Edmund Beckett, 1st Baron Grimthorpe
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Edmund Beckett, 1st Baron Grimthorpe, Q.C. (12 May 1816 – 29 April 1905), known previously as Sir Edmund Beckett, 5th Baronet and Edmund Beckett Denison was a lawyer, amateur horologist, and architect. In 1851 he designed the mechanism for the clock of the Palace of Westminster, responsible for the chimes of Big Ben.
He was born at Carlton Hall Nottinghamshire, England, and was the son of Sir Edmund Beckett, 4th Baronet. He studied at Eton and Trinity College, Cambridge, was made a Queen's Counsel in 1854, and was created Baron Grimthorpe in 1886. He is sometimes known as Edmund Beckett Denison; his father had taken the additional name Denison in 1816, but the son dropped it on his father's death in 1874. He married Fanny Catherine (23 February 1823 – 8 December 1901), daughter of John Lonsdale, 89th Bishop of Lichfield. He died on 29 April 1905 after a fall, and is buried in the grounds of St Albans Cathedral.
A Rudementary Treatise On Clocks Watches & Bells For Public Use 1903
By Edmund Beckett
The following is an excerpt from the Treatise where Edmund Beckett talks about a “Single-Pin Escapement”
“Single-pin escapement.—This very simple and neat-looking escapement has been several times re-invented. But I believe the only person who ever made it really succeed, from better attention to the proportions, was the late Mr. C. Macdowall, a very ingenious clockmaker, who died in 1872 at the age of eighty-two. There is an interesting memoir of him in the Horological Journal of Sept. 1873. But, like many other uneducated inventors, he was very difficult to convince that an independent inventor is not allowed by the world the credit of a first inventor unless he is so. He also invented that most useful instrument—the spiral drill; or rather I should say, he invented the practical mode of making it by twisting a piece of pinion wire, for the thing itself turned up in wood as an old Indian invention in the 1851 Exhibition.
Another of his independent inventions was the ‘helix lever wheels,’ as he called them, but they also appeared in some German clocks in the same Exhibition; besides some other things which had been published in well known English books.
He also persuaded himself somehow or other, that he invented the three-legged escapement which I shall next describe; but no one ever saw or heard of it until it had been made from my design, though he had shown me all his inventions, and I had helped him to get both a patent and an Exhibition medal for his single pin escapement, and old Mr. Dent, under my advice, had bought the patent for a considerable sum, and gave him an order for 500 watches on that plan if he could make or get them made, which he could not; and Mr. Dent accordingly got some made in Switzerland. I wore one of them long enough to see that it answered very well, but the expense of the two extra wheels which it requires overbalanced the advantages, though I hear they have been also made in Paris from Macdowall’s instructions, the patent not having been taken there, and being perhaps difficult to maintain here if it had been disputed; for the thing had certainly been published, as we found afterwards in a French book.
Its action is evident enough from this picture (fig. 16). It has the advantage of giving a great part, you may practically say half, of the impulse directly across the line of centres (of the wheel and pallet arbor) and therefore with very little friction. The pin is made of a ruby, and should be set very near the arbor. The older ones were put too far off. Macdowall made them with a ‘neck-bearing,’ i.e. the pivot was behind the wheel, or the arbor came through the frame, and had the wheel pinned or squared onto it. The pallet piece itself forms the crutch for the pendulum, the scape-disc being set behind the clock frame. It should have eccentric fork-pins to adjust for beat.”
I have found some additional information on this Single Pin Escapement. It was patented by Mr. C. Macdowall in 1851. The following passage has been copied from The Encyclopaedia Britannica of 1878.
The escape turns one revolution each two ticks. In order to keep the gearing reasonable I’ve opted for a long therefore - 1 1/2 second pendulum.
The excel spread sheet is calculated for a 1 1/2 second pendulum and the Great Wheel turning once per hourl
This is the escapement and the little shape in the very center of the object will carry a 1/8” single pin that is the escapement.
The first trial drawing provide for a 5.7º swing which may be too large. The escape pin is 1/8” and is 1/4” off center.
The little pinion on the left is the escape pinion which needs to turn once every three (3) seconds with a 1 1/2 second pendulum. the wheel is 12:1 so turns once every 36 seconds
The ratio on the next wheel is 10:1 and so turns once every 6 minutes. At this stage each the wheel has 120 teeth and each pinion 12 leaves giving a 10:1 ratio at each stage.
Again a ratio of 10 to one has this wheel turning once every 60 minutes and can carry the minute hand and a drive drum of 30 wraps will give a 30 hour clock.
The plates have five arbors counting the pendulum arbor. The chosen shape has nothing to do with function only asthetics. Both plates are drilled at once to ensure alignment of holes.
The plate pattern comes from Turbo Cad and the escapement drawing is shown here although it will ultimately go behind the plates
This is the third wheel and the teeth are very fine to be made in wood and the wheel center has to be carefully drilled.
The second wheel is directly opposite the third wheel and in fact could engage the escape pinion if it were not for the spacers
The great wheel is also the hour wheel and is placed on the center line of the plates. No thought has been given the time train at this point.
The over ration is 1200 : 1 in order to go from once per hour for the great wheel to once in 3 seconds at the escape.
At this point I am concerned about the size of the teeth - they are about 1/8” from tip to gullet and that doesn’t allow for much error in centering the arbor.
The typical spacers are at the corners and will contian 1/4” bolts in their centers. I don’t need a bolt this thickness but there is a better selection in 1/4” size.
Originally the dowels were intended to keep things aligned, but as it turned out they were not necessary.
The top angle shaped spacers will keep the clock rigid in all directions and avoid future binding problems.
The plate spacers are in position and glued together. By using multiple pieces of ply, both the stacked thickness and the parallel surfaces are maintained.
The top plate its slipped on the bolts.
The escape pinion is the first one located and drilled. The succeeding arbors are depthed on the plates, punched with a pointed pivot and drilled.
By laying out the gears in a general “tee” shape - the spokes of all three wheel are overlain giving the desired appearance.
The front view of the clock will show the works in front of the pendulum.
I have put an experimental escapement on the movement at the test bench just to see what needs to be done
The little pendulum is not the final it is just a short light piece of wood because I’m not working on “keeping time” at this point.
This tries to duplicate Edmund Beckett’s sketch
Hanging on the wall between pool cues and the book shelf it takes up floor to ceiling.
Still needs the time train but that can wait for awhile
A simple face and hands to go with a simple escapement
For a video look: