the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
New Zealand’s First Tide Gauge-based Sea Level Measurements
Abstract. James Cook’s second voyage to the South Seas, undertaken to settle the question regarding the existence or otherwise of the Great Southern Continent (Terra Australis Incognita), involved two vessels, the Resolution and Adventure. The Board of Longitude appointed two astronomers from the Royal Observatory, Greenwich, to the voyage, William Bayly and William Wales, one to each vessel. They were instructed, in addition to their astronomical duties, to observe the height and time of the tides. To this end, Bayly and Wales fabricated tide gauges and conducted timed measurements of sea level during their stopovers at Dusky Sound and Queen Charlotte Sound in 1773. This paper reviews those tidal observations, the first of their kind in New Zealand, using modern understanding of the tide, assuming that no significant change to the tidal regime at each location has taken place during the intervening period. When compared to the predicted (hindcast) astronomical tide, the majority (80 %) of the observed ranges and times agreed within 20 cm and 30 min respectively. Whilst their observations have little scientific value today (other than indicating the quality attainable in the late-18th century), Bayly and Wales can not only rightfully lay claim to making New Zealand’s first tide gauge measurements but also, as far as it possible to ascertain, be justifiably proud of the quality of their endeavours.
Glen Hamilton Rowe
Status: open (until 05 Apr 2023)
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RC1: 'Comment on hgss-2022-16', Wilko Graf von Hardenberg, 03 Mar 2023
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Thank you for this interesting paper. While I appreciate the way it handles the topic I think some more signposting would help the reader to have a clearer idea of which parts to prioritize. In particular, the source quotations need more context. Tell us why they are important and what we should take from them. Their English is not always easy to follow. Do not let the reader alone with it.
Please see the PDF for a few comments on specific points.
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RC2: 'Comment on hgss-2022-16', Christopher Jones, 12 Mar 2023
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A very interesting read, and clearly thoroughly researched. Thank you for the opportunity to review the manuscript. Just some minor comments:
Line 7: Would a brief explanantion of the Board of Longitude, its importance at the time etc., be of use to the reader?
Line 35: I think a brief explanantion of the phenomena "full & change of the Moon" would be beneficial.
Is it "Queen Charlotte Sound" (Line 10) or "Queen Charlotte’s Sound" (Line 40) [I think it is the former]?- this difference appears throughout the text.
Line 47: Should the latin term "prima facie" be in italics?
Line 188 "The predicted tide curve, based on modern data, is shown in blue". Would a little more detail on this modern-day analysis (timeseries analysies, no of harmnonic constituents, residual statistics etc), be of benefit to the reader?
General comment: Wales's "Tube" is essentially a 'stilling-well'. It could be worth making this comment somewhere in the text.
In the conclusions:
"These comparisons assume, firstly, that the tides have not changed materially during the intervening period..."...Might it be worth considering some sort of simple assessment of the bathymetry / geomorphology of the two locations over the years (i.e. between the dates of these historic observations to the dates of the modern-day records). This would then confirm that no significant 'natural' change has occurred adding to the validity of this statement.Line 424 "nonastronomical"? Would "non-astronomical" read better?
Line 431 "Whilst the sea level observations made by Bayly and Wales are of little scientific value today (but would have provided valuable information for mariners, in the absence of further observations meanwhile, until the mid-20th century), now they are historically significant as the first measurements by tide gauge in New Zealand."
Suggest rewording the last sentence to ".....their historical significance as the first measurements by tide gauge in new Zealand is undisputable."Citation: https://doi.org/10.5194/hgss-2022-16-RC2 -
RC3: 'Comment on hgss-2022-16', Philip Woodworth, 21 Mar 2023
reply
21/3/2023
Comments on "New Zealand’s first tide gauge-based sea level measurements" by Glen H. Rowe (HGSS)
I saw a draft of this paper a couple of months ago, so I have only a small number of extra comments here. Many of my comments are trivial wording things. The paper reads well and it refers to an intriguing aspect of Cook's scientific work in New Zealand.
8 - I would reverse the names of Wales and Bayly so as to have 'respectively' before ', one to each vessel'. Unless there is some reason to have Bayly first. That would then be consistent with the order of the ship names on line 6 and the location names on line 10. (I do understand though that the pair are usually referred to as Bayly first.)
23 - comma after journal
51 - I would end the sentence after 'commerce'. Then have:
This paper details the tide observations made by Bayly and Wales during their stopovers in New Zealand, and examines ...
57 - farmer's
58 - I would call him Nevil Maskelyne rather than Dr. I am not sure he was formally a Dr. anyway, usually he is referred to as Rev.
69 - give Mary's surname
74 - it is amazing this was painted a century later
97 - some readers are going to struggle with mean and apparent times so I would add here something like:
(Apparent or 'sun-dial' time can differ from local mean time by aproximately a quarter of an hour due to the 'equation of time', Hughes et al. 1989).
Hughes, D. W., Yallop, B. D., and Hohenkerk, C. Y.: The equation of time, Mon. Not. R. Astron. Soc., 238, 1529–1535,
https://doi.org/10.1093/mnras/238.4.1529, 1989.98 - and were twice
116 - The hand-written
130 - comma before 'was used'
139 - 'which begins at noon on the civil day'. I think you should mention here therefore that in the astronomical day (and the naval day) PM comes before AM. Also you should give a reference to where it is said that Bayly and Wales used the astronomical day in their records.
148-152 - this little section looks superficial. Could you not merge the two sentences into the following sections?
151 - .. predicted tides in an absolute way. Therefore, water ... limited to comparisons of sets of heights with offsets between them.
Or something like that, I have a problem with the way figures 5 etc. are plotted. You must have aligned the measurements and the predictions so they have the same average value? Otherwise I can't see how you can plot them both together. Then, what is the datum of the y-axis? I
suspect it is the chart datum of the predictions. This needs a slightly fuller explanation.
167 - The 1773 ... could then ..(You use 'Now' several times)
170 - comma before 'it was'
180 - .. Wales, and a comparison of their ...
190 - Gray (2020) is not in the references
191 - at noon of the corresponding civil day..
192 - Again, this needs a fuller explanation of what the heights are. Whether as shown in the original records or adjusted.
221 - and also a few in between
241 - when the largest spring tides
256 - this section is a quotation and should be indented
275 - drop 'rate of'. The 30 and 10 mm are heights and not rates
315 - maybe the 3 hours was just a throw-away remark. They were professional astronomers and their lunar transit times would have been reliable.
343, 349 - this is not the equilibrium tide involved here as such, it is just because of the length of the lunar day
345 - 29 to 119 min because of the role of tidal constituents other than the predominant lunar semidiurnal tide (M2), so that
367 - offset. They ..
414 - drop 'rate of'
417 - drop 'Regarding tidal ranges'
424 - insights into any tidal changes
The Haigh et al. paper discusses astronomical and non-astronomical tidal changes
429 - of tide heights presented
445 - heights and for the adjusted measured ones (presumably?)
Table A1, line 1 - 22:17 minus 22:21 should be -00:04 and not -00:17? I just spotted this by chance and I haven't looked at others
Table B1 - are these constants in timezonee 1200 or adjusted ones? Please make it clear. Give the timezone. Phase should be phase lag.
Citation: https://doi.org/10.5194/hgss-2022-16-RC3
Glen Hamilton Rowe
Glen Hamilton Rowe
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