Annotations and comments

RSGII has posted 69 annotations/comments since 30 December 2015.


About Sunday 21 February 1663/64

RSGII  •  Link

Re preserving masts. The French buried the beams for their chateus in creeks for decades before using them.

About Sunday 24 January 1663/64

RSGII  •  Link

As a former US Navy navigator who has used a sextant, I can confirm how critical knowing the exact time is to knowing your position. If your chronometer is off by only a minute, your position could be off by about 15 miles. The great innovation of the chronometer is not that it kept exact time but that its rate of error was known so you could correct its reading to get the exact time. Of course, even then it is a bit of an art and if you get your position within 10 miles of where you actually are you are doing well.

About Saturday 16 January 1663/64

RSGII  •  Link

When studying engineering in the days before computers, we all used slide rules to do the calculations. Since the longer the rule, the greater the accuracy, a spiral rule which wrapped a longer scale many times in a spiral out from the center could give one slightly more accurate results and was also easier to carry. The linear rule had more scales and could be used for different calculations. I used both.

About Thursday 31 December 1663

RSGII  •  Link

Happy new year all. Sams 800 £ in 1663 when compared to the average wage then would require about 1.5 million pounds today compared to todays average wage. This is a better measure of his weath than the cpi comparison. Not bad for a young guy. See the fascinating site for various ways of comparing wealth over time. Of course 700 £ is lent to Sandwich, who is a credit risk not known for his prudent financial management.

About Tuesday 25 August 1663

RSGII  •  Link

I again draw your attention to the website for a sophisticated discussion of this issue and calculators for making various comparisons. Given the enormous changes in income, the types of goods and services purchased and the enormous growth in national wealth, the answers depends on the question. For example, Pepys paid his cook about 5 lb a year. Today a cook is said to earn about 25,000 lb a year, so the multiplier on this simple comparison would be 5000 not 100. Services are of course different than goods. Cheers

About Saturday 22 August 1663

RSGII  •  Link

Tomatoes, or certain varieties of tomatoes can be poison to certain people. About 50 years ago I visited a Rockefeller Foundation research station in India. One of their projects was to breed out the attribute of a local tomato that was fatal to a portion of the local population.

About Monday 12 January 1662/63

RSGII  •  Link

Sandwich's 8,000 pounds income would be equivalent to about 1 million pounds today using CPI or GNP deflator. To have the same ratio of income to the average wage, you would need to have an income of about 15 million today. See

About Monday 29 December 1662

RSGII  •  Link

Sam’s wealth of £630. Over the years there have been attempts to convert Sams wealth to modern terms using the CPI or GNP net deflator, most recently on 12/27/1662. While the results are not wrong, they are misleading, because they do not reflect the huge increase in wealth over the last 350 years.
There is a marvelous web site with the tools to correct this:, which describes the seven possible ways of measuring value over time and suggests which might be most appropriate for various purposes, e.g. the CPI o GNP deflator to understand the cost of coal in 1662. Plugging Sams £630 in gives about £80k using the CPI/GNP deflator methods, which is consistent with previous efforts. However this only tells us how much it would take to buy the basket of goods, food, heat, transport, labor that Sam bought. And these items are a much smaller share of our incomes today. If we compare Sam’s pot of gold to the average wage, or the GNP per capita, better measures of his relative wealth, you would need between £1.3 and 3.0 million today to have the same level of relative economic position he had with his £630 in 1662.
And the reason all of those tradesmen and “citizens” were happy to see him—his economic clout, his share of Britain’s 1662 GNP was the equivalent of someone with £20.6m today, a real city man or Silicon Valley type driving his 1662 Tesla!