The philosophical interest for the « visibility », - Sichtbarkeit -, at the end of the XIXth century, involved a new interaction between art, science and technique. The drawing combines graphic arts as science of « visible ». Vitruve already establishes that the « science of the architect » – Architecti scientia – takes value and is reinforced by the « science of the drawing » – Graphidis scientia. The research relates to the analysis of the drawing which the architect uses and produces when he works to educate himself, according to his own referee and his own means, out of schools and the workshops, in the bend of the XIXth in the XXth century. Charles-Edouard Jeanneret (1887-1965), Paul Tournon (1881-1964) and Jean-Charles Moreux (1889-1956) travel for their learning. They look at the world and transcribe their astonishment activated in contact with reality. In the same way to form, while their architectural production will be very different, they note in drawing. We interview the intellectual and graphical reduction of note drawing, as a short form of representation. The short form is the conscious work of analysis and of synthetic research. Each feature is thought and thought like materiality. It is a conceptual act of abstraction. How this short form, that we interpret in his theoretical vocation, takes part-such of the acquisition of the architect's trained glance ?
