25 



branches of trees in the woods, it will often disappear while the 

 novice is trying to follow it with such a glass. A common 

 opera glass of good quality, with a larger field of vision and 

 magnifying about three times, will do very well for ordinary 

 use. Each glass should be tested before purchasing, and the 

 purchaser should, if possible, select a glass with the eyepieces so 

 adjusted that in using it he can see but one field. If he sees 

 "double" the glass is "out of line." For waterfowl or sea birds 

 a marine glass is useful. 



To learn the proper use of the opera glass, select some bird 

 in the open that is sitting still, if possible. Have your back to 

 the sun, so that it will shine directly on the bird. Focus the 

 glass on the tree, and then find the bird by noting the position 

 of the branch and sighting the glass as you w^ould a gun. 



Points to be Noted. 



Note the size of the bird. It will be difficult at first to judge- 

 this size in inches, but you may compare it with certain com- 



CHlPKHCSPARftCW. sens SPAR ROW. 3t.UEBI1?U. CATBIRD ■ KOBIN. 



Scale of sizes. 



OOVt. 





mon and w^ell-known birds. You may have a scale of sizes, 

 beginning with the yellow warbler or chipping sparrow, and 

 reading like this: chipping sparrow, song sparrow, bluebird, 

 catbird, robin, dove, crow. Observe these birds well, and note 

 the size of each. Turn to your book and get it in inches. 

 Write it down; commit it to memory; have it always in mind. 

 By making good use of such a scale, you may become expert in 

 judging size by comparison. 



