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Volume 1631

Chronology For E. R. Burroughs' Venus Series

By Fredrik Ekman (

This article is an attempt to create an accurate chronology for the first four books in the Venus series by Edgar Rice Burroughs. It can be seen as a companion to my chronology for the Princess of Mars trilogy in ERBzine #507 and as a sequel to my article "Before Venus: Carson Napier's Background" in ERBzine #604. The final story in the Venus series, The Wizard of Venus, has not been considered here because there is a gap in time of unknown length between it and the previous book.

One may ask why a chronology like this is important. To me, the main reason is that all of Burroughs' fantasy worlds form part of a larger universe, fitting together like pieces in a jigsaw puzzle. Knowing how Amtor fits into this puzzle can help avoid disasters like the Tarzan/Carson of Venus comic book series that Dark Horse published in the 90's, which completely screwed up everything.

A chronology without dates would be a rather pointless thing to have. Pirates of Venus does not give the date on which Carson left Earth, but there are many clues that can lead us to assume a date. In my previous article I concluded a date of July 18, 1931, extrapolated from the initial events described in the novel. There are other possibilities. My article also mentioned April 18, 1931 as an option. Coogan and Power have argued for a date in June, 1928, presumably based on the reference to Von Horst (PV/1). Astronomical observations give yet other dates. The relative positions of Mars, Venus and the moon matched those described in the novel (PV/2) on September 16, 1930. On the other hand, Carson cites the distance to Mars as "thirty-five million miles" (PV/2), which suggests a very close opposition such as occurred on August 23, 1924. I have chosen to stay with my original premise, which seems to best fit the facts as we know them.

Not only the beginning date leaves room for doubt, but also the dates within the chronology relative one another. Burroughs was often vague, giving time periods such as "a few weeks" or "several days" between events. I have assumed that "a couple" always means two, that "a few" always means three and that "several" always means five. This frequently results in time periods that may be several days or weeks too long or too short.

In particular, there are two periods for which the duration is highly uncertain. One is the construction of the first anotar (see note 8 below) and the other is the enslavement under Tyros (note 13). Everything occurring between these two must therefore be taken with a healthy dose of scepticism. However, both occur before Betty Callwell's return to Earth (note 15), which gives us a fresh date on which to build the end of the chronology. As a result, the final date of the chronology should be correct within three or four days.

Time zones on Venus have not been taken into consideration. This is partly because Carson tends to move in a relatively narrow area along a north-south strip, so it would make very little difference either way. But mostly because the poor maps of Amtor make it impossible to pinpoint Carson's exact longitudal position at any given time.

Venusian Measurements of Time

Information about how the Amtorians measure time can mainly be found in two books in the series, Pirates of Venus and Carson of Venus, with some additional information in Lost on Venus. However, the sources are not completely consistent.

It seems certain that the Amtorian equivalent of our "month," called ax, is 20 Amtorian days long (CV/4). In its turn, the "Amtorian day consists of 26 hours, 56 minutes, 4 seconds of earth time" (PV/10, confirmed in CV/8).

But the sources disagree when it comes to how the day is subdivided. The Amtorian "hours" are called te, but it is not clear whether there are 20 in a day (PV/10) or 36 (CV/8, and confirmed throughout that book). The te in turn is divided into vir. Fifteen vir is "sixty minutes of earth time" (LV/16) and five vir is "a little over twenty minutes of Earth time" (LV/21). These figures best match the 20 te alternative, in which case there are 20 vir in each te. If the day has 36 te, then there must be 11 vir in each te, which seems unlikely. A possible explanation for the disparate numbers is that the length of the te varies from nation to nation.

The exact length of the Amtorian day is not without question either. Both the length of the te and the ax are specified, respectively as "80.895 earth minutes" (PV/10) for the te (suggesting 20 te in a day) and "slightly over twenty-two days, eleven hours of Earth time" (CV/4) for the ax. While these two citations are mutually compatible, they do not agree with the day-length cited above, indicating instead a length of approximately 26 hours, 57 minutes, 54 seconds. The difference between this and Burroughs' quote, less than two minutes, may seem of little consequence, but accumulates to a difference of over fifteen hours for some dates in the chronology.

In order to decide which length of day to use for the chronology, it would be beneficial to know where Burroughs' Venusian time measurements originate. Two possibilities present themselves. Either it was from an external source, or it was an invention of his own.

