The first and second editions of this work, consisting of five thousand copies, were sold in less than a year from the time of its publication. Encouraged by the rapid sale of the work, I now publish a third edition with a new preface which includes a letter from my old master. He certifies that I am a slave.
W. W. B.
This work is in the public domain in the United States because it was published before January 1, 1929. It was adapted by the Observatory from a version produced by Wikisource contributors.