The early history of the Tompkins clan, as written by Robert Tompkins, is a fascinating historical collection of ancestry. There are stories of kings and conquerors, saints and witches, as well as an exhaustive listing of Tompkins names and their relationships to each other, all indexed.
The Clan Of Tomkyns was written by Robert A. Tompkins in 1957 as an update to his book The Tomkins-Tompkins Genealogy which was published in 1942. Unfortunately, he died before being able to publish The Clan.
The original manuscript is located on the bottom level of the Central branch of the Los Angeles Library. It is located in the closed stacks, so you'll have to ask for it. It is listed in the card catalogue, which is online at http://www.lapl.org/.
Please note that The Clan contains very few specific source references, making it extremely difficult to determine where the author got his information. Quite a number of mistakes have been found in this work by later researchers. However, it does represent a much, much later version of The Tomkins-Tompkins Genealogy. Read all about The Clan of Tomkyns, a Lost, Now Found, Treasure.