Today we know that the planet Venus rotates very slowly around its axis. So slowly that one solar day on Venus takes almost 117 Earth days, over half the Venus year. But in Burroughs' day, the thick cloud cover made any observations of the surface impossible, and many scientists believed that Venus had a day of similar length to those of Earth and Mars (most of the rest of the scientific community equally incorrectly believed that Venus always turned the same face toward the sun). It is possible that Burroughs' quoted day-length came from some such scientific hypothesis. I have examined a number of astronomical books that Burroughs may have had access to, including works by Flammarion, Arrhenius and Jeans, all of which Burroughs very likely consulted. To this date I have not found any presumed day-length that matches, or even approximates, that cited by Burroughs.

What if Burroughs invented the day-length himself? How did he arrive at his figures? A curious detail is that both the different day-lengths discussed above correspond to very nearly 200 Venus days for one Venus year. Perhaps Burroughs was looking for a nice and round figure for his Amtorian calendar? If so, how would he have calculated the length of his te? Perhaps he would start by converting the year into hours. The length of the Venus year was available in several books. Flammarion quotes it as 224 days, 16 hours, 49 minutes, 8 seconds in Popular Astronomy. Thus, Burroughs could calculate the number of hours in one year (224*24+17=5393). Next he would find out how many te there are in one year (200*20=4000). Then he would find out how many hours there would be in one te (5393/4000=1.34825) and multiply that by the number of minutes in one hour (1.34825*60=80.895). The result matches exactly the length he quoted for the te. Only by first rounding the number of hours in the year would he have arrived at exactly 80.895 minutes. Any other method would result in a decimal deviation.

Ergo, Burroughs came up with the length of the Amtorian day himself. So how did he arrive at his quoted length of day? I have not been able to verify this, but it is probably yet again a decimal error, or possibly an arithmetic error. With this in mind, I have made a decision to go with the 26:57:54 day, which is based on some of Burroughs' exact quotes and also very close to his actual intentions.

The Amtorian time units given by Burroughs are summarised below, assuming 20 te for each day. Note that the year given is a calendar year, not in exact correspondence with scientific observations.

  1 vir 4 minutes, 2.7 seconds
20 vir 1 te 80 minutes, 54 seconds
20 te 1 day 26 hours, 57 minutes, 54 seconds
20 days 1 ax 22 Earth days, 11 hours, 18 minutes
10 ax 1 year 224 Earth days, 17 hours, 0 minutes
In addition to these Amtorian units, Burroughs often used terms like "day," "week" and "month" without specifying whether these refer to Earth units, corresponding Venus units, or some mix of the two. What he does specify is that "for clarity, I shall translate [te] into its nearest earthly equivalent, hour, although it contains 80.895 earth minutes" (PV/10). Analogously it is reasonable to assume that "day" and "month" also refer to the Amtorian equivalents. However, Burroughs never mentioned anything about an Amtorian week. If one exists, it could be ten Amtorian days long, but since we do not know that it does, it is more logical to assume that one week in Burroughs' terminology is a hybrid of seven Amtorian days. Only once does Burroughs refer to a time period of "a year" (EV/55). See note 20 below for further discussion regarding this case.

About the Tables

The tables are divided into columns, each row giving Earth time (Gregorian date), Amtor time (years, ax and days since Carson's arrival) and a description of the event. I have usually only given one event per day. Some events also have numbers referring to notes with details about the event in question. All Earth dates are given relative Pacific Standard Time, which is what Carson probably used while still on Earth.

Between the time columns and the event column I have inserted a vertical line. The colour of this line is lighter when the time given is uncertain, usually in relation to the time given immediately above. It follows that darker parts of the line that are preceded by a light part are probably also uncertain by the same amount of time. For example, the take-off from Japal (note 16) is uncertain and may be one day later or earlier than specified. In consequence, the forced landing in Voo-ad may also be one day later or earlier, even though it is marked with the dark colour. (If you print this article, make sure to set your browser to print background colours, or this column will turn invisible.)

