There have been many calculations around, all based on the same starting point (7 times) but all providing a different year.
Piere Agier (1748 - 1823) => between 1838 and 1848
John Bacon, (1738 - 1820) => two dates: 1866 and 1926
John Gill (1690 - 1771) => 1866 ends 6000 years of human existence on earth
Abbrech Johan Bengel (1687 - 1752)=>1836
David Chytraeus (1530 - 1600) => 1866 day of judgement
(you may also want to check Newtons exposé on Daniel and perhaps his pupil James Ferguson has something to say about this.)
But why should any of these interpretations be right? In retrospect we know these people were wrong. JW will tell you that they were right because, and here they open the bible at Revelation 6 and read you the first verses about the horses of the apocalyps. Their theory is that the moment the crowned Jesus started to ride, he was follwed by war on earth, sickness and death and hunger. They quickly point out that as of Jesus enthronement in September/ October of 1914, we had war, disease (spanish flu) and hunger.
As a matter of fact ... the Great War started in August. Not October. This therefore on the surface seemingly nice theory false to pieces. As a matter of fact: any war is by definition followed by sickness ... thanks to the dead bodies lying all around and the mall nutrition that comes from broken down distribution and health care. Read the ilias and you will find the same spooky horsemen : Agamemnon as the king, followed by war on the Trojans (truly a great war by any definition; marvel at the numbers), the plague and death and hunger.
1919 is completely fictitious. The JW calculate 3.5 years since 1914 for Jesus to enter the temple hence march/april 1918. That was superficially looking the time in which the board members went to prison on justified charges of sedition, no not based on the book: Finished Mystery, but private letters sent to army men. The moment they were released, because there was no need for a retrial, it was felt to be of the same order as the Israelites went of from Babylon into their homeland in approx 537 BCE. They call this: the liberation from Babylon the Great. As strange it may sound, they really think they were liberated from false babylonian teachings (babylon the great being the world empire of all other religions except JW)
So they recon that Jesus needed 3.5 years to kick Satans butt out of heaven, and to sweap the floor of the temple for another year or so.
The Revelation Grand Climax book, chapter 29, page 200, paragraph 7,says in part:
In 1919 Jehovah’s people on earth began to announce “the word of the kingdom” with renewed zeal. (Matthew 13:19)
As matter of fact, this picture is not quite truthful. Ask any witness about Cedar Point Ohio: the assembly where the call for publishers was made. That was 1922. Not 1919. They still used the cross, celebrated Christmas and birthdays and easter, and believed Jesus had been enthroned in 1874. It was not untill 1943 that the issue was put to bed and 1914 was the date to believe Jesus was invisibly present.
What else did they teach? Well... today Jw's will say the Faithful and descrete slave was chosen by Jesus in 1919 for dispensing meat in due season. (eh... any witness that does not know this scripture by heart should be DF-ed!) What then did they dispense? Note the points right after 8:3
Gods sole channel of communication was the WBTS and was used as such since 1879 ..... Gods sole channel of communication had no need to be chosen again, they claimed to have been functioning as such. On top they dispensed the believe that Jesus had already been enthoned in 1874. And this believe was maintained till 1943. Over a period of 60 years as Gods sole channel of cumminication they dispensed horseshit for meat in due season. I'm sure their heavenly master was glad to represented so truthfully.
On page 845 they taught this:
Also in the year 1918, when God destroys the churches wholesale and the church members by millions, it shall be that any that escape shall come to the works of Pastor Russell to learn the meaning of the downfall of "Christianity