36 



edge of the opening to the deepest point of the nest trough ; and those 

 of the fourth the thickness of the bottom. 



The following are the measurements in milhmetres of the diameters 



20 



A. 



so 



32 



ISO 



eo 



202 



so 



2T 



iSO 



60 



292 



B. 



eo 



U6 



230 



70 



we 



eo 



eo 



300 



70 



490 



D. 



eo 



8S 



27S 



TO 



¥90 



mm. 



Total Heights 

 oftheNesting' 

 boxes in iniUi- 

 inetres. 



of the inside of the nesting-cavities at the various points as indicated 

 in the above diagram ; — 



Nesting-Boxes — 



Size A. Al. 



At A. 60-65 60-65 



„ B. 70-80 70-80 



C. 



D. 



B. 



80-85 

 85-95 



.. C. 85-95 85-95 115-125 160-180 160-180 

 These boxes are made of alder, birch, pine, and other woods which 

 do not Sf)ht easily.* 



* Many boxes were made of bircliwood. Baron von Berlepsch has forbidden 

 the use of this wood in future as it is not very durable. 