Pirates of Venus

Earth Time   Amtor Time   Event Note
August 18, 1931   0 years, 0 ax, 0 days   Advent upon Venus 1
August 19, 1931   0 years, 0 ax, 1 days   Meeting with Mintep  
August 29, 1931   0 years, 0 ax, 10 days   Planned advent on Mars
September 11, 1931   0 years, 1 ax, 2 days   First glimpse of Duare 3
September 17, 1931   0 years, 1 ax, 7 days   Fights for Duare in the garden  
September 18, 1931   0 years, 1 ax, 8 days   "Shaves" with hair removal salve 4
September 26, 1931   0 years, 1 ax, 15 days   Becomes tarel hunter  
September 27, 1931   0 years, 1 ax, 16 days   Gathering tarel  
September 29, 1931   0 years, 1 ax, 17 days   Brought aboard the Sofal  
September 29, 1931   0 years, 1 ax, 18 days   Cleans T-ray guns  
October 4, 1931   0 years, 2 ax, 2 days   The Soldiers of Liberty are formed 5
October 8, 1931   0 years, 2 ax, 5 days   Anoos is killed 6
October 9, 1931   0 years, 2 ax, 6 days   Mutiny aboard the Sofal  
October 9, 1931   0 years, 2 ax, 7 days   Boarding the Sovong  
October 13, 1931   0 years, 2 ax, 10 days   Boarding the Yan  
October 14, 1931   0 years, 2 ax, 11 days   Captured by Thorists 7
1. The day of arrival is quite clearly 31 days after take-off. If Carson left Earth in the evening of July 18 and if he managed to maintain the diurnal rhythm that he had when he left, then he reached Venus on the evening of August 18 (I have chosen to assume the time 9 p.m. PST).

2. According to Carson's original plan, arrival on Mars was planned "between forty and forty-five days" (PV/2) after take-off, which would set it about this time.

3. Carson mentions "the ensuing three weeks" (PV/4) but it is not clear whether that refers to the time before he first set eyes on Duare, or before he was freed from imprisonment. I have here assumed the former, since that gives a slightly less improbable time frame for learning the language and other things.

4. No indication is given regarding the time between this event and the former. I have guessed one single day.

5. No exact reference is given regarding the first time on board the Sofal. I have taken four days as a reasonable assumption given the distance travelled.

6. It is not clear whether Anoos was killed immediately after all the "KKK" members had been recruited, but such has been my assumption.

7. The concluding events in the novel must occur before November 6, 1931, the date that Burroughs finished writing the book.

Lost on Venus

This chronology is based on the paperback edition of the novel, which in turn is based on the original magazine edition. The hardback edition was revised and may differ in some details.
Earth Time   Amtor Time   Event Note
October 14, 1931   0 years, 2 ax, 11 days   Brought to Kapdor  
October 15, 1931   0 years, 2 ax, 11 days   Escape from Kapdor  
October 15, 1931   0 years, 2 ax, 12 days   Captured by nobargans  
October 17, 1931   0 years, 2 ax, 14 days   Basto fights tharban  
October 23, 1931   0 years, 2 ax, 19 days   Reaches valley  
October 25, 1931   0 years, 3 ax, 1 days   Visiting Skor's castle  
October 26, 1931   0 years, 3 ax, 2 days   Escape from Skor's castle  
October 28, 1931   0 years, 3 ax, 3 days   Meets Ero Shan and enters Havatoo  
October 29, 1931   0 years, 3 ax, 4 days   Becomes a citizen of Havatoo  
November 3, 1931   0 years, 3 ax, 9 days   Enjoys Havatoo with Nalte  
November 4, 1931   0 years, 3 ax, 10 days   Explains aircraft to Mohar  
November 21, 1932   2 years, 0 ax, 10 days   Nalte is kidnapped 8
November 22, 1932   2 years, 0 ax, 11 days   Escape from Kormor  
November 23, 1932   2 years, 0 ax, 12 days   Escape from Havatoo  
8. How long does it take to build an aircraft? Carson had no want for help, but had to build it from scratch and give astronomy lessons as well. It seems logical to assume considerably less than two Venus years (400 days), since Carson apparently only witnessed one of the annual war games (LV/16). It must on the other hand have been at least several ax, given that he seems to have attended several of the monthly games. My guess here is that the construction took seventeen ax (340 days). It is possible that my guess is incorrect and that the period should be significantly shorter. The relatively long passage of time was chosen in order to match Betty Callwell's return to Earth (see note 15) and to minimize the enslavement at Tyros' court (see note 13).

