Event: Lady Alice discovers she is with child and the Greystoke's buy child provisions to take along to Africa.
Source: This date is stretchable and any date will be Burroughs friendly between late January or early February. This working date is provided by me based on the assumption that most women, during that time period, are approximately two months pregnant before they discover it.
Date: May 14, 1872
Event: Greystoke's set sail from Dover, England.
Source: In Tarzan Of The Apes the author states it is "on a bright May morning." No other dating is provided by him. A chronologist is left to guess the exact date. Picking a date is exactly that, a guess. For calendar dating this is a very important event, however, and a Burroughs friendly working date needs to be provided.
As mentioned earlier, Burroughs often inserted his family genealogy dates, family & friends names, etc. into his stories. Following the author's lead when we search the Burroughs genealogy to see if any memorable occasions occurred in May 1872 that we could use as a working date we discover that the author's brother, Frank, was born on May 14. Keeping with Burroughs tradition this working date is friendly with the provided descriptions and will work as good as any until something more concrete turns up.
Date: June 14, 1872
Event: The Greystoke's arrive at Freetown where they chartered the barkentine Fuwalda.
Source: "A month later." ERB-Tarzan Of The Apes.
Date: June 16, 1872
Event: On the morning of the second day aboard the Fuwalda Captain Billings shot Black Michael in the leg.
Source: "The morning of the second day," ERB-Tarzan Of The Apes.
Date: June 18, 1872
Event: On the fourth day aboard the Fuwalda Clayton came on deck that morning just in time to see the limp body of one of the crew being carried below by four sailors while the first mate stood glowering with a heavy belaying pin in his hand.
Source: "The second day after the wounding of Black Michael." ERB-Tarzan Of The Apes.
Date: noon June 19, 1872
Event: At noon the Fuwalda passed a British man-of-war.
Source: "The following day," ERB-Tarzan Of The Apes.
Date: June 20, 1872
Event: The Fuwalda mutiny.
Source: "The next morning," ERB-Tarzan Of The Apes.
Date: June 25, 1872
Event: The Fuwalda sights land and that night Burroughs mentions Lady Alice is with child for the first time.
Source: "On the fifth day following the murder of the ship's officers land was sighted." ERB-Tarzan Of The Apes.
Date: June 26, 1872
Event: The Greystoke's are put ashore with all their belongings and Clayton builds a tree shelter. That night the two seen their first Mangani.
Source: "Early next morning." ERB-Tarzan Of The Apes. "At night upon their first day upon land." ERB-Tarzan Of The Apes.
Date: June 27, 1872
Event: Clayton begins work on a one room cabin.
Source: The morning after seeing the Mangani, ERB-Tarzan Of The Apes.
Date: near the end of July 1872
Event: Clayton finishes one room cabin built of small logs about six inches in diameter and completely covered on the outside with four inches of mud. He had also completed a stone fireplace and chimney but had yet made a door or furnishings.
Source: "Took the better part of a month," ERB-Tarzan Of The Apes.
Date: August 14, 1872
Event: British warships search for the Fuwalda and find her wreckage on the shores of St. Helena.
Source: "Two months after the Greystoke's leave Freetown." ERB-Tarzan Of The Apes.
Date: August 27, 1872
Event: Clayton had hung the cabin door, completed the furnishings, and moved all their belongings inside.
Source: "By the end of the second month they were all settled," ERB-Tarzan Of The Apes.
Date: September 1, 1872
Event: A Mangani bull attacks Clayton while he is working upon an addition to the cabin. That night Lady Alice gives birth to a healthy son.
Source: This is an event that Burroughs choice not to share the date with us. "One afternoon while Clayton was working upon an addition to their cabin he was interrupted by a group of fleeing monkies," ERB-Tarzan Of The Apes. Therefore, any date provided is mere speculation, but we still need one if you want to have a chronology. As mentioned earlier the author inserted many dates and names from the Burroughs genealogy, so when a working date is needed I follow Burroughs' tradition, and also use the genealogy.
As you can see there will never be a way to obtain an undebatable date, but there is a way to obtain a Burroughs' friendly date. The author says the Greystoke's one room cabin was built, furnished and moved into by the second month. If Clayton begin work on June 27 that means the Greystoke's were well settled by August 27.
Once this project was completed it is very likely Clayton began the second addition almost immediately. "There is but one thing to do, Alice, and that is work. Work must be our salvation. We must not give ourselves time to think, for in that direction lies madness." ERB-Tarzan Of The Apes.
Since Clayton was cutting down a tree for building purposes when the Mangani bull attacked him, it is obvious the Englishman had just finished the first section of the cabin and was just at the very beginning stage of his secondary project. If any construction on a second edition to the cabin were underway Tarzan and the Porter party would have seen the remains upon their first visit.
When Tarzan, age ten, investigated his father's cabin years later nowhere in any of the descriptions does it hint of a semi-erected second room. Clayton's cabin is clearly described as having only one room. When the Porter party was beached, Tarzan age twenty, there is no hint of a semi-erected second room and the cabin is again clearly described as having only one room.
By this research it is evident that the Mangani attacked Clayton within a few days of his August 27 completion of the first addition. To provide a Burroughs friendly working date to this event we go to the author's family genealogy to provide a date Burroughs could have used as a source. That day is September 1st the author's own birthday.