THE AMATEUR SCIENTIST.

The article discusses the method and mechanism for photography of air currents. Details are given on how to build an accurate Focault pendulum. Comments and instructions are presented from Robert Walan, a senior at the Carnegie Institute of Technology who built an apparatus for photographing air-density that records convection currents and flow patterns and represents zones of different pressure. Walan explains that his system is essentially a means for making what are called Schlieren photographs, only with the difference that what it recorded are refraction effects in colors, rather than in monochrome.