48 



NATURE S TEACHINGS. 



wine, spirits, tobacco, tea, an " etna " for heating the water, 

 and matches. Of course these were on a smaller scale in the 

 boat ; but several thick rugs were also stowed away, in case of 

 being separated from the yacht at night. It so happened that 

 they were never needed ; but the sense of security which they 

 imparted was worth ten times the expense and trouble, which 

 included a careful inspection of all the stores before each 

 voyage. 



In Nature there is just such a raft as is needed, capable of 

 carrying a heavy freight, and which cannot be upset. And 

 it is rather remarkable that it has been unconsciously imitated 

 in various parts of the world. 



JAXTHINA AND AIR-RAFT. 



CASK-PONTOON. 

 POTTERY-RAFT OF THE NILE. 



This is the singular apparatus attached to the Yiolet Snail 

 (Janthina communis), which is common enough in the Atlantic, 

 and derives its name of Violet-shell from its beautiful colour. 

 The chief interest, however, centres in the apparatus which is 

 popularly called the " raft," and which sustains the shell and 

 eggs. It is made of a great number of air-vessels, affixed 

 closely to each other, and by the curious property of bearing its 

 cargo slung beneath it instead of being laid upon it. 



Beneath the raft are the eggs, or rather, the capsules which 

 contain the eggs, and at one end is the beautiful violet shell 

 itself. The floating power of the raft is really astonishing, 

 and even in severe tempests, when it is broken away from the 

 animal, the raft continues to float on the surface of the waves, 

 bearing its cargo with it. 



On the opposite side of the illustration are two examples of 

 rafts constructed so exactly on the same principle as that of the 

 Violet Snail, that they both might have been borrowed from it. 



The upper is the kind of raft which has often been con- 

 structed by sailors when trying to escape from a sinking 

 ship, or by soldiers when wishing to convey troops across a 



