READERS of this column anxious to find an explanation for the recent spell of bitter weather cannot do better than seek out a little pamphlet by one Heinrich Wilhelm Dove entitled Uber die Ruckfalle der Kalte in Mai - Concerning the Reversion to Cold Weather in May".
It was published by the Academy of Sciences in Berlin in 1856, and contains indispensable information about this phenomenon. Those who wish to dig even deeper may also consult Grosswetter- singularitaen im Jahrlichen Witterungsverlauf Mittele-uropas by Messrs Flohn and Hess but that is another story; let us concentrate on Dove, pronounced "Doh - fey", for the moment.
Herr Dove's little essay is an analysis of what, over the centuries, was believed to be a regular phenomenon a cold spell in the second week in May. Alexander Buchan noticed it, as we saw yesterday, when he marked out certain periods of the year as being unseasonably cold or warm: the period from May 9th to 14th was one of his "cold spells".
But the feeling goes back even further. This in mainland Europe is the period of the "Ice Men", or the "Frost Saints" as they are sometimes known. These are the four saints Marnertus, Pancras, Servatius and Boniface - whose feastdays fall on May 11th, 12th, 13th and 14th respectively, a four-day period during which a sharp and injurious frost was thought to be inevitable.
But is it true? Dove tells us that in central Europe between 1766 and 1845, frosty weather did in fact occur more often than one might expect on the "Ice Men" dates. And there were explanations for it too!
It is well known that the earth's orbit is such that at certain times each year the planet passes through predictable shoals of meteors, which often provide a brilliant show of shooting stars. One such shower of meteors comes in August; another is at its peak in mid-November; and there is a third meteor shower which occurs regularly between May 10th and 13th.
Nineteenth-century meteorologists blamed this last for the drop in temperature in May.
Unfortunately, the regular pattern went astray from the 18505 onwards, and although meteor showers are still a regular feature of our astronomical year, there is no statistical evidence to link them to any icy spell around this time of year. We in Ireland, in fact, tend to relate such chilliness to the annual re-appearance of the cuckoo: a cold snap in the last few days of April or the early days of May was known to our forefathers as Scairbhin na gCuac.