194 Miscellanies. 



this particular disposition of the metals which compose the elementary 

 electromotor. 



The surprising effect of Wollaston's miniature battery as well as 

 those of Children's great battery which were not proportioned to the 

 metallic surface of the battery are explained by these results. — Idem. 



9. Magnetic Experiments. — Mr. Kupffer in a letter to Sir D. 

 Brewster, announces that he has found, that the intensity of magnetic 

 forces, in steel bars, diminishes as much by the action of cold as by 

 that of heat. 



To obtain magnetic cylinders, of constant power, to measure the 

 intensity of the magnetism of the earth, he not only plunges them 

 many times into boiling water, but cools them as often to 20° or 25°, 

 below zero, of Reaumur. 



Mr. K. has proved by a direct method, the existence of a daily 

 variation in the dip of the magnetic needle, and in the intensity of 

 the earth's magnetism — the latter, by observing, each day, the extent 

 and duration of the oscillations of a needle of a large dip and suspended 

 upon the edge of a knife. 



He found that the dip was greater by some minutes at eleven A. M, 

 than at eleven P. M. and that the intensity of the earth's magnetism 

 is much greater at night than in the morning.; — Phil. Mag. March, 

 1832. 



10. Phenomenon presented by the breaking of a Prince Ruperfs 

 drop. — M. Bellani has observed that in breaking the tip of a Prince 

 Rupert's drop, under the water contained in a glass receiver, the lat- 

 ter is broken with an explosion, at the very moment and even when 

 the surface of the water is uncovered. He attributed this effect to 

 the rapidity with which the drop is broken and to the consequent ex- 

 pansion, so great that the water has not time to yield, but com- 

 municates, like a solid body, the motion to the sides of the receiver. 



This phenomenon is similar to that which occurs when a ball is 

 discharged from a pistol upon the surface of water — the ball is com- 

 pressed and flattened as it would be if fired against a solid body. — 

 Bib. Univ. Feb. 1833. 



PHYSICAL GEOGRAPHY. 



11. Spovting fountain of mineral water, discovered in 1832, near 

 Cape Uncino, kingdom of JVaples, by M. J. Aiddjo. — Bubbles of 

 of air were long since observed to rise trom the bottom of the water 



