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X. OPTICAL AIDS TO BIRD STUDY. 
A. Introduction. Any device that aids vision will be of value in bird 
watching. Opera or “field” glasses, with magnifications up to 4 power, 
are more or less helpful, but prism binoculars are recommended; 6x30, 
7x35, or 8x40 are best for birding. Selection of binoculars should be 
based on these factors (in order of importance) : quality of the optical 
parts; light-gathering power; width of field; and magnification. 
B. Dealers and Manufacturers. These sources are considered reliable: 
1. Bausch & Lomb Optical Co., 574 Lomb Park, Rochester 2, N. Y. 
2. Charles W. Mayher & Sons, 5 South Wabash Ave., Chicago 3, III. 
3. The Mirakel Repair Co., Mount Vernon, New York. 
4. Carl Zeiss, Inc., 485 Fifth Avenue, New York 
C. Publications on Binoculars. For complete information, consult: 
1. “Know Your Binoculars” G, by Robert J. and Elsa Reichert. 12 pp., 
illustrated. Reprinted from “The Audubon Magazine,” 1951. Dis- 
tributed by The Mirakel Repair Co. 10c. 
2. “How to Choose Binoculars” G. Distributed by Bausch & Lomb 
Optical Co. Free. 
Your enjoyment and knowledge of bird study will be enhanced by the 
mutual help and companionship of the members of your local bird club. 
If you wish to join a group, write the Illinois Audubon Society for the 
name of the one in your community. 
If any questions have not been covered by this list, or if you have any 
other problems involving study of birds or establishment of a local nature 
study group, write to the Illinois Audubon Society. We will provide infor- 
mation, if we have it, or notify you where full details may be obtained. 
i - fz 
Increase in Dues Postponed 
The Board of Directors of the Illinois Audubon Society has voted to 
defer the increase in memberships announced in the previous issue of The 
Bulletin. Instead, members have been asked to make contributions to the 
treasury in addition to their dues, particularly those members in the Chi- 
cago area, who are able to attend the “Audubon Screen Tours” free of 
charge. 
It was also hoped that the income of the Society could be increased by 
the sale of literature described in the preceding article. Publications may 
be ordered by mail, or may be purchased at the desk before or after the lec- 
tures at the Museum. Books on nature study make excellent Christmas 
gifts, and the Society has made a point of stocking books for beginners and 
children. As a special Christmas gift, send someone you know a membership 
to the Society. 
The dues for the Society will remain, at least for the present, the same 
as shown on the back cover of The Bulletin. We plan to place all dues on a 
fiscal basis beginning January 1, 1952. If your membership is about to ex- 
pire, please send in your remittance before the end of the calendar year. 
