Mr. A.Day on the Rotation of the Pendulum, 19 



meter. A stronger electroscopic arrangement was obtained when 

 the tube contained mercury, or a liquid amalgam of zinc, and 

 was surrounded by peroxide of manganese or powdered charcoal 

 pressed firmly together. The condenser received from the mer- 

 cury or the amalgam negative, and from the peroxide of manga- 

 nese or the coal positive electricity. The current passed, there- 

 fore, from the amalgam through the glass to the peroxide, and 

 thence through the connecting wire, just as it would proceed had 

 water been used instead of glass. The charge was augmented 

 considerably by heating the apparatus, and it was found that 

 such an arrangement was capable of exhibiting phsenomena of 

 polarization similar to those already described. 



Piles can also be formed without difficulty in which the 

 liquid conductor is superseded by glass. Brass discs gilt, clean 

 discs of zinc and thin plates of glass, were placed one over the 

 other in the same order. To the first gilt disc, and also to the 

 last which covered the tenth plate of glass, platinum wires were 

 attached; the pile thiis formed was only 4 centimetres high. 

 The plates were so pressed together that they might be exposed 

 to the hot current of an Argand lamp. When time was permitted 

 to this little pile, the condenser at ordinary temperatures could 

 be charged to a tension of three or four lines divergence of the 

 gold-leaf electrometer. When the discs were heated, a few; 

 seconds' connexion with the condenser produced a divergence of 

 at least fourteen lines. Such a pile constructed in 1853, and 

 often used, did not in five months lose in the smallest degree its 

 primitive electroscopic force. 



III. On the Rotation of the Pendulum. By Alfred Day, Esq, 



To the Editors of the Philosophical Magazine and Journal. 



Westbury on Trym, near Bristol, 

 Gentlemen, May 23, 1854. 



HAVING been one of the parties who, in an early stage of 

 the inquiry, proposed a simple original solution of the 

 phsenomena of the rotation of the pendulum, which is now com- 

 monly adopted without acknowledgement, and which has been 

 again and again repeated both here and in America, I am de- 

 sirous of correcting some unsatisfactory representations which 

 still find their way into print in works of a respectable class. I 

 refer to the account given of the problem in a manual of the 

 physical sciences by Dr. Golding Bird and Mr. Brooke, where 

 the correct explanation is also given, being exactly the same as 

 my own, even to the form in which the trigonometrical relation 



C2 



