Collection and Mounting of Objects. 25 



sets about it as only one I pick out thin glass 

 covers of corresponding sizes, each slightly larger 

 than the circle which it is to fit ; these I make per- 

 fectly bright and clean by rubbing with a soft hand- 

 kerchief. Then I lay the little papers white side up, 

 and putting some gum thinly round the aperture, lay 

 the cover on it, 6, and leave it to dry, endeavouring 

 to put it out of the way of dust. When it is dry 

 (and we know how quickly a thin coat of gum dries, 

 as in an adhesive envelope if we want for any reason 

 to open one which we have lately closed), I get the 

 slide ready to have the object placed upon it, by first 

 making it as bright as possible, and then placing an 

 ink spot on the under surface of it to mark its centre, 

 and of course to be afterwards rubbed off. If I wish 

 the preparation to look very smart and precise, I 

 rapidly rule ink lines from the opposite corners, know- 

 ing their crossing-point will be the exact middle of the 

 slide, c. Just over that, on the upper surface, I lay 

 the insect's wing ; then painting a little gum near the 

 edges of the paper, 6, I lay it down over the wing, 

 looking to see that the circle frames the object cen- 

 trally, then I press it down, and lastly trim the 

 projecting edges of green paper with a pair of scissors. 

 If I feel it at all possible that I could forget the name 

 of the specimen, I write it in a temporary way in ink 

 somewhere on the glass ; but ultimately, (namely, 

 when I have a number of slides ready,) I place neatly 

 upon the slide, d, two little cut-out green labels, 

 (" to make the balance true,'') the right-hand one 

 with the name of the object, the left with the mag- 



