Re: Inquiry - Part 2
Hi all, This link indicates when the telegraph was 1st perfected. 1837 Cook and Wheatstone in England. http://www.persee.fr/doc/flux_1154-2721_1993_num_9_11_939 Regards, Roderick Wall. - Reply message - From: "Frank King" <f...@cl.cam.ac.uk> To: "Steve Lelievre" <steve.lelievre.can...@gmail.com> Cc: "sundial@uni-koeln.de" <sundial@uni-koeln.de> Subject: Inquiry - Part 2 Date: Wed, Apr 26, 2017 10:46 PM Dear Steve, Part 2 of your enquiry asserted that... ...throughout the 19th century... the French railways system used heliochronometers installed at each station for daily calibration of station clocks? Again, this is a good story but I simply cannot see why this would be true... Just for a start, "throughout the 19th century" cannot be right. The railways were not introduced to France until the late 1820s. High-quality French chronometers had been around since the 1760s with Le Roy being the leading maker. The early railways could have distributed time using these, just as happened in England. The Paris Observatory was never far behind Greenwich in terms of tracking time and could have provided definitive railway time in France. In England, the first railway to adopt the electric telegraph was the Great Western Railway in 1839 and this provided another way of distributing time. Why would the French railways have used heliochronometers? That said, it is not hard to find references to this practice. For example, in "Sundials: History, Theory and Practice" by Rene R.J. Rohr. Take a look at: https://books.google.co.uk/books?isbn=0486151700 On page 16 we see he writes: ...this instrument [heliochronometer] was used into the twentieth century by some networks of the French railways for uniformity in the setting of the station clocks. I can just about believe that an eccentric station master might have set the station clock via a heliochronometer but train dispatchers and signalmen and others who actually implemented the timetable would have had company watches in their waistcoats. These were set by more reliable means. On page 17 you see a drawing of a "heliochronometer" which is just a simple semi-equatorial dial with no obvious means for longitude correction never mind EoT. This is not my idea of a heliochronometer. Please can someone find a contemporary account of a French stationmaster describing his use of a heliochronometer. Until I can read this in French, I shall deem the account to be yet another example of a much-repeated falsehood that has gained widespread acceptance. I should be delighted to be proved wrong on both matters! Frank Frank H. King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Inquiry - Part 2
Hi Frank and Steve, This link is interesting on early telegraph systems in France. http://www.bbc.com/news/magazine-22909590 Roderick Wall. - Reply message - From: "Frank King" <f...@cl.cam.ac.uk> To: "Steve Lelievre" <steve.lelievre.can...@gmail.com> Cc: "sundial@uni-koeln.de" <sundial@uni-koeln.de> Subject: Inquiry - Part 2 Date: Wed, Apr 26, 2017 10:46 PM Dear Steve, Part 2 of your enquiry asserted that... ...throughout the 19th century... the French railways system used heliochronometers installed at each station for daily calibration of station clocks? Again, this is a good story but I simply cannot see why this would be true... Just for a start, "throughout the 19th century" cannot be right. The railways were not introduced to France until the late 1820s. High-quality French chronometers had been around since the 1760s with Le Roy being the leading maker. The early railways could have distributed time using these, just as happened in England. The Paris Observatory was never far behind Greenwich in terms of tracking time and could have provided definitive railway time in France. In England, the first railway to adopt the electric telegraph was the Great Western Railway in 1839 and this provided another way of distributing time. Why would the French railways have used heliochronometers? That said, it is not hard to find references to this practice. For example, in "Sundials: History, Theory and Practice" by Rene R.J. Rohr. Take a look at: https://books.google.co.uk/books?isbn=0486151700 On page 16 we see he writes: ...this instrument [heliochronometer] was used into the twentieth century by some networks of the French railways for uniformity in the setting of the station clocks. I can just about believe that an eccentric station master might have set the station clock via a heliochronometer but train dispatchers and signalmen and others who actually implemented the timetable would have had company watches in their waistcoats. These were set by more reliable means. On page 17 you see a drawing of a "heliochronometer" which is just a simple semi-equatorial dial with no obvious means for longitude correction never mind EoT. This is not my idea of a heliochronometer. Please can someone find a contemporary account of a French stationmaster describing his use of a heliochronometer. Until I can read this in French, I shall deem the account to be yet another example of a much-repeated falsehood that has gained widespread acceptance. I should be delighted to be proved wrong on both matters! Frank Frank H. King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Inquiry - Part 2
Dear Steve, Part 2 of your enquiry asserted that... ...throughout the 19th century... the French railways system used heliochronometers installed at each station for daily calibration of station clocks? Again, this is a good story but I simply cannot see why this would be true... Just for a start, "throughout the 19th century" cannot be right. The railways were not introduced to France until the late 1820s. High-quality French chronometers had been around since the 1760s with Le Roy being the leading maker. The early railways could have distributed time using these, just as happened in England. The Paris Observatory was never far behind Greenwich in terms of tracking time and could have provided definitive railway time in France. In England, the first railway to adopt the electric telegraph was the Great Western Railway in 1839 and this provided another way of distributing time. Why would the French railways have used heliochronometers? That said, it is not hard to find references to this practice. For example, in "Sundials: History, Theory and Practice" by Rene R.J. Rohr. Take a look at: https://books.google.co.uk/books?isbn=0486151700 On page 16 we see he writes: ...this instrument [heliochronometer] was used into the twentieth century by some networks of the French railways for uniformity in the setting of the station clocks. I can just about believe that an eccentric station master might have set the station clock via a heliochronometer but train dispatchers and signalmen and others who actually implemented the timetable would have had company watches in their waistcoats. These were set by more reliable means. On page 17 you see a drawing of a "heliochronometer" which is just a simple semi-equatorial dial with no obvious means for longitude correction never mind EoT. This is not my idea of a heliochronometer. Please can someone find a contemporary account of a French stationmaster describing his use of a heliochronometer. Until I can read this in French, I shall deem the account to be yet another example of a much-repeated falsehood that has gained widespread acceptance. I should be delighted to be proved wrong on both matters! Frank Frank H. King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
