Note 1 — Chapter I
Rudolf Pintner translation
To carry out such experiments more exactly and more uniformly it is best to make use of the simple apparatus called the tachistoscope. A falling screen exposes the object to sight for a very short time, which can be accurately measured. Still, if this apparatus cannot be procured, the procedure described above suffices. Special practice should be devoted to covering and uncovering the diagram, so that this may be done as rapidly as possible.