ALTHOUGH July 4th is commonly associated with the American Declaration of Independence, it is in fact the anniversary of a much more significant event: it was on this date that Alice's Adventures in Wonderland were first related to a small but enthralled audience in a rowing boat on the River Isis outside Oxford. The party was led by the Rev Charles Lutwidge Dodgson, later known better by his nom de plume of Lewis Carroll, and included his niece Alice Liddell and her two small sisters.
Now if one were to judge from the internal evidence of the book, one might assume that the Adventures had taken place much earlier in the year. Of the March Hare it is said: "Perhaps as this is May, it won't be raving mad - at least not so mad as it was in March". But Dodgson recorded the events of the day in his diary, saying that they rowed from Oxford to Godstow and back, enjoying a warm sunny afternoon on the river, and his entry places the beginning of the Alice saga irrefutably on July 4th, 1862.
But was it warm and sunny? Carroll himself said it was and Alice reminisced years later about a "blazing summer afternoon with the heat haze shimmering over the meadows". But bearing in mind Humpty Dumpty's dictum in a similar context that "When I use a word it means just what I chose it to mean - neither more nor less", some corroborative detail from an independent source is called for on this vital question.
Rainfall records for the Oxford area, taken on their own, do not appear at first to support the evidence of Alice and her mentor. They show that a good deal of rain fell in the 12 hours prior to 2 am on July 5th, which might lead one to conclude that the afternoon on the 4th must have been cool and rather wet and that the memories of those present on that famous day were playing them false.
Since conventional weather maps for the early 1860s do not exist, meteorologists researching the issue have had to rely on contemporary weather reports from British harbours published in the London Times, Using these as one might use modern weather observations, it is possible to reconstruct weather maps for the period in question. Such an analysis shows that an active front had passed the Oxford area in the early morning of July 4th, and another moved - in from the west late that evening - to give the rain already noted in the records. In between, however, on the afternoon of the July 4th, a weak ridge of high pressure would, have allowed for fine conditions, and a vindication of the evidence provided by the main participants.