National Geographic : 2009 Sep
the commercial beneﬁts. Imagine the increased amenity to our living spaces as we could grow apples, pears, honey, and rice on our roofs whilst we enjoy a glass of our favorite tipple—and the fantastic skylines of our cities. Absolutely fabulous! EDDIE SMITH London, England Using a two-page photograph of Chicago’s City Hall roof garden to launch your article is a perfect example of image over substance. Here is a city of nearly three million people that has never had—and is still far from—a working recycling program. A city that still favors cars over public transit. The second irony in the photo is the slanting-glass Thompson Center building shown to the left of City Hall. When it opened for business, the sun made it so hot that employees set beach umbrellas over their desks until the air-conditioning was upgraded and turned to high. BILL WADE Chicago, Illinois Flat roofs in humid climates have always been a bad idea. But there are simpler ways to accomplish the goals: permeable pavers, regular sloping roofs that are insulated enough to hold a blanket of snow in winter, rain barrels and cisterns, fewer lawns, and more areas of native-plant ecosys- tems. And no-tech “green roofs” continue to be practicable. In Midewin National Tallgrass Prairie the remaining ammo bunkers of the former Joliet arsenal have their sloping sides of reinforced concrete covered with soil and local native grasses, just like the earth lodges of the tribes of the upper Missouri River that Lewis and Clark visited. JEAN SMILINGCOYOTE Chicago, Illinois I would think it counterproduc- tive to grow much of anything on roofs that are ten-plus stories high. Imagine the difﬁculties of getting water, fertilizer, et cetera up to the plants—plus the air pollution. PHILLIP TUTTLE Carthage, Illinois Copyright © 2009 National Geographic Society All rights reserved. National Geographic and Yellow Border: Registered Trademarks ® Marcas Registradas. National Geographic assumes no responsibility for unsolicited materials. Printed in U.S.A.