Victorian Tide time

[JIM_TEAL]

Reading"Sailing Tours" by FrankCowper I am intrigued and puzzled by his descriptions of tide times.
St Ives: It is highwater full and change at 4hr 44min localtime of 5hr 6min Greenwich time.
What does this mean. Does Local Time refer to the fact that
time varied across the country pre speaking clocks etc. I understood that the Railways had brought Standard time across the British Isles well before 1892 when the book was written.
What does the time difference relate to? Tide time at Dover, London or???
Anybody know /forums/images/graemlins/confused.gif

 

[Norman_E]

The branch railway line to St. Ives was only completed in 1877 so it is possible that "local time" was still in use a few years later, but it seems unlikely that it survived to 1892. Perhaps the book was published in 1892 but based on visiting St. Ives some years before?

 

[Black Sheep]

That does sound like the right difference to be local time as opposed to GMT

St Ives rounghly 5.5 degrees west. 15 degrees is 1 hour time difference, 5.5/15 = 0.36667 hours, or exactly 22 minutes, which is what you have. So when it's 5:06pm in Greenwich, it's only 4:44pm in St Ives.

As for why it was being used in 1892, I'm not sure. Wikipedia says: Greenwich Mean Time was adopted across the island of Great Britain by the Railway Clearing House in 1847, and by almost all railway companies by the following year. It was gradually adopted for other purposes, but a legal case in 1858 held "local mean time" to be the official time. This changed in 1880, when GMT was legally adopted throughout the island of Great Britain.

So GMT had been official for over a decade. But maybe people still clung to their local standards.

 

[KenMcCulloch]

[ QUOTE ]
That does sound like the right difference to be local time as opposed to GMT

St Ives rounghly 5.5 degrees west. 15 degrees is 1 hour time difference, 5.5/15 = 0.36667 hours, or exactly 22 minutes, which is what you have. So when it's 5:06pm in Greenwich, it's only 4:44pm in St Ives.

As for why it was being used in 1892, I'm not sure. Wikipedia says: Greenwich Mean Time was adopted across the island of Great Britain by the Railway Clearing House in 1847, and by almost all railway companies by the following year. It was gradually adopted for other purposes, but a legal case in 1858 held "local mean time" to be the official time. This changed in 1880, when GMT was legally adopted throughout the island of Great Britain.

So GMT had been official for over a decade. But maybe people still clung to their local standards.

[/ QUOTE ]

I've always been curious about exactly how these traditional specifications of tidal data worked. It may be that local noon was used as a reference because that was (and had 'always' been available without a clock). It's also likely that seamen were still using practices in this regard that had developed over the preceding centuries notwithstanding the impact of the railways. If there's a maritime historian (amateur or professional) out there who can give a more informed response I'd be interested to hear it.

 

[Norman_E]

You raise an interesting possibility.
A yachtsman in 1892 would probably not have an expensive marine chronometer, but would probably have a pocket watch of reasonable accuracy over a day, but not over long periods. The yachtsman could himself observe sunrise and sunset timed by his watch and calculate noon as the mid point between them, and thus set his watch fairly accurately to local time. I do not know what tide tables were available then, but they may well have been written using locally observed time in some places.

 

[Searush]

Fantastic book "Sailing Tours". I love comparing his descriptions with current pilot guides.

Interesting discussion of "local times", it seems very likely to me that things changed much slower then than now. No telly or radio to give instant time checks!

OK; so the Railways needed a consistent national time to avoid accidents between trains from different companies, or to meet ferries. But no-one else would really care, so it is very likely that the change wouldn't spread very fast.

People don't like change - never have and never will!

 

[JIM_TEAL]

Thanks all, but what does the time /forums/images/graemlins/confused.gif refer to, Dover or somewhere else?
Jim J

 

[Norman_E]

Interesting webpage here explains some definitions of time and has a "local observed time" calculator.
Wikipedia has an easy to understand explanation of sidereal time.

 

[Searush]

[ QUOTE ]
Thanks all, but what does the time /forums/images/graemlins/confused.gif refer to, Dover or somewhere else?
Jim J

[/ QUOTE ]

Not quite sure what you are asking. He is quoting the time of HW Spring tides (Full & change) in local time (literally related to noon at that spot) and related to Greenwich noon (GMT).

As others have already stated, few would be able to afford chronometers or even quality watches in those days, but local noon could be checked from shadow movements so a basic watch could be set accurately enough for most purposes.

 

[KenMcCulloch]

[ QUOTE ]

St Ives: It is highwater full and change at 4hr 44min localtime of 5hr 6min Greenwich time.
What does this mean. Does Local Time refer to the fact that
time varied across the country pre speaking clocks etc. I understood that the Railways had brought Standard time across the British Isles well before 1892 when the book was written.
What does the time difference relate to? Tide time at Dover, London or???
Anybody know /forums/images/graemlins/confused.gif

[/ QUOTE ]
Well you have just forced me to do some research. These tide times are expresssed as a relationship to lunar meridian passage. Any mariner in Cowper's time would have an almanac aboard that would enable him to calculate the time the moon passed the meridian on a given day, and the times for HW on the days the moon was full and new (change) could thus be calculated. The times given are not times but differences so that HW on the days of full and new moons should be expected 5hrs 6mins after (I think it will be after) the time of lunar meridian passage using GMT. I am grateful to Paul Hughes for publishing reviews of some of the literature on the history of tide science at
http://www.airmynyorks.co.uk/bcart.htm
-and enabling me to expand my own knowledge. /forums/images/graemlins/confused.gif