The following (from "The New Jerusalem: The Extraordinary True Story of how a Secret Society Rebuilt London", Adrian Gilbert, pages 356-362) provides the context of Charles Piazzi Smyth. These pages might also facilitate a better understanding of Charles Taze Russell’s interest in the dimensions of the Great Pyramid.
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The development of Victorian Britain as the first great power of the industrial age went hand in hand with the growth of the British Israel movement. As we have seen, as far back as the late middle ages there had been a belief, at least in royal circles, that the British were descended from the lost tribes of Israel. During the nineteenth century these ideas were to be developed from amorphous traditions into a systematized creed. The first prophet of what, to his critics at least, seemed like a new religion was a Scot from Kilmarnock named John Wilson. He commenced his work of evangelizing the nation in 1837 - the same year that Queen Victoria ascended the throne. The following year he began lecturing at the Witness Hall in Aldersgate Street, London. Two years later, in 1840, he published a book, “Our Israelitish Origin”, based on these lectures. It was hugely successful and in 1874 the 'Anglo-Israel Association' was founded, holding its meetings in Wilson's house near St Pancras.
Wilson's message, that the British were descended from the lost tribes of Israel and that this could be proved from the Bible, was in tune with the mood of the period. ...
The British Israel torch lit by Wilson was eagerly taken up by another evangelist for the cause, Edward Hine. A younger man than Wilson, he attended the latter's lectures in his youth and wrote what was to become a best-seller on the subject: "Forty-seven Identifications of the British Nation with the Lost House of Israel, Founded upon 500 Proofs". This remarkable book, which went into enormous detail in analysing the Bible for texts supportive of the identification of the descendants of the lost Israelites with both the Celts and the Anglo-Saxons, sold over 416,000 copies. To put matters on a firmer footing, Hine also began to publish a monthly journal entitled "Life from the Dead". This was followed by a further magazine, "Leading the Nation to Glory", the name of which was later changed to "The Glory Leader". ...
As well as proselytizing in Britain, Hine lectured in America and Canada, where he found equally keen audiences. … The discovery that this new nation was none other than the most recent incarnation of the tribe of Manasseh (Britain was identified as the tribe of Ephraim, Manasseh's brother) did not strike people as incredible. ...
Another prominent British Israelite was Charles Piazzi Smyth, then the Astronomer Royal for Scotland. He too had attended some of Wilson's lectures and was convinced of the truth of what he heard because it chimed with another passion of his: pyramidology. The origins of this movement, which for a time ran in parallel with British Israelitism before being virtually taken over by it, go back to the work of John Greaves and his 1638 survey of the pyramids of Giza....
John Taylor, editor of the "London Magazine", himself a skilled mathematician, computed that the perimeter of the Great Pyramid was exactly 36,653.76 British inches, which could compute to 36,600 pyramid inches - each pyramid inch being slightly shorter than the British measure. To Taylor this implied that the Great Pyramid had been intended to be a species of calendar, with each 100 inches of its perimeter representing one day. On this analysis a full circuit of the pyramid symbolized 366 days, or approximately a whole year. Though the Royal Society rejected his paper on the subject, Taylor published his results in 1864 in a booklet entitled: "The Great Pyramid: Why Was It Built? & Who Built It?"
Like others of his time, John Taylor was deeply influenced by the Bible and the apparent need to attribute knowledge relating to measures to divine influence. He died the same year that his book was published but his mantle was quickly taken up by Charles Piazzi Smyth, who had been in correspondence with him for some months prior to his death. Shortly afterwards Piazzi Smyth made his own survey of the pyramids, finding further proof that the Great Pyramid was designed not just as a calendar but as an almanac of the ages. He believed that the lengths of its internal corridors, as measured in pyramid inches, mapped out the course of world civilization, with each pyramid inch representing one year. The role of Britain as 'Israel' was read into the measures of mute stones, especially the Great Step at the top of the pyramid's Grand Gallery. Summing up how the Grand Gallery symbolized the Christian era and the ascent of true Christians to the light represented by the messiah, Smyth felt able to write in all seriousness:
"And who are more particularly, the great national body of these rising, improving, and we may trust approved Christians?
"Some will claim the Church of one nation, and some another; some will argue for spiritual Israel, whether spread among Teutonic people, or mainly confined to the British Isles and America. And who shall decide amongst them?
"None but the Great Pyramid itself. Advance we, therefore, to the great step of 1813 A. D. (i.e. at 1,813 Pyramid inches from the North, or Christian nativity, beginning) of the Grand Gallery, and inquire there what is signified.
"The step marks there, by that date, the most energetic advances made by Great Britain in its latter-day spread of the Bible, and its latter-day preaching of Christianity to all the world. . .
"What manner of people, then, ought not we of Great Britain now, of Israel in ages past, to be at this juncture of our eventful history; saved above all nations by the providence of God in a manner we have never deserved, and for divine purpose in the future, respecting which nothing but the glorious Scriptures of Inspiration can give us any sufficient or saving idea; a halcyon time, when Ephraim shall be united once more with Judah, and both shall be on the Lord's side."
Today, given the prevailing scepticism of modern society concerning the existence of God, it is difficult to appreciate the powerful influence the idea that they were really Israelites in disguise had on Britons of the mid- to late nineteenth century. For very many people this was a plausible explanation for the extraordinary providence shown by God to Victorian Britain which gave them a standard of living to be envied throughout the world. It also gave them a sense that building the empire was a national duty, for in this way, in accordance with God's wishes, the Gospel could be carried to all corners of the world.
Smyth's choice of 1813 for the start of his 'great step' had as much to do with his appreciation of recent history as with pyramid measurements.
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The following is provided on the rear of Gilbert's book:
In 1666 the Great Fire ravaged much of the capital. After the flames had been put out and the dead buried, London was once more a blank canvas for builders and architects to create a new city - a city which could be rebuilt to reflect its glorious destiny.
For most of the men at the centre of London's reconstruction, including Sir Christopher Wren, were members of the Rosicrucian-founded Royal Society and believed in the mystical wisdom of the ancient world and the millenarianist beliefs of its founders. They were convinced that London had long been the chosen site of the New Jerusalem - the city that would descend from the sky at the second coming as foretold in the Book of Revelations.
In this eye-opening book, Adrian Gilbert, author of "Signs in the Sky", exposes a hidden London, revealing the true significance of such well-known sites as St Paul's Cathedral, the Monument and Temple church. He also introduces us to the men and women who shaped seventeenth century London according to their own beliefs. Combining detective story, archaeological investigation and historical insight, "The New Jerusalem" is a colourful historical portrait of London as we have never seen it before.