VIII. 



H 



TO-DAY, a friend who is by no means curiously in- 

 clined regarding science at large brought me an object 

 which he alleged he had purloined from the cage of 

 a canary bird in the house of an acquaintance. 

 Curiosity had for once got the upper hand of him, 

 and, after a hot discussion with the owner of the cage 

 and bird regarding the nature of the object in question, 

 my friend seized the article in question and bore it off 

 in triumph for elucidation on my part. 



The object was a plate of lime to be strictly correct, 

 of carbonate of lime, or, in plain language, chalk. It was 

 of oval shape (fig 12), about four or five inches long, 

 convex on one side and flattened on the other. More 

 closely inspected, it was seen to be made up of layers 

 of limy matter, superimposed one on the other. This 

 object is familiar enough, as I assured my friend, 

 in every bird-dealer's emporium. It is hung in the 

 cages of birds that they may peck at it, and obtain 

 therefrom the limy materials which are essential for 

 their health, especially in reference to the laying of 

 eggs and the due formation of the shell. The bird- 

 owner had assured my friend that the object was a 

 "cuttlefish-bone ; " and so, doubting the science of his 

 acquaintance, he bore off the disputed article to me, 



