Proceedings. i i 



College Museum, but smaller. The German specimens 

 were found in collieries near Osnabruck. Two only were 

 preserved, one of which is in the Osnabruck Museum, while 

 the other has been placed in the museum of the Berg- 

 Akademie. The longest root of the German specimens 

 measures 13ft., while the longest root of the Owens College 

 specimen measures nearly 21ft. The diameter of the stem of 

 the latter is 4ft. against 2ft. that of the former. But while the 

 Owens College specimen of an older tree has no cortical 

 markings, the specimen in Berlin has markings showing 

 where the vascular bundles passed through the bark to the 

 leaves. The German specimens afford further evidence that 

 the plants were Lepidodendroid. The dichotomous structure 

 of the roots is clearly shown. 



Mr. Charles H. Lees, M.Sc, read a paper "On a 

 method of determining the Thermal Conductivity of bad 

 conductors, with the results of experiments on Flint and 

 Crown Glass." Mr. Lees referred to experiments by Pro- 

 fessor Kundt, of Strassburg, apparently showing that in 

 certain metals the refractive index is, roughly speaking, 

 inversely proportional to the electric and thermal conduc- 

 tivities. Mr. Lees instituted the series of experiments 

 described in order to see whether the same holds good as 

 regards other substances. The results obtained for glass ap- 

 peared to support Professor Kundt's result, that the thermal 

 conductivity is proportional to the velocity of light in the 

 substance experimented on. — A discussion ensued, in which 

 Mr. C. N. Adams, Professor SCHUSTER, Mr. William 

 Thomson, and Professor REYNOLDS took part. Professor 

 Schuster, while admitting the value of experiments so 

 carefully carried out as those described by Mr. Lees, 

 expressed doubt as to whether what was taken as the 

 refractive index of Professor Kundt's metallic prisms could 

 be safely regarded as corresponding to the refractive index 

 of a glass prism. 



