Thomas W. Dixon, Jr. has studied and written about C& O subjects for many years. He organized and has served as president of the Chesapeake & Ohio Historical Society since its inception in 1969. He has authored or co-authored 18 books, mostly on C& O subjects and hundreds of magazine articles and pamphlets.Karen Parker is that rare kind of writer who has an outstanding professional background in the field necessary for accurate understanding of her subject (in this case physics and mechanical engineering). Her explanations are clear, concise and devoid of esoteric terms and written for those who enjoy understanding mechanical things, but who are not deeply conversant with steam technology and would like to know more.