Miscellanies. 165 



a wild state, he observes, some birds of the same species have a 

 much greater variety of notes than others, and are much better song- 

 sters. 



Another correspondent maintains that the Well known habits of the 

 cuckoo, prove that the songs of birds are innate, and not acquired. 

 He saw one of these birds, (which had been found half fledged in 

 a field,) in a house, in a narrow street, where it had probably never 

 seen or heard one of its own species, but which at the sight of its 

 protectress, or when hungry, would cry cuckoo ! cuckoo ! in the nat- 

 ural tone. 



Perhaps some of our readers, from their own observations or ex- 

 periments, may be able to throw light on this question, which, in a 

 physiological point of view, possesses some interest. 



MECHANICAL PHILOSOPHY. 



1. To prevent the cracking of lamp glasses, by the sudden ex- 

 pansion produced by the heat ; an effectual remedy is found in run- 

 ning a point of a diamond along the base of the tube. By this solu- 

 tion of continuity, it is relieved from, the violence produced by the 

 sudden effects of the heat. A glazier can best perform the opera- 

 tion with the diamond. — Jour, des Connois. Usuelles, Jan. 1830. 



2. On giving a fine edge to razors, lancets, and other cutting in- 

 struments. — In a paper on this subject by Thomas And. Knight, Esq. 

 F. R. S. the following method is recommended as preferable to any 

 other which the author has tried. 



A cylindrical bar of cast steel is provided, three inches long with- 

 out its handle, and about one third of an inch in diameter. It is ren- 

 dered as smooth as it can be made with sand, or, more properly, 

 glass paper, applied longitudinally ; and it is then made perfectly hard. 

 Before it is used it must be well cleaned, not brightly polished, and 

 its surface must be smeared over with a mixture of oil and the char- 

 coal of wheat straw, which necessarily contains much siliceous earth 

 in a very finely reduced state. Charcoal of the leaves of some of the 

 marsh grasses the author thinks, may perhaps answer as well or better. 



In setting a razor, its edge (which must not have been rounded by 

 a strap) is brought into contact with the surface of the bar, at a very 

 acute angle, proportionate to the strength intended to be given to the 

 edge, and the razor is to be moved in a succession of small circles 

 from heel to point, and back again without any more pressure than 



