78 Intelligence and Miscellaneous Articles. 



sensible activity varies in that ratio. As they approach the point of 

 liquefaction, other considerations derived from the special atomic 

 constitutions of the media must be introduced., The entire absence 

 of a limit to the division of parts would produce that homogeneous- 

 ness from which Mariotte's law becomes an inevitable inference. 

 Such an inference, as applied to media in general, being- contrary to 

 the fact, a limit to actual division of parts must be admitted. Any 

 other theory than one of ultimate molecules, separated by spaces, seems 

 to impose inferences conflicting with facts, throwing us back irresisti- 

 bly into the theory of true molecular structure. — Silliman's American 

 Journal, May, 1850. 



Boston, April, 1850. 



EFFECTS OF ATMOSPHERIC ELECTRICITY UPON THE WIRES OF 

 THE MAGNETIC TELEGRAPH. 



The Revue Scientiflgue for December last contains an interesting 

 article by M. Baumgartner on the subject of the effects of atmo- 

 spheric electricity upon the wires of the magnetic telegraph. The 

 following are the most interesting of his results : — 



1 . The needle rarely coincides with the point which is determined 

 by its astatic state and the tension of its suspension thread ; almost 

 always it deviates more or less from this point, which proves that 

 it is influenced by an electric current. i 



2. The variations are of two kinds ; there are some which reach 

 50°, others extend over \° or 8'. The first are less frequent; they 

 differ so often in direction and intensity that it is impossible to de- 

 duce a law for them. On the contrary, the small deviations appear 

 connected by a very simple law. 



The observations made at Vienna and at Gratz appear to show 

 that, during the day, the electric currents move from Vienna and 

 from Gratz to Semmering, which is more elevated. This direction 

 is inverse during the night. It appears that this change of direction 

 takes place after the rising and setting of the sun. 



3. The regular current is less disturbed by the irregular currents 

 when the air is dry and the sky is serene, than when the weather is rainy. 



4. In general, the current is more intense with short than with 

 very long conductors; often, even, the current of the longer chain 

 is opposed to the current of the shorter chain. 



Where there is a difference of intensity, this difference is far 

 greater than that which could originate from the resistance of the 

 longer conductor. 



When the sky is cloudy and the weather stormy, there are fre- 

 quently observed in the electric conductor currents which are suffi- 

 ciently intense to affect the telegraphic indicators, which are, how- 

 ever, far from having extreme sensitiveness. 



When they were placing the conducting wires of the Northern 

 Telegraph line from Vienna, the workmen frequently complained of 

 a kind of spasms which they felt in handling the wires. These 

 spasms ceased as soon as they took the precaution not to touch the 

 wires with naked hands. These spasms were most frequent and in- 

 tense in Styria, the highest region of the line. Thus, near Kranich- 

 feld, a workman received a shock sufficiently violent to overturn him 

 and paralyse his right arm. 



