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Antique Clocks Blog Home → Viewing post: "John Topping Equation of Time Clocks"

John Topping Equation of Time Clocks April 1, 2014

Daniel Clements – www.pendulumofmayfair.co.uk

I have had the pleasure to come across this amazing early 18th century ‘equation of time’ clock by John Topping of London. John Topping is not a household name in today’s clock world but he really should be. He built some of the most fantastic complex antique clocks during his time working in London.

He started as an apprentice to William Grimes in 1691 and he worked up until his death in 1747. He always described himself as ‘Memory Master’. I am not sure if this was a honour bestowed on him or if it was like a sales and marketing slogan for him in the 18th century, either way he produced some exceptional clocks.

Further details of month duration ‘Equation of Time’  John Topping Clock.

Figure 1: Equation of Time John Topping Clock C1730

The clock above is a fine example by John Topping, a superb early 18th century antique clock manufacturer in London. It is a most desirable combination of a superb and interesting complex movement and a beautiful veneered walnut cabinet. The dial is 12 inch and is signed to a recessed triangular sector, ‘John Topping Memory Master.’  The dial is of a specific elongated dimension to fit the extra large seconds and the rise and fall of pendulum and strike/silent dials to the arch.

If you continue down from where the makers name is signed and above the six o’clock position on the dial, you will see a revolving year calendar. On this year calendar there is an equation table allowing you to set ‘true time’ in the 18th century. I will come to what ‘true time’ is later in this piece. The top line of this year calendar is engraved ‘Sun Slower’ or ‘Sun Faster’, the next line gives the months divided into days which are numbered 5,15 etc for each month. The equation and calendar dial is set by a winding square next to the 60 and midday position on the clock.

You will notice that the winding holes are located above the centre position rather than below centre on most clocks, this allows enough room for the equation of time year calendar ring. The thin blued iron strip marks the day of the month and then  so many minutes faster or slower than a sundial can be read off for calculating actual time. The dial has superbly matted centre, chapter ring, specifically made spandrels and engraving to small sections within the arch.

The seconds feature to the arch is large which is a really nice feature. It also has a sunburst feature cut in the dial to the top centre section. A superbly laid out and designed dial by this wonderful clockmaker. In the picture below you will see how complex the movement requires to be in developing a dial like this.

The movement has a brass centre section and two side sections. From the picture above you can see the cam which lifts and lowers the pendulum for small adjustments to time. You can also see the many pillars used in this high quality movement.

18th century ‘Equation of Time’ table

 

The table above was sometimes pasted inside some special London clocks when they did not have a proper year calendar, so the owners could work out the calculation manually. Clearly full year calendar equation clocks are exceedingly rare and most likely cost a huge amount of money, as such probably only a very small amount of these clocks were ever manufactured.

So what is ‘true time’ then ? In the 18th century finding out what midday was was relatively easy, a sundial could be used. The problem comes as this is not ‘actual time.’ As a result of the elliptical rotation of the earth, clocks were sometimes slower or sometimes ahead of this sundial time. A good explanation and for the science minded of us can be found on the Wikpedia Equation of Time Page.

Daniel Clements

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