Carson of Venus

Earth Time   Amtor Time   Event Note
November 24, 1932   2 years, 0 ax, 13 days   Duare captured by warrior women 9
November 25, 1932   2 years, 0 ax, 14 days   Escape from Houtomai  
November 26, 1932   2 years, 0 ax, 15 days   Take-off in search for new lands  
November 28, 1932   2 years, 0 ax, 17 days   Lands in Sanara  
December 21, 1932   2 years, 1 ax, 17 days   Sent on secret mission  
December 22, 1932   2 years, 1 ax, 18 days   Leaves for secret mission  
December 23, 1932   2 years, 1 ax, 19 days   Meeting with Zerka  
December 24, 1932   2 years, 2 ax, 0 days   Enters service as Zani guard  
January 2, 1933   2 years, 2 ax, 8 days   Invited to Zerka  
January 3, 1933   2 years, 2 ax, 9 days   Appointed duty at the Gap kum Rov  
January 11, 1933   2 years, 2 ax, 16 days   Torko leaves Carson in charge  
January 16, 1933   2 years, 3 ax, 0 days   The execution of Kord  
January 20, 1933   2 years, 3 ax, 4 days   Carson finds Mintep
January 21, 1933   2 years, 3 ax, 5 days   Narvon is arrested  
January 23, 1933   2 years, 3 ax, 6 days   Escape from Amlot  
January 24, 1933   2 years, 3 ax, 7 days   Sets sail to rescue Mintep  
January 25, 1933   2 years, 3 ax, 8 days   Captured by Zanis  
January 26, 1933   2 years, 3 ax, 9 days   Escape once again from Amlot  
February 7, 1933   2 years, 4 ax, 0 days   Return to Sanara  
February 8, 1933   2 years, 4 ax, 1 days   Rescue of Nna  
February 14, 1933   2 years, 4 ax, 6 days   Sets sail for Vepaja 11
February 21, 1933   2 years, 4 ax, 13 days   Taken aboard the Nojo Ganja  
February 23, 1933   2 years, 4 ax, 14 days   The rescue of Duare 12
9. When Lost on Venus ends it is night, yet as Carson of Venus begins immediately after, it appears to be daylight. Had they been flying through the night they should have come further. I simply assume that they flew around looking at scenery for a few hours.

10. This date and the one preceding are problematic. We know neither how long Torko was away, nor when the execution of Kord was carried out. At the very least, Carson must have been in charge for several days before he found Mintep. My guess here is at eight total.

11. There is no reference whatever to how long it took to prepare the boat for the long voyage.

12. In what appears to have been but a few hours, Carson was walked from the harbour to Kooaad. Yet, judging from Burroughs' map of Amtor, Kooaad is at least 100 miles from the coast.

Escape on Venus

Earth Time   Amtor Time   Event Note
February 24, 1933   2 years, 4 ax, 15 days   A glimpse of sunlight  
February 25, 1933   2 years, 4 ax, 16 days   Captured by Myposans  
February 26, 1933   2 years, 4 ax, 17 days   Carson kills a guard  
February 27, 1933   2 years, 4 ax, 18 days   Sold as slaves  
February 28, 1933   2 years, 4 ax, 19 days   Fight with guypals  
March 1, 1933   2 years, 5 ax, 0 days   Given as a gift to Tyros, the jong  
July 24, 1933   3 years, 1 ax, 8 days   Called before Tyros 13
July 25, 1933   3 years, 1 ax, 9 days   The death of Tyros  
July 26, 1933   3 years, 1 ax, 10 days   The rescue of Kandar and Artol  
July 27, 1933   3 years, 1 ax, 11 days   Arrival at Timal  
July 30, 1933   3 years, 1 ax, 14 days   Jantor is killed  
July 31, 1933   3 years, 1 ax, 15 days   Brought down outside Japal  
August 1, 1933   3 years, 1 ax, 16 days   Imprisoned in Japal 14
August 26, 1933   3 years, 2 ax, 17 days   Escape from the dungeon  
August 26, 1933   3 years, 2 ax, 18 days   Captured by Brokols  
August 31, 1933   3 years, 3 ax, 2 days   Entry into Brokol  
September 23, 1933   3 years, 4 ax, 3 days   Meeting with Loto-El-Ho-Ganja  
September 24, 1933   3 years, 4 ax, 4 days   Loto's disappearance discovered 15
September 25, 1933   3 years, 4 ax, 5 days   Take-off from Japal 16
October 3, 1933   3 years, 4 ax, 12 days   Forced landing in Voo-ad  
October 6, 1933   3 years, 4 ax, 14 days   On display in the museum  
October 7, 1933   3 years, 4 ax, 15 days   Conversation with Vik-yor  
October 11, 1933   3 years, 4 ax, 19 days   Vik-yor refuses to free Carson 17
October 14, 1933   3 years, 5 ax, 1 days   Duare escapes with Vik-yor  
October 15, 1933   3 years, 5 ax, 2 days   Duare rescues Carson and Ero Shan  
October 16, 1933   3 years, 5 ax, 3 days   Shot down by Falsans  
October 17, 1933   3 years, 5 ax, 4 days   Arrival at Hor  
October 18, 1933   3 years, 5 ax, 5 days   Enlists in the Pangan armed forces  
October 29, 1933   3 years, 5 ax, 15 days   March for Hangor starts 18
October 31, 1933   3 years, 5 ax, 17 days   Captured by Hangor soldiers 19
November 1, 1933   3 years, 5 ax, 18 days   Taken before Jeft  
November 3, 1933   3 years, 5 ax, 19 days   Meeting with Duare  
November 4, 1933   3 years, 6 ax, 0 days   Escape from Hangor  
November 5, 1933   3 years, 6 ax, 1 days   Banat is left at Hor  
November 6, 1933   3 years, 6 ax, 2 days   Rescuing one of the Cloud People  
November 9, 1933   3 years, 6 ax, 4 days   Out of the clouds 20
13. "The days dragged on" (EV/14) is the only indication of time passing before this incident. That could mean months, or it could mean just a few days. Due to the considerable uncertainty, this and the following dates have been calculated backwards from Betty Callwell's return to Earth (see note 15). The resulting period of more than six ax seems long, but is a necessary assumption in order to match the return to Sanara (see note 20).

