On the Theory of the Sphygmograph.

Many debates have already taken place on the reliability of the results obtained by means of sphygmographs. The following remarks may contribute to clarify some still unsettled points.

Remarks on Scientific Applications of Photography.

It is undisputed that all scientific knowledge proceeds from sense perception. And the way in which sense perception is fostered by the graphic arts generally, and in particular by photography (stereoscopy included), likewise needs no further explanation here.