218 



V. Prof. A. exhibited also a Diagram of Sundry Curves illustrative 

 of the Equation of Time. 



The first was a curve of contrary flexure, the abscissas of which 

 were proportionate to time, while the ordinates represented the 

 amount of equation due to the obliquity of the ecliptic. This curve 

 intersected the axis of abscissas at the points representing the instants 

 of the equinoxes and solstices. The second curve was similarly con- 

 structed, and had the same axis of abscissas, but its ordinates repre- 

 sented the amount of equation due to the elliptical form of the earth's 

 orbit, and, consequently, intersected the common a.^is of abscissas at 

 the points representing the instants of the earth's arrival at the aphe- 

 lion and perihelion. The third curve was formed by referring to a 

 new, and in all respects similar axis of abscissas, the algebraic sum 

 of the coexisting ordinates of the two former curves. It intersected 

 the new axis of abscissas at the points representing the instants at 

 which the actual equation of time is zero. 



By supposing the second curve to change its position by a transfer 

 along the common axis of abscissas, while the first remained nearly 

 fixed, it was observed that the changes in the equation of time, for a 

 period either past or future, might be readily exhibited. 



Mr. Justice made the following communication to the So- 

 ciety: — 



Whilst trying some experiments with a five bar horse shoe mag- 

 net, whose force was equal to raising five pounds in weight, I had 

 ■occasion to place a needle afloat on the surface of water contained in 

 a glass tumbler. The needle accidentally sinking during the experi- 

 ment, induced me to apply the magnet outside of the tumbler, to raise 

 it again; this was easily done, the needle following up the side of the 

 tumbler the poles of the magnet, which were kept on a plane, so as 

 to admit of it being raised in a horizontal position. To my great 

 surprise, when the needle was thus raised to the surface of the water, 

 and the magnet withdrawn, it again floated as though it had not been 

 wetted ; the experiment was frequently repeated with like results, and 

 on close observation the particles of water seemed to be unusually 

 agitated. 



The Treasurer, Mr. Ord, presented his account, which, in 

 accordance with the regulations of the Society, was referred to 

 the Committee on Finance. 



