750 Dr. Bottomley and Mr. King : Experiments with 



period of the clock could be greatly augmented. In one case 

 which we have noted, the striking on the side -plates was 

 delayed, by alternately placing the hand to the right and to 

 the left o£ the gold leaves, to such an extent as to make an 

 interval of 6J- minutes, the normal period of charge and 

 discharge, at the time, being 3 minutes 4. seconds. 



Radium tube. 



Left 



Right! 



Experiment 4. — To try the effect of cold, a test-tube was 

 filled with water, and with the help of a vessel filled with 

 liquid air, the water was first frozen, and was then cooled 

 down nearly to the temperature of the liquid air. We had 

 thus a bar of solid matter, having a great capacity for cold, and 

 chilled to a very low temperature ; and this was brought near 

 to the clock, just as had been done with the flame and with 

 the bar of heated copper. When the bar of chilled ice was 

 brought near to the leaves they were markedly attracted ; 

 and, in fact, the action of the chilled body appeared to be 

 exactly the inverse of what we had observed in the case of 

 the heated bar of metal. 



Experiment 5. — When the clock was covered entirely with a 

 cage made of fine brass gauze, and the gauze cage connected to 

 a neighbouring gas-pipe, the peculiar attraction and repulsion 

 of the gold leaves was still observed, with but little diminution 

 in intensity, when hot and cold bodies were presented, as 

 described above. 



The leaves, however, under these circumstances, were 

 unaffected when electrified rods of glass and sealing-wax were 



