62 



Prof. J. 0. Bose on a Complete Apparatus for 



A rrangement of the Apparatus. 



The radiating apparatus and the receiver are mounted on 

 stands sliding in an optical bench. Experiments are carried 

 out with divergent or parallel beams of electric radiation. To 

 obtain a parallel beam, a cylindrical lens * of sulphur or 

 ebonite is mounted in a square tube. This lens-tube fits on 

 the radiator-tube, and is stopped by a guide when the oscil- 

 latory spark is at the principal focal line of the lens. The 

 radiator-tube is further provided with a series of diaphragms 

 by which the amount of radiation may be varied. 



For experiments requiring angular measurement, a spectro- 

 meter-circle is mounted on one of the sliding stands. The 

 spectrometer carries a circular platform, on which the various 

 reflectors, refractors, &c. are placed. The platform carries an 



Fig. 4. — Arrangement of the Apparatus. 

 R M 



F 



R, the Radiator. T, the Tapping Key. S, the Spectrometer-Circle. 

 M, the Plane Mirror. C, the Cylindrical Mirror, p, Totally 

 Reflecting Prism. P, the Semi-Cylinders. K, the Crystal-Holder. 

 F, the Collecting Funnel attached to the Spiral Spring Receiver. 

 t, the Tangent Screw, by which the Receiver is rotated. V, Voltaic 

 Cell, r, the Circular Rheostat. G, the Galvanometer. 



index, and can rotate independently of the circle on which it 

 is mounted. The receiver is carried on a radial arm (provided 

 with an index) and points to the centre of the circle. An 

 observing telescope may also be used with an objective made 

 of ebonite with a linear receiver at the focal plane. But an 

 ordinary receiver provided with a funnel is all that is necessary 

 for ordinary experiments. 



* See Lodge and Howard, Phil. Mag. July 1889. 



