WORK FOR THE CITY. 89 



snow-crystals vary in shape with heat and cold and 

 density of air, etc- 



The frost pictures on the window, too, are well 

 worthy your attention. Each form is fashioned accord- 

 ing 1 to some fixed law; yet so varied are the beautiful 

 shapes, so intricate the crystalline curves and angles, 

 that it requires much patient study to trace the opera- 

 tion of cause and effect. Many of our members have 

 photographic outfits, and they could render valuable 

 service by securing" pictures of these fairy frost-pencil- 

 lings. 



Indoors, again, the microscope reveals a world rival- 

 ling in beauty and infinity of extent the outer world 

 that is open to our unaided vision; and this instru- 

 ment can be used in the city as well as in the country, 

 and in winter as well as in summer. 



Another thing you of the city can do, is to suspend 

 seeds in bottles over water, and study the growth of 

 different plants as the tiny leaves unroll: Make neat 

 cases also for insects or minerals, and exchange them 

 for specimens. Collect specimens of veneers from 

 cabinet and piano shops, and prepare them for ex- 

 change. Nearly all the grains, and nuts, and spices, 

 and fabrics, and seeds, and barks, and woods, and 

 metals, can be found in city shops, and for these you 

 can readily get anything you may wish from the coun- 

 try. Again, many of you have books or pictures on 

 subjects of natural history which are old to you, but 

 which some member of the Association would be very 

 thankful to get. These also can be exchanged. 



Besides these things, we need only mention birds' 

 nests abandoned in leafless trees, cocoons suspended 

 from bushes and tucked away under fence-rails, beetles 

 burrowing in old stumps, sections of wood and bark, 



