266 K. YAMAGAWA 



Uie «iirfiice temperature uiore nearly ap])roached the temperature of 

 the bath. There .seemed to l)e a limit to this effect of stirrinor as 

 indeed there oim-ht to 1h», so that after a certain deofree of asfitation 

 further inrrease caused no appreciable change in maximum and min- 

 imum tenij)LTatures. Al this limit, it may be supposed that the 

 surface temperature was same as that of the bath. The experiments 

 were i)i'rformcd always with tliis limitinii' vi":or of a"'itation. 



The heating bath was made of copper of about oO cubic decim- 

 eters in capacity, and was lieatcd by means of a charcoal fire. The 

 water contained in the bath was maintained always boiling. In order 

 to accomplish this, two tubes from separate boilers were dipped into 

 the Ijath so as to have their muzzles near the sphere, wdien the latter 

 was in position. The steam from these tubes kept the water in a 

 constant state of violent agitation, and this combined with tlie 

 bubbling of the water itself from the botton of the bath produced 

 stirring euDiigli to warrant us in assuming that the temperature of the 

 surface of the sphere to be equal to that of the Ijath. 



The cold l^ath was of about the same capacity as the hot bath, 

 and contained water mixed with a large quantity of pounded ice. 

 Over the bath, a tripod of wooden poles was placed, from which the 

 sphere with its accessories was suspended. A man sitting near kept 

 the whole apparatus constantly shaking to and fro, so that the water 

 in contact with the sphere was constantly changing. 



The stone sphere rested on a horizontal ring, which was suspended 

 by four stout wires from the thick wooden board, which served as a 

 cover for the l)atli. The l)i)ard had a sliding door, which was closed, 

 when the sphere was in the hot batli, and opened when in the cold 

 bath. This was f )uiid necessary, as it was difficult to maintain the 

 water in a l)oiling slate without a co\er ; and then, on the other hand, 

 when the s])here and its belongings wcreremoxed to the cold bath, the 



