COLOURED PHOTOGRAPHY DISCOVERED AT LAST.

New Zealand Herald, Volume XXXV, Issue 10908, 12 November 1898, Page 5 (Supplement)

COLOURED PHOTOGRAPHY DISCOVERED AT LAST.

EVERY HUE OF FLOWER, TREE, GRASS, OR ANY OTHER OBJECT ACCURATELY REPRODUCED.

THE DISCOVERER DIED JUST AS HE

ATTAINED SUCCESS. Chicago. 111., September Colour photography has been made a final success by a Chicago man. The process of using an ordinary camera ant', in one-fifth of a second accurately photographing all of the brilliant hues of a flower garden, all the contrasts in green of a landscape, all the wonders of x summer sky, the jewel upon your linger, the ribbon at your throat, the stripes in your clothes, the decorations of your hat, the bouquet 011 your lapel, is now a reality. Not a canvas of the old masters but what may be reproduced, with even- tint of the original. This discovery and its practical application is the work of the late James W. .McDonough. of Chicago. He has been dead a year, but what he discovered Las been in the "hands of friends and business associates ever since. What he discovered is due primarily to the dirty and nasty condition of the Chicago River. Crossing the river on (lie Madison-street Bridge one day. in 1870, Mr. McDonough noticed on the' surface of the murky water the colours of the spectrum caused by escaping oil from some nearby warehouse. The tlltmght came to him that the river would present a beautiful spectacle if covered with those colours.

His second thought was as to why that river's surface could not be photographed. From this thought gradually developed and grew the process of colour photography— first ever given to the world—that will always be known as McDonough's. Mr. McDonough was in the early years of his life wealthy and given to scientific pursuits. His work in connection with the telephone was primarily along the line to the discovery of the receiver, and he fought his rights in the courts until he and all others were defeated.

Worn in health and weakened in fortune Mr. McDonough turned from the telephone to his old dreams of colour photography, and pursued them until satisfied that the work could be done. He died just as success was at hand.

Hie process that he created is a colour photography which is purely mechanical. The ordinary camera is used, and the negatives are produced and developed by the usual processes, but before exposing the negative in the camera a transparent screen ruled with the three primary colours is interposed between the negative and object to be photographed. After developing the negative a positive plate is produced from it. which, viewed by itself, does not differ from the ordinary black and white plate, but when it is laid upon a viewing screen, ruled with the primary colours, a duplicate of the taking screen used in the camera, the colours in the object photographed appear. The principle of colour photography is a mixture of coloured lights on the retina. A transparent medium is ruled in fine coloured lines, 300 to 600 to the inch. These lines are red, blue, and green, commonly speaking. They are the fundamentals of the spectrum —the yellow of school days now being rejected—and their mixture produces white light. In other words, the colour of each is such as to absorb the remaining two and transmit only its own light. To make a picture it is necessary to placo one of these ruled screens in immediate contact with the sensitive surface of the dry plate and expose the same as in ordinary photography. The sensitive plates must bo what is known as isochnunatic plates— is, senstitive to all the colours of the spectrum.

After a negative is made a positive is also made by contact printing, as in the usual manner. This positive is then placed over the ruled screen and the dark lines on the positive are made to register with the coloured lines on the screen. When this is done the picture is seen in its natural colours. Paper photographs are made by printing in the usual manner on the sensitive paper ruled with the three coloured lines, as on the screen. Half-tone pictures in colours are also made by print-ing with black ink—from a half-tone plate made from the original upon paper having the three coloured lines ruled on its surface, the same as a screen.

McDonough the day before his death photographed himself in' one of the flower gardens of Jackson Park. He never lned to see the picture completed, but it stands to-day in an office in Dearborn-street with every hue of the blossoms surrounding him faithfully reproduced— work of the sun and the sun only.