This book is the result of several years of research, in which time I have accumulated a long list of obligations for helpful suggestions too many to enumerate here. I must, however, mention the following: Dr. George A. Clarke, of the Observatory, King's College, Aberdeen, Scot land; Colonel Ernest Gold, of London; Lieutenant Col onel Harold E. Hartney Charles Fitzhugh Talman, late learned librarian of the United States Weather Bureau; Dr. Charles F. Brooks, of Blue Hill Meteorological Observatory, and Colonel Henry L. Brittain.
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