214 Proceedings of the Royal Physical Society. 



The inquiry is carried on as a piece of research work from the Natural 

 History Department of the University of Aberdeen, under the supervision 

 of Professor J. Arthur Thomson. The working expenses are covered by 

 a grant allowed us by the Carnegie Trustees. 



In the work of ringing birds, we have the co-operation of a large number 

 of ladies and gentlemen, who have kindly volunteered their assistance. 

 Most of these co-operators live in Scotland, especially in Aberdeenshire, but 

 there are a few in England and Wales and in Ireland. Most of them rely 

 chiefly on young birds, found when still unable to fly, varied by occasional 

 chance captures of adult birds. A few, however, engage systematically in 

 bird-catching during the winter-months : the chief means employed are 

 simple clap-nets, automatic cage-traps, or other harmless appliances ; but a 

 number of birds, mostly gulls on the shore, have been caught at night by 

 means of acetylene cycle-lamps, which completely dazzle and bewilder them. 

 After a good deal of experimenting with different sizes and patterns of 

 rings we have fixed upon the following eight sizes, the measurement in each 

 case is that of approximate internal diameter of the ring (when closed in 

 circular shape) : — 



i inch : for Finches, Swallows, Tits, Eobin, Lark, Sandpipers, Lesser 



Tern, etc. 

 - a 'V „ for Common and Arctic Terns, etc. 

 y\ „ for Lapwing, Snipe, Starling, Blackbird, Thrushes, etc. 

 I „ for Woodcock, Jackdaw, Black-headed and other small Gulls, 



Kestrel, Teal, Stock-Dove, etc. 

 ,',; „ for Book, Hooded and Carrion Crows, Owls, Wood-Pigeon, 



Guillemot, etc. 

 | „ for Mallard, Herring and Lesser Black-backed Gulls, etc. 

 t} „ for Great Black-backed Gull, Gannet, etc. 

 f „ for Heron, etc. 

 The first four sizes are of the simple claspless pattern, the last four are 

 provided with Kossitten clasps : the last three have the edges turned out all 

 round as flanges. The address on all the rings is " Aberdeen University," 

 except that it is contracted to " Aberdeen Univ." on the two smallest sizes. 

 The impossibility of getting a five-figure number on to a very small ring 

 has necessitated the use of letter combinations (e.g. " 299A ") on some of these, 

 and we also use numbers like "0798": otherwise plain numbers are used, 

 although often written in two lines on a medium-sized ring. All our rings 

 are made from aluminium, by Mr Samuel Drake, Halifax. 



Each co-operator is provided with a list of the commoner species for which 

 each size of ring may be used. Early in each year he fills up and sends to 



