Giant Land Tortoises 201 



been filled wholly with gunpowder, and their number was pro- 

 portional to the rapidity of explosion of the bursting charge. 

 Again, not only is a shell broken into many more pieces by 

 using a very small charge of guncotton, but these also are 

 scattered with much violence, and thus are as effective 

 against troops as the comparatively complicated shrapnel 

 shell. By way of illustrating the detonating power of this 

 water-shell, a wrought-iron gun, having a bore seven inches 

 in diameter, after it had been tilted up and filled with water, 

 had lowered into it a charge of two pounds of guncotton. 

 When this was exploded the gun was split up to the 

 muzzle in three places, and the external coils of wrought 

 iron were torn open. 



Sir W. Grove spoke of his own experiments in obtaining 

 gases by passing sparks through water. When that was 

 wholly deprived of air and perfectly inelastic, the containing 

 globe or tube invariably burst, but the pieces remained on 

 the table instead of being blown away. 



1877. Jan. 25th, 267th meeting. Dr. Giinther gave a 

 summary of the memoir on Gigantic Land Tortoises, 1 which 

 he was to read that evening to the Royal Society, including 

 some earlier memoirs. The isolation of these tortoises was 

 remarkable, for they occurred only in the Galapagos Islands 

 and in Mauritius (where they had become extinct) with the 

 adjacent islands. No intermediate traces of them had 

 been found except some fragmentary bones in Malta. In 

 European Museums specimens of these tortoises were rare, 

 owing either to the fragility of their shells, which made 

 them liable to injury on shipboard, or to the majority of 

 naturalists having referred them all to a single very variable 

 species. But the materials which he had gathered showed 

 them to belong to three distinct groups : one, in the Gala- 

 pagos ; another, in the Mascarenes ; and the third, in Aldabra 

 Island ; each group being represented by several races, the 

 majority of which had become extinct during the last century. 

 The date of their disappearance in Mauritius could be fixed 



1 See Giinther, Gigantic Land Tortoises Living and Extinct in the Collection 

 of the British Museum, 1877. 



