Professor Duns on the Nesting of the Eider Duck. 155 



points that the mice intended to cut their way when, no 

 doubt much to their surprise, an escape of gas suddenly 

 checked their chiselling operations. Sometimes, however, 

 they gnaw the pipe midway between two joists when it nearly 

 fills the space between the boards of the floor and the upper 

 surface of the " deafeninc?." Instances also occur of their 

 biting holes in vertical tubing when they want to get up or 

 down. It will be easily understood that the holes they 

 make are never large, as they must beat a retreat whenever 

 the gas leaks. Mice, and apparently rats also, usually blacken 

 a gas-pipe to the extent of a few inches before they begin to 

 gnaw it. This black stain, when soaked in distilled water, 

 filtered, and tested with nitrate of silver, shows abundance 

 of chlorides, indicating dried urine. Probably the simplest 

 way to prevent these animals from experimenting with their 

 teeth on gas-pipes would be to see that they have " head- 

 room " to race about under the floor, and to make notches in 

 the joists for them as well as for the pipes, because, like wise 

 engineers, they never tunnel without first making an accurate 

 survey of the ground. Tin pipes, are, however, pretty nearly 

 safe from their attacks ; iron ones, we know, completely 

 baflle them. 



VI. The Nesting of the Eider Duck. By Professor Duns. 



(Read 21st December 1881.) 



Abstract. 



Three nests of the Eider Duck (Somateria mollissimci) 

 were exhibited, two from the Isle of May, in the Firth of Forth, 

 and one from Norway. Of the Forth specimens, one con- 

 tained five eggs, and the other one Qgg. The Xorway 

 specimen contained five eggs. Dr Duns referred verbally to 

 the Avide diflerences of opinion among naturalists as to the 

 number of eggs deposited, and the weight of the down in a 

 nest. Pontippidan's description of the Edderfugl, 1751, was 

 noticed. Von Troil, 1780, and Henderson's "Iceland," 1818, 

 were also referred to. As bearing on the Firth of Forth 

 specimens, an extract was read from De Saussare's " Voyage 



