1h 
the yellow-orange rayfilter which was fitted to the lens in order to 
equalize the intensity of the light and compensate for the predominat- 
ing actinic effect of the violet and blue rays. The plate was developed 
in a metroquinone solution, cleared in potassium permanganate and 
reversed by re-development in the monomethyl-para-amidophenol sul- 
phate and hydroquinone. 
Six years ago the writer exhibited before the San Diego Society 
of Natural History several direct-color photographs of still life such 
as fruit, flowers, ete., but at that time the process required an extremely 
long exposure through thick color filters, which made it impractical for 
landseape photography. One of the photographs shown at that time 
was a study of a few clusters of Tokay and Muscat grapes ; this picture 
required an exposure of 40 minutes through the orange-red filter, and 
proportionate exposures when using the green and violet filters. 
In the Lumiere process the proceedure is rendered very simple 
and the speed is only about two hundred per cent. greater than in 
ordinary photography. Through the courtesy of the brothers Lumiere 
the following outline of the process is given herewith: ‘‘Autochrom 
plates differ from ordinary plates as follows: Interposed between the 
Sensitive coating and the glass is a thin layer of transparent miseropi- 
cal starch grains, dyed orange-red, green and violet, spread without 
overlapping, and mixed in such proportion that the layer appears col- 
orless when examined by transmitted light, and absorbs but a small 
percentage of the light received. The sensitive coating is extremely 
thin, and made of a special fine-grained panchromatic emulsion. When 
such a plate is exposed in the eamera, the glass side towards the lens, 
the light, before reaching the sensitive coating, passes through the 
colored stareh grains, which act individually as minute screens, each 
one absorbing all colors but its own. A microscopical selection takes 
Place, and after development there is found under each grain a cor- 
responding black spot, reduced silver of a density proportionate to 
the amount of eolor reeeived and transmitted by this particular grain. 
Were the plates fixed at this stage, the picture when examined by 
t ‘ansmitted light, would show only the colors complementary to those 
In the original, sinee the true colors are masked by the black spots 
beneath the erains. But when the reduced silver is dissolved in the 
Permanganate solution, the image is reversed: the opaque image under 
each grain becomes translucent and transmits colored light precisely 
of the same hue as the light transmitted by the grain when the plate 
was exposed in the camera: in other words the color is reconstructed 
Just as it was decomposed during exposure.”’ 
Mt aes the bibhograpily of sphaerella nivalis ineludes the writings 
he ancient Greek philosophers, Swiss geologists, arctic explorers, 
