Curiosities of Science. 203 



to follow out the great phenomena of creation in their perfect 

 development, interrupted the observation in VanDiemen's Land, 

 where, in consequence of the difference of the longitude, the 

 magnetic storm fell on Sunday." 



It is but justice to add. that to the direct instrumentality of the Bri- 

 tish Association we are indebted for this system of observation, which 

 would not have been possible without some such machinery for concerted 

 action. It being known that the magnetic needle is subject to oscilla- 

 tions, the nature, the periods, and the laws of which were unascertained, 

 under the direction of a committee of the Association magnetic observa- 

 tories were established in various places for investigating these strange 

 disturbances. As might have been anticipated, regularly recurring per- 

 turbations were noted, depending on the hour of the day and the season 

 of the year. Magnetic storms were observed to sweep simultaneously over 

 the whole face of the earth, and these too have now been ascertained to 

 follow certain periodic laws. 



But the most startling result of the combined magnetic observations 

 is the discovery of marked perturbations recurring at intervals of ten 

 years ; a period which seemed to have no analogy to any thing in the 

 universe, but which M. Schwabe has found to correspond with the varia- 

 tion of the spots on the sun, both attaining their maximum and mini- 

 mum developments at the same time. Here, for the present, the dis- 

 covery stops ; but that which is now an unexplained coincidence may 

 hereafter supply the key to the nature and source of Terrestrial Magne- 

 tism : or, as Dr. Lloyd observes, this system of magnetic observation 

 has gone beyond our globe, and opened a new range for inquiry, by 

 showing us that this wondrous agent has power in other parts of the 

 solar system. 



FAMILIAR GALVANIC EFFECTS. 



By means of the galvanic agency a variety of surprising 

 effects have heen produced. Gunpowder, cotton, and other in- 

 flammable substances have been set on fire ; charcoal has been 

 made to burn with a brilliant white flame ; water has been de- 

 composed into its elementary parts ; metals have been melted 

 and set on fire ; fragments of diamond, charcoal, and plumbago 

 have been dispersed as if evaporated ; platina, the hardest and 

 the heaviest of the metals, has been melted as readily as wax 

 in the flame of a candle ; the sapphire, quartz, magnesia, lime, 

 and the firmest compounds in nature, have been fused. Its 

 effects on the animal system are no less surprising. 



The agency of galvanism explains why porter has a different 

 and more pleasant taste when drunk out of a pewter-pot than 

 out of glass or earthenware ; why works of metal which are 

 soldered together soon tarnish in the place where the metals are 

 joined ; and why the copper sheathing of ships, when fastened 

 with iron nails, is soon corroded about the place of contact. In 

 all these cases a galvanic circle is formed which produces the 

 effects. 



THE SIAMESE TWINS GALVANISED. 



It will be recollected that the Siamese twins, brought to 



