CONTENTS. 
V 
ILLUSTRATIONS. 
Page 
Figure 1. Theoretical iceberg.•... 51 
2. Results of gravity measures...•. 55 
3. Pendulums. 58 
4. Lens of microscope. 242 
5. Comparing apparatus. 245 
6. Abutting pieces for comparisons. 246 
7. Abutting pieces for comparisons .. 246 
8. Abutting pieces for comparisons. 247 
9. Abutting pieces for comparisons. 247 
10. Same in position. 248 
