The weather this week in 1673 was about the same as the weather in 2013 – terrible. Hooke reported cold, rain, frost, and snow during the week. The worst day was 3 April:

‘a continual snow from 6 in y^e morn till late at night when y^e wind rose stormy in y^e north. Th[ermometer] all day 2. The like day not knowne for cold & snow.‘

Unfortunately we can’t calibrate Hooke’s thermometer readings so I can’t tell you what ‘2’ meant, but it must have been pretty cold because that’s about the lowest reading Hooke ever recorded. Prompted by this entry, @roos_annamarie asked me whether there had been a frost fair on the Thames this year, but I can’t find any evidence that the Thames had frozen over so I think not – this was just a late cold snap. Europe was experiencing a ‘little ice age’ during this period and winters were cold. Occasionally reports came in to the Royal Society about the effects of severe frosts, particularly on trees (as in this letter about the effects of a strange frost in Somersetshire 1672). Sometimes the extreme weather could be put to good scientific use though. In February 1663 the Fellows ordered their assistant to freeze some cats’ eyes for the next meeting, ‘if the frost should hold’ (they wanted to know whether it would be easier to investigate the structure of the eye if it was frozen).

Perhaps because of the cold, Hooke spent more time at home this week than he usually did. On Sunday 30th he was (very unusually) ‘home till 5pm’; the following day, again, he was ‘at home till 4pm’, and then on Tuesday 1st April he was ‘at home till 3’. Unfortunately the diary doesn’t tell us what Hooke was doing at home – perhaps catching up on his reading. On Sunday 30th he recorded a note to himself: ‘M[emorandum] to write to Brother about shells’. His brother still lived on the Isle of Wight, where Hooke had grown up, and it’s possible that he was thinking here about the fossil shells that were (and are) found in the sea-cliffs on the island. Hooke had already written about fossils in Micrographia, where he suggested that they did not grow within the earth (as some of his contemporaries believed), but were the remains of shell-fish ‘fill’d with some kind of Mudd or Clay, or petrifying Water’ which had hardened into the shapes of the shells.

Hooke reported ‘a thin meeting’ of the Royal Society at Arundel House on Wednesday 2nd April – perhaps the bad weather had kept people away. It sounds like it must have been quite a fun afternoon though. Hooke presented the latest in his series of experiments on ‘penetration’, with surprising results (as described in the minutes of the meeting):

‘The Curator made an Experiment with mixing Oyle of Tartar and Aquafortis together, to see how they would incorporate, and how much lesse space they would take up when thus incorporated together, than both apart. This Mixture caused a great ebullition, which lasted all the while that the Society sate; but it ran over several times, and therefor the Curator was desired to make it again.’

Awesome! The chance of an explosion (or at the very least a ‘great ebullition’) was as attractive to early-modern chemists as it is to their colleagues in the present day, and the fact that the mixture had escaped from its beaker gave a good excuse to try the procedure again. ‘Oyle of Tartar’ was apparently a saturated solution of potassium carbonate (K2CO3), and aquafortis was nitric acid (HNO3). Don’t try this at home.

Hooke spent much of the rest of the week on his City work, doing surveys and writing reports. He was in better health this week and didn’t complain (much) about being unable to sleep. He tells us on 3rd April that he ‘drank scurvy grasse ale as I had done for a fortnight before.’ Scurvy grass (Cochlearia, or Spoonwort) has a high vitamin-C content and was much used as a cure for scurvy in the 18th century. I’m not sure how effective it would have been in ale, but probably better for him than some of the other remedies he took!

That’s all this week – but tune in next week for more chemistry, astronomical observations, and more Restoration herbal remedies.

And if you’re interested, you can read Hooke’s thoughts on fossil-formation in this section of Micrographia.