Dial clocks are so called because they are little more than a dial in a circular wooden case for hanging on a wall.
The majority have twelve inch dials set in slightly larger hardwood surrounds (usually mahogany or walnut) but they can be as large as 24 inches across and more, where they were designed for public use. But they can also be as small as eight inches across and those smaller ones often fetch higher prices because they better suit a smaller modern house.
There are broadly three types. American dial clocks made by Ansonia, Seth Thomas, Gilbert, Waterbury, Ingraham etc are comparatively rare but that does not make them highly valuable. Ansonia made more drop dial clocks that simple dial clocks - the drop dial gave scope for a longer pendulum which usually means more accuracy and reliability, so that might explain it. I suspect, however, that their factory produced suitable movements already and that they did not see the demand to justify changing it. Some have a date ring and a long red calendar hand, usually housed in an octagonal frame. And all of them have open springs (no barrels). You'll see quite a few Ansonias with a strike train as well but you should listen to them before buying as many sound like a bag of spanners when the wheels start turning!
Most of the rest of the dial clocks you'll see are English, but there are three distinct types.
First there are recent electric dial clocks, run by an electric motor directly from the mains supply, which are easy to spot as soon as you turn then over. The power is supplied by a synchronous motor which relies on the mains frequency so they are very accurate and yet very inexpensive though still very collectible in some quarters, especially if the frame is in bakelite (an early form of plastic). Watch out, though, as some have "slave" movements and require a "Master" to drive them. These were frequently used in schools, post offices (remember those???) and public buildings like police stations, libraries and the Town Hall in the nineteen fifties and sixties.
Before that were the cheaper mechanical dial clocks with pendulum, often 8-day but sometimes 30 hour, and often still in a mahogany (or oak) case but sometimes with a softwood case like pine. These are comparatively inexpensive and have a simple spring-driven movement by Enfield or Smiths where the spring is contained inside a barrel. The digits might well be Arabic rather than Roman. But those with Roman numerals in a mahogany case look very like the more valuable ones described below and there is a massive difference in value so be careful to check before you buy.
Finally, there are the 8-day fusée dial clocks. These were used on the railways and other public places where accuracy was important . The fusée is a conical shaped brass wheel linked to the mainspring barrel by a line of some sort, made from chain, natural gut or steel cable. It is designed to balance out the tendency for a mainspring to retain less and less power as it gradually unwinds and releases its power. If you're technically minded, you can see some illustrations and find out more about this on my FUSEES page.
The dials and hands were rarely decorated as they were functional timepieces rather than objects to admire. For the same reason, they rarely struck the hours. Early fusée dial clocks are particularly collectible, immediately distinguishable by their slimmer hands and brass bezels, and by their domed dials and convex glass. Under the dial, the wheels of the brass movement are finely crossed out, and the plates are always riveted and pinned together, not screwed front and back.
One of the most prolific makers of dial clocks were Gillett & Bland of Croydon (later Gillett & Johnston) but take special care because there are a great many fake dial clocks from India bearing that name on the dial, often mis-spelled! Other names to watch out for are Atkinson, Allen, Jones, and SIR Walker. Some even have LNER on them to suggest they are former railway clocks but the curious thing is that more often than not the brass plates (that you can only view if you remove the back box) are stamped 'London' and/or '6472'. I have a separate page devoted to these fake versions so check out FAKE DIAL CLOCKS if you're thinking of buying a dial clock or are suspicious about one you already have.
The best book on the dial clock is the one by Ronald Rose, which gives a lot of history and some very good tips on dating. Ian Lyman has also written a good book recently with emphasis on Railway dial clocks. Neither is cheap but they make good reading and excellent reference material to dip into when you need to.
Another interesting and very inexpensive book is The Chain Makers by Allen White (recently republished in paperback) which explains how children of seven and eight were employed in Hampshire and Dorset (UK) to make the tiny fusée chains for watches. It's more history than horological.
My charges for servicing and repairing dial clock movements vary from £125 for a simple pendulum timepiece to £175 for a striker or a fusée timepiece. For that I will strip the movement to clean it piece by piece, check for wear and the correct engagement of parts, rebush up to two pivot holes if needed, oil it and set it in beat. I can replace broken glass, bezels, hands and even repaint dials but these would be at additional cost as would any restoration work on the case.
All paid for work's guaranteed for a year.