[On the Gaussian curve, remarked to Poincaré:] Experimentalists think that it is a mathematical theorem while the mathematicians believe it to be an experimental fact.

When the shot is afterwards subjected to white light, colour appears because of selective reflection.

Life is short and progress is slow

The problem of direct colour photography has been facing us since the turn of the last century.

The series of photographic operations, developing, washing, final drying, takes about quarter of an hour.

I got quite good results from protein plates.

Most of these pictures, taken while travelling, were developed on the mantelpiece of a hotel room, which proves that the method is easy enough to carry out.