MARTIN. 257 



before additional weight is superadded. When the exter- 

 nal circular wall is finished, the cavity within is lined with 

 a few bents of hay and some soft feathers, and the nest 

 thus completed is frequently occupied by both birds at the 

 same time, who thus appear to enjoy the habitation their 

 united industry has achieved. In some instances these 

 birds build under projections against the surface of high 

 cliffs, as those referred to by Mr. Couch on the Cornish 

 coast, and others mentioned by Mr. Selby as occurring 

 about St. Abb's Head, on the coast of Berwickshire. 



The Martin produces three, and sometimes even four, 

 broods in the season. Dr. Jenner, writing from home, 

 says, " A pair of Martins hatched four broods of young 

 ones in the house of a tradesman in this place in the year 



1786. The latter brood was hatched in the early part of 

 October. About the middle of the month the old birds 

 went off, and left their young ones, about half fledged, 

 to perish. The pair returned to the nest the 17th of May, 



1787, and threw the skeletons out." 



The eggs are four or five in number ; they are smooth 

 and white, measuring nine lines and a half in length, and 

 six lines in breadth. Incubation lasts thirteen days. The 

 young are at first fed by the old birds going into the 

 nest to them ; after a time, the young thrust their heads 

 out at -the opening on the arrival of either parent bird, 

 who feeds them while hanging on by their sharp crooked 

 claws to the rough outside of the nest. The old female 

 begins to lay again as soon as each young brood is able to 

 leave the nest. As the season advances a smaller number 

 of eggs are produced ; but White says they are never 

 without unfledged young ones as late as Michaelmas. 



The subject of the Martins deserting their young has 

 been adverted to. This singular fact in their economy has 

 been particularly attended to by Mr. John Blackwall, and 



VOL. II. S 



