in equal parts; then mix the two solutions, and suspend the glass in it. To silver copper or any metal it must first of all be cleansed with dilute acid to free from dirt, etc., then well washed, and one of the following applied: - Dissolve 60 grs. of nitrate of silver in 1 oz. of distilled water; add sufficient liq. ammonia to redissolve the precipitate first formed ; add to this solution £ drm. of caustic potash solution andof glycerine ; apply to the metal; add
a few drops of ether ; rub with a tuft of cotton-wool; dry before the fire, and polish ; repeat as often as desired to brighten it. Or
Nitrate of silver ... ... ... ... 65 grs.
Liq. ammonia ... ... ... ... 60 mins.
Hyposulphite of soda ... ... ... 100 grs.
Prepared chalk ... ... ... ... 100 ,,
Distilled water ... ... ... ... 1,000 ..
Mix, and apply with a flannel. Or
Nitrate of silver ... ... ... ... 60 grs.
Cream of tartar ... ... ... ... 120 ,,
Salt.................. 120 ,,
Cyanide of potash ... ... ... ... 60 ,,
Make into paste with water and chalk, and apply with a flannel.
Monocle. Under this term have been introduced uncorrected spectacle lenses, which have been strongly recommended for portraiture and ordinary landscape work where softness of defini-tion is desired. The usual form of lens employed is the peri-scopic of aboutdiameter, and it may be obtained of any
focus from about 6-in. and upwards. These lenses, being un-corrected, necessarily have two foci, a chemical and visual, and it is therefore necessary to make a correction after focussing and before exposing. For ordinary landscape work the necessary correction may be made by means of the formula which is practically equal to TVth of the focus. But this only applies when the lens is working at its equivalent focus.
Monocular Vision. As the term implies, it is seeing with one eye only. It was formerly supposed by many eminent opticians and physicists that one eye only was employed in vision ; but Wheatsone, to whom the great invention of the