[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.

Life is short and progress is slow

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.

In the case of composite colour, an infinity of systems must be obtained for maxima infinitely slight and with an infinity of interval values separating them - that is to say, the whole thickness of the sensitive layer is occupied in continuous manner by these maxima.

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

I got quite good results from protein plates.

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