CLIFF-DWELLERS 19 



unlike a human apartment house. Perfect har- 

 mony and peace seem to dwell wherever these 

 birds live. If occasionally a couple have a little 

 "family quarrel," they immediately cease when a 

 group of other martins have assembled. Each 

 family has its own apartment, and lives somewhat 

 independently of its neighbours, yet the whole city 

 is really one great family. 



In the olden times, the people believed that the 

 work of these little cave-dwellers was miraculous. 

 Pliny dignified the sand martin by the following 

 tale: "At the mouth of the Nile, near Heraclea, 

 in Egypt, the swallows build nest upon nest, until 

 they form a wall so strong as to present an insur- 

 mountable barrier to the inundations of the river; 

 this dam is nearly a stadium in length, and could 

 scarcely be constructed by human hands. Near 

 the town of Koptos there is an island sacred to 

 Isis, which these swallows have fortified in a simi- 

 lar manner to preserve themselves from the flood. 

 In the early spring they strengthen the facade with 

 straw and chaff, continuing their labours night and 

 day for three consecutive days with such assiduity 

 that many expire from exhaustion. This work has 

 to be renewed every year." 



There are a number of other cave-dwellers along 

 the banks of the Nile. These are marsh-birds and 



