Franz Schmidt & Haensch. Berlin S. 



77 



e) Reflecting Prisms of various sizes. 



f) Heliostats of various types. (Fig. 14, according to Spencer.) 



Fig. 14. 



g) Spectrum tubes and tables etc. 



B. Photometric Appliances. 



The increased requirements of stronger and better artificial illumi- 

 nation have created a demand for accurate appliances for measuring the 

 power and quality of illuminants. 



The following appliances constructed by this firm have met with 

 particular favour: 



I. Leonhard Weber's Photometer. 



The instrument is adapted not only for determining the intensity 

 of flames or similar illuminants but also that of diffuse light. (Fig. 15.) 



The apparatus with its accessories is neatly fitted in an elegant 

 case with handle; it is conveniently portable and therefore specially 

 available for measurements of any kind, in cases where other photometers 



