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Proceedings oj the Royal Society 
mum vapour tension of the day occurs about the time when the 
breeze from the lake falls to a calm, and before the land breeze 
springs up. 
A cursory examination of the curves suffices to show that there 
is a close connection between their critical phases and the corre- 
sponding phases of atmospheric pressure and temperature; and the 
idea is suggested that in this great contribution of Plantamour’s to 
the meteorology of Geneva, we are put in possession of data of the 
utmost importance as regards the relations of the vapour of the 
atmosphere and its movements to changes of atmospheric pressure 
in a way such as could be done by the observations of few observa- 
tories. 
5. On Knots. By Professor Tait. 
(Abstract.) 
At the last meeting of the Society I stated that I had just pro- 
cured a remarkable essay by Listing, part of which bears on the 
subject of knots, and that I had found in it an example of a change 
of form not producible by the modes of deformation I had employed. 
It had for some time struck me as very singular that, thoug I 
could easily prove that (when nugatory intersections are removed) 
a knot in which the crossings are alternately over and under is not 
farther reducible, I could not prove all its possible deformations to 
be producible by inversions or projections of the kinds specified in 
my paper; but, as soon as I recognised the existence of amphi- 
cheiral forms, I saw that it was probable that they would furnish a 
key to my difficulty. I immediately set to work to classify the 
simpler of such forms; and while I was thus engaged I got the 
Gottinger Studien for 1847, in which is Listing’s paper, with the 
title Vorstudien zur Topologie. 
By this title Listing means qualitative as distinguished from 
quantitative space-relations. He commences with a study of inver- 
sion ( UmJcehrung ) and perversion (Verkehrung'), — the first being the 
effect of a rotation through two right angles about any axis, the 
second the result of reflexion in a plane mirror. 
He next treats of screwing of all kinds, including twisting and 
plaiting. 