14. Both this event and the meeting with Loto-El-Ho-Ganja below are said to be "a couple of weeks" after the preceding event (EV/23 and EV/25). Unlike other similar instances, I have here assumed a couple to correspond to three, in order to shorten the time spent as Tyros' slaves (see note 13).

15. Betty Callwell was found early in the morning of September 24 (EV/29), but no year is specified. The date given in the table has been based on the assumption that she was found about 8:30 a.m. EST (5:30 a.m. PST). Dates immediately preceding have been calculated backwards from this date (see note 13). Other assumptions of uncertain dates prior to this one must also be made with this date in mind (see in particular note 8), and by compressing them it is in fact possible to assume that Betty Callwell's return was in 1932, but then the return to Sanara will be incorrect (see note 20). It has been theorised by other fans that the date is in 1940, just before Burroughs wrote the story. Indeed, this may have been Burroughs' intention, but the chain of events described in this chronology belie that possibility.

16. Carson and Duare took off "as soon as we decently could" (EV/30). Presumably they stayed at least over night in Japal.

17. The exact number of days here is uncertain, but not too many. I have randomly guessed at four.

18. The order to march for Hangor was given "about ten days after our arrival in Hor" (EV/48), and the actual march started on the day following.

19. Burroughs does not say how fast the lantars are, but assuming 15 mph, the march to Hor (450 miles) should take about a day and a half. Carson and Ero Shan were captured yet another day later.

20. Carson estimates that they "had been gone a year or more" (EV/55), but my calculations indicate less than nine Earth months. It is possible, however, that Carson refers to a Venus year, and indeed he was gone from Sanara for about one Venus year and two ax. This assumption requires a relatively long period of enslavement at Tyros' court (see note 13).

The Excel Spreadsheet

The above tables have been produced using an Excel spreadsheet. If you disagree with my assumptions, or if you just want to play around with different values, then you will want do download this document.

Here is how to use the document:

  1. Download the Zip file
  2. Unpack the Zip file using Winzip or some similar tool.
  3. Open the document VenusChronology.xls and enjoy the experience!


I would like to extend my thanks to John Tyner II and Thomas Gangale for kind help with the research for this article.


References in the text are given with title abbreviation and chapter number. The following stories by Edgar Rice Burroughs have been referenced:
  • Pirates of Venus [PV]
  • Lost on Venus [LV] (paperback edition)
  • Carson of Venus [CV]
  • Escape on Venus [EV]
  • The following sources by other writers have also been used:
  • Peter Coogan and Dennis Power, Burroughing Beneath the Page: The Life of Matthew Nicholas Carter
  • Fredrik Ekman, "Before Venus: Carson Napier's Background", ERBzine #604
  • Camille Flammarion, Popular Astronomy, trans. J. Ellard Gore, D. Appleton and Company, circa 1894
  • NASA, Venus Fact Sheet


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