102 



THE NEW KNOWLEDGE. 



versed the polarity, thinking that, if the rays bent at all, 

 they would bend in the opposite direction. Fig. 31 is the 

 .-_, answer clear as sunlight. The plate shows 

 two broad bands, proving that the rays must 

 have been curved down to meet it; that 

 there are two bands instead of one proves 

 that reversing the polarity causes the rays to 

 bend in the opposite direction. Becquerel 

 rays are deviable by a magnet. But are they 

 all equally deviable? Are they homogene- 

 ous? Upon another plate of the same kind 

 he placed strips of platinum, aluminum and 

 paper, and at the end of the plate, as before, 

 the little lead trough containing the radium 

 compound. If they were all equally devi- 

 able, they would form a line when they bent 

 to meet the plate ; if not, they would form a 

 band. After energizing the magnet and de- 

 veloping the plate, he obtained the result 

 shown in Fig. 32. The rays are not equally 

 deviable ; 



. 



they form 

 a broad 

 band, a 

 veritable 



Fig. 31. 

 The magnetic 

 deviation of 

 Becquerel 

 Rays. 



spectrum, of an infinity 

 of rays unequally devi- 

 able. The same plate 

 shows as well that the 

 rays penetrate the 

 screens in this order: 

 the platinum least, the 



Fig. 32. Radiograph showing how the 

 power of the rays to penetrate matter de- 

 pends on the density. The strips A , B 

 and C are platinum, aluminum and paper 

 respectively. It is easy to see that the 

 platinum is penetrated least. 



aluminum next, and the paper most of all. Are they all 



