136 YEAR-BOOK OF FACTS. 



ments and signals placed at their- extreme stations, in charge of and 

 used by their officials, only the necessary materials and instructions 

 will he required, all of which are ready or in progress. By vigilance 

 at the central station, and by taking great care to avoid signalling 

 too frequently, much may be done towards diminishing the losses of 

 life on our increasingly crowded coasts." 



OPEN «EA OF THE ARCTIC REGIONS. 



Mr. W. W. YVheildon, of Charleston, in a paper read to the 

 American Association, considers that the arguments in favour of the 

 Open Sea at the Pole being caused by the action of the Gulf- stream, 

 are inadequate; and that while the influence of the Gulf-stream has 

 been exaggerated, that of the air has been overlooked. He concludes 

 that the open sea is due largely, if not entirely, to the currents of 

 air from the equatorial region, which move in the higher strata of 

 the earth's atmosphere, bearing heat and moisture with them. He 

 cites the well-known fact that in the high polar regions the winds 

 blowing from the north and north-east are wann. 



PENDULUM EXPERIMENTS. 



Professor Pierce has read to the British Association a paper 

 " On the Motion of a Pendulum in a Vertical Plane when the Point 

 of Suspension moves uniformly on a Circumference in the same 

 Plane." The author wrote down the mathematical formula which 

 gave the laws which govern such motions. He then exhibited beau- 

 tifully-executed diagrams on transparent cloth, which showed by 

 curves, some most regular and some most fantastic in their forms, 

 the behaviour of such a pendulum under various conditions, and at 

 several periods of its course. He pointed out cases in which these 

 curves exhibited all the symmetry and regularity of exact mathe- 

 matical forms ; and others, in which these forms were complicated and 

 irregular almost beyond conception. He showed that in some of 

 these cases the state of the pendulum was that of a stable equili- 

 brium, whilst in others the equilibrium was unstable, and the pen- 

 dulum went off into the most rapid motions. By another series of 

 curves, something like Contour lines, he showed how the succession 

 of these motions oould hi] 1"- tracked ; and he concluded by showing 

 how a similar method was applicable to tne tracing of matter through 



its several varieties of form. Inorganic matter being analogous to 

 the changes and varieties observed in the state of stable equilibrium, 

 while the various states of unstable equilibrium gave many of the 



surprising and irregular transitions observed in the \. 

 animal kingdom, or in organized matters. 



si i :>i 01 9 iii' i:.\i:tii. 



PBorosBOB Hknnkssy has read to the British Association a paper 



"On the Possibility of Studying the Earth's Internal structure from 



Phenomena observed at its Surface." Ibis the author showed to 



from the comparison of the level surface, usually called the 



earth's surface by astronomers and mathematicians, with the geolo- 



