8. Strutt Epicyclic Skeleton ClockSKELETON CLOCKS
For many centuries, mechanical clocks were the most accurate, and perhaps the most common, of measuring instruments. Some of the greatest physicists of all time, like Galileo, Hooke, and Huyghens, were involved in their development, and their commonness should not diminish our appreciation of their importance in Science and Industry. Over the same period, clock- and watchmaking technology has often opened the way to improved construction of other instruments. Even in 1960, the operation of the first laser was made possible by the ready availability of synthetic ruby developed for the 'jewels' in watches.
In the late eighteenth and early nineteenth century the art of mechanical clockmaking reached its zenith, but few examples are to be found in Queensland. One particularly interesting genre is the 'skeleton clock' where superfluous material is cut away, allowing a clear view of the mechanism.
This virtual gallery showcases the work of a retired Science teacher who has constructed over 50 mechanical clocks. Some are based on published designs but many have been reinvented from book and catalogue photographs of rare prototypes. Note that these clocks are not actually on display in the Physics Museum, but more photographs will be added to this page in the future.
Click on the images to see enlarged views.
8. Strutt Epicyclic Skeleton Clock
This is a copy of the original clock made in 1830 by Strutt and Wigston.
Unfortunately, because of the complexities involved in epicyclic gears and the consequent high cost of manufacture, very few clocks were produced by the original makers.
However, the design has been copied many times during the last century both commercially and by amateur horologists.
Its attraction lies in the challenge and technical difficulties to be overcome in cutting the epicyclic wheels.
One hundred such clocks were made between Nov. 1973 and Feb 1974 by E. Dent & Co., and sold mainly in the United States for some $3500 each.
9. Scissors Clock
This clock is so named because the motion resembles the action of a pair of scissors.
It employs the version of an escapement invented in 1735 by J.B. Durertre for use in ships at sea.
The action of gravity on one pendulum bob is counteracted by that on the other, so that the clock continues to run without being in a level and stable position.
There are two pallet arbors each with a single pallet. At the rear end of each arbor is a pinion meshing with the other; on each arbor a pendulum is fixed, the bobs are skeletonised as are the counterpoises.
A similar clock is in the Henry Ford Museum, Dearbon, Michigan, U.S.A.
12. The Merlin Band Clock
The original clock was made by James Merlin in 1776. It is now in a private collection in England.
Unusual technical features of the clock include a dead-beat verge escapement with a crown-wheel of sixty teeth, while the connection between the verge arbor and the centre wheel is by means of a worm pinion.
As far as is known, this clock is only the third copy ever made.
16. Scott Battery Electric Clock
These clocks were invented by Herbert Scott towards the end of the 19th century and made commercially by the Ever Ready Battery Company between 1900 and 1910.
The principle of operation is that when the pendulum is swinging through a large arc, the gathering pawl picks up a tooth of the escape wheel causing it to rotate.
When the arc of swing decreases, the pawl catches in a notch at the top of the tooth. This raises the pawl causing the contacts to close, energising an electromagnet which gives the pendulum a further impulse.
It works on two 1.5 volt dry cells.
17. Spherical Skeleton Clock
A spherical skeleton clock invented around 1800 by Henri Gratte, London and was sold in New York for $37,400.
A gilt pointer indicates the time on horizontal rotating roman hour and Arabic minute rings. The horizontal fixed ring is engraved with names of oceans and geographic locations around the world.
The clock runs for 8 days and strikes hours and half hours.
18. Wagon-Spring Striking Skeleton Clock
This is an American convention whereby a semi-elliptic spring, as used in wagons and many cars, was used to power the clock.
Such clocks were produced in the 1830-1860 era. The principle involved employed the use of a single laminated spring which was fixed at its centre and then tensioned by drawing up cords at each end which are attached to the winding barrels.
Some of the clocks had 8 or 30 days running duration.
Well-known American makers were Joseph Ives, John Burge and Irenus Atkins.
26. Murday-Reason Electric Clock
The balance wheel is impulsed by an electromagnet when the amplitude of swing decreases to 180 degrees using a Hipp toggle arrangement. This version follows a design by John Wilding and is powered by a 3-volt battery in the base.
34. Congreve Clock
The time-keeping device is a ½ inch diameter ball bearing running in a zig-zag track which is tilted each time the ball arrives at the end.
The tilting of the track controls the rate at which the ball runs and hence the time indicated on the clock's dial which display the hours, minutes and seconds of the time rate.
The inventor was Sir William Congreve in London in 1808.
36. The Franklin 3 Wheel Clock
This is a skeletonised version of the line of clocks designed by the well-known American philosopher and scientist Benjamin Franklin.
To simplify construction only 3 wheels are used. The great wheel which carries the driving pulley has 160 teeth, the intermediate wheel has 120 and the escape wheel, which has 40 teeth, indicated seconds on the top dial.
To the great wheel is attached the single hand from which both hours and minutes can be easily read.
The hand goes round once every 4 hours.
XX. Perpetuum Mobile Clock
The original of this clock was constructed by Jean and David Geiser in Neuchatel in 1815. It represents a classical perpetual motion machine where the weights turn so that when on the right they are further from the axis. The resulting greater moment is supposed to keep the wheel turning.