HO USE-MA R TINS. 



by choice in or over a porch or doorway, whether of 

 house or stable, or over a window somewhere where 

 man is about It is curious that in this country, so sub- 

 ject to cold and cold winds, so many houses arc built to 

 face north or east, and this fact often compels the house- 

 martin to build that side, the back of a house being fre- 

 quently obstructed. In the case of house No. I there 

 was a clear take-off on the north side, also with the 

 stable. Houses are generally built to face the road, 

 quite irrespective of the aspect, which custom is the 

 origin of many cheerless dwellings. I think that house- 

 martin fledglings and eggs are capable of enduring the 

 utmost heat of our English summer, and the nests found 

 deserted were abandoned for some other reason. More 

 likely that the deficiency of insect food caused by the in- 

 clement weather weakened the parent. Sometimes these 

 harmless and useful birds arc cruelly shot. I have never 

 seen a nest injured by heats ; on the contrary, I should 

 imagine that heat would cause the mortar to cohere 

 more firmly, and that damp would be much more likely 

 to make it unsafe. At house No. 2 the heat in the angle 

 of the two walls was scarcely bearable on a July day. 

 If a nest were taken down and put in an oven I should 

 doubt if it would crack. In nature, however, everything 

 depends on locality. The roads in that locality were 

 mended with flint, and the mortar from puddles appeared 

 to make good cement. Possibly in some districts there 

 may be no lime or silicon, and the mortar the birds use 

 may be less adherent The more one studies nature the 

 more one becomes convinced that it is an error to sup- 

 pose things proceed by a regular rule always applicable 

 everywhere. All creatures change their habits with cir- 

 cumstances ; consequently no observation can be accepted 

 as final. 



