# So what was Harrison's big breakthrough wrt the chronometer? **URL:** \ **Category:** Factual Questions\ **Created:** [August 21, 2003, 1:26pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654 "2003-08-21T13:26:59Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![The\_Stafford\_Cripps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_stafford_cripps/32/7167_2.png) [@The\_Stafford\_Cripps](https://boards.straightdope.com/u/The_Stafford_Cripps)\ **Post date:** [August 21, 2003, 1:26pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/1 "2003-08-21T13:26:59Z")
Since I’m asking another GQ on longitude I thought I’d try find out something that’s been bothering me for a couple of years since I read Sobel’s “Longitude”. She writes very interestingly about the 18th century quest to find an accurate way of telling the time at sea, which was necessary in order to determine the ship’s east - west position. However she goes into disappointingly little detail on how John Harrison finally solved the problem when he made “H4”, the chronometer which is really a very accurate watch. Until then he had been labouring with clock technology, as watches were regarded as too innaccurate. Sobel does not explain how Harrison managed to suddenly and so dramatically improve watch technology, other than mentioning something about jewels used to combat friction. I’m guessing that the problem was something to do with the watchspring, which is used instead of a pendulum to regulate the seconds, but what did Harrison actually do to improve the watchspring, or whatever? ---
**Author:** ![rabbit](https://avatars.discourse-cdn.com/v4/letter/r/919ad9/32.png) [@rabbit](https://boards.straightdope.com/u/rabbit)\ **Post date:** [August 21, 2003, 2:20pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/2 "2003-08-21T14:20:55Z")
It wasn’t “suddenly”. In the documentary I saw on him it apparently took him over 40 years of experimentation to get the design and several false starts. Near as I remember the innovation was making a timepiece whose movement was unaffected by motion and changes in temperatures. You can read a little more here. [http://www.nmm.ac.uk/site/request/setTemplate:singlecontent/contentTypeA/conWebDoc/contentId/355/viewPage/1](http://www.nmm.ac.uk/site/request/setTemplate:singlecontent/contentTypeA/conWebDoc/contentId/355/viewPage/1) ---
**Author:** ![godzillatemple](https://avatars.discourse-cdn.com/v4/letter/g/49beb7/32.png) [@godzillatemple](https://boards.straightdope.com/u/godzillatemple)\ **Post date:** [August 21, 2003, 2:28pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/3 "2003-08-21T14:28:05Z")
From [this site](http://easyweb.easynet.co.uk/~robodyne/inventors-world/iwharris.htm): > [@](#): > > no one in the 1750’s thought of the pocket watch as a serious timekeeper. Harrison discovered with his new watch, however, that if made with certain vital improvements, it had the potential to be an excellent timekeeper. He found that timepieces with small, high frequency oscillators (such as the watch balance), if made to the correct proportions, are much more stable timekeepers when they are carried about than the earlier ‘portable clocks’. This apparently simple discovery is one of Harrison’s great achievements. and > [@](#): > > Technically, however, it was different from an ordinary watch in a number of significant ways. Apart from being very finely constructed, its balance was much larger, although still relatively light, and of higher frequency: it oscillated five times a second. This means the balance had a great deal more energy stored in it when running, which rendered it much less vulnerable to physical disturbance. Temperature change was compensated for by using the bimetallic strip, a smaller version of H3’s device. It also contained a miniature remontoir, rewinding eight times a minute to ensure constant power. A type of verge escapement (the sort used in common watches) was fitted, of a modified form, which ensured that the balance was isochronous. Although Harrison was unable to miniaturise the anti-friction devices and H4 required oil on all its bearing surfaces, jewelled bearings were fitted in many places to reduce friction to a minimum. The use of jewelled bearings was not Harrison’s invention (their use had been known since their introduction by Nicholas Facio (1664-1753) and the Debaufre brothers Peter (1646-1722) and Jacob, in London in 1704), but such extensive use was quite revolutionary. In common with the other three timekeepers, the watch also has maintaining power, a device to ensure that the mechanism keeps going while it is being wound up. In Harrison’s version, this is automatic and does not need to be brought into action manually. Of the highest quality throughout, the upper plates of the movement are beautifully engraved. Hope this helps! Barry ---
**Author:** ![The\_Stafford\_Cripps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_stafford_cripps/32/7167_2.png) [@The\_Stafford\_Cripps](https://boards.straightdope.com/u/The_Stafford_Cripps)\ **Post date:** [August 21, 2003, 2:32pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/4 "2003-08-21T14:32:33Z")
It was actually more sudden than you make out. Much of the 40 years of experiment was with clocks; his breakthrough came when he decided to go for a completely different type of timepiece. You only need to look at how different H1, H2 and H3 are from H4 to realise this. At first glance that website also does not appear to answer the point of my question; what did Harrison do to so dramatically improve watch technology? ---
**Author:** ![The\_Stafford\_Cripps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_stafford_cripps/32/7167_2.png) [@The\_Stafford\_Cripps](https://boards.straightdope.com/u/The_Stafford_Cripps)\ **Post date:** [August 21, 2003, 2:34pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/5 "2003-08-21T14:34:42Z")
Thanks, **godzillatemple** , that’s more what I’m looking for. ---
**Author:** ![godzillatemple](https://avatars.discourse-cdn.com/v4/letter/g/49beb7/32.png) [@godzillatemple](https://boards.straightdope.com/u/godzillatemple)\ **Post date:** [August 21, 2003, 2:39pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/6 "2003-08-21T14:39:25Z")
My pleasure. The author of the information I quoted is none other than Jonathan Betts, the Curator of Horology at the National Maritime Museum, Greenwich. Let me know, BTW, if you need assistance with any of the terminology in that article. Barry * * * Come visit my [Pocket Watch Collection](http://barrygoldberg.net/watches.htm)! ---
**Author:** ![NurseCarmen](https://avatars.discourse-cdn.com/v4/letter/n/5daacb/32.png) [@NurseCarmen](https://boards.straightdope.com/u/NurseCarmen)\ **Post date:** [August 21, 2003, 2:55pm UTC](https://boards.straightdope.com/t/so-what-was-harrisons-big-breakthrough-wrt-the-chronometer/196654/7 "2003-08-21T14:55:35Z")
IIRC, he used metals. Wood was in common use for parts back then (for bearings even!), making them much larger, but he skipped wood and stuck to metals. This also allowed him to use oil instead of the “Frictionless wheels” Which, over the space of an atlantic crossing, actually produced enough friction to throw even the chronometers made by the finest craftsmen end up off by not only minutes, but hours, and minutes=miles. IIRC, he was anal enough to produce gears with a higher number of teeth, with ended up making everything a bit more exact. I think that it really was just a bunch of little things that he did that made it such a breakthrough. Some of the best inventors don’t come up with new things, they just take existing things and combine them in ways no-one has ever thought of.