Solar Additions Sunwings: The Harrowsmith Guide to Solar Addition Architecture, by Merilyn Mohr. Camden East, Ontario: Camden House Publications, 1985. (Available in the U.S. from Harrowsmith USA, Charlotte, VT. 05445.) 146 pages, $14.95 paperback. by Paul Hanke Harrowsmith is a fine Canadian magazine that now is venturing into the U.S. market with a south-of-the-border edition. The magazine has a well-deserved reputation for quality, but this book doesn't live up to the precedent set by the periodical. The photos too often are murky, the drawings have an amateur quality, and the text is written primarily for home owners. Occasional terms also may need translation for those who do not regularly tune in to the Canadian Broadcasting Corporation. Those who have kept up