[61] Jackson, The Four Ages, p. 52. London: Cadell and Davies, 1798. 8vo. [62] Jackson, The Four Ages, p. 90. Transcriber’s Notes Cover created by Transcriber and placed in the Public Domain. Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed. Simple typographical errors were corrected; occasional unbalanced quotation marks retained. Ambiguous hyphens at the ends of lines were retained. Spelling of non-English words was not reviewed. Text uses both “appreciate” and “appretiate”; both retained. Index not checked for proper alphabetization or correct page references. End of the Project Gutenberg EBook of Preliminary Discourse on the Study of Natural Philosophy, by John F. W. Herschel