180 Miscellanies.. 



ferred to a method proposed by Professor Christie, ofWoolwich, sim- 

 ilar in principle, but differing in detail, and showed the needles for 

 applying this method. 



Prof. Bache further stated, that he had caused the method of heat- 

 ing these needles to the temperature of boiling water, to bring them to 

 a permanent magnetic condition, as proposed by Prof. Christie, to be 

 tried by Mr. Robinson. It had not proved successful. 



Mr. S. C. Walker made a verbal communication on the parallax of 

 the star, 61 Cygni, recently investigated by Mr. Bessel, and described 

 the nature of the researches by which this important point had been 

 established. 



March 15, 1839. — Professor Henry, of Princeton, made a verbal 

 communication relating to a phenomenon of capillary action which 

 had fallen under his notice. 



A lead tube, of about half an inch in diameter, and eight inches long, 

 happened to be left with one end immersed in a cup of mercury ; and 

 on inspection a few days afterwards, it was observed that the mercury 

 had disappeared from the cup, and was found on the floor at the other 

 end of the tube. Struck with the phenomenon, the cup was again 

 filled with mercury : the next morning the same effect was exhibited. 



The mercury had again passed over through the tube, apparently 

 like water through a capillary siphon, and was again found on the 

 floor. 



On cutting the tube into pieces, it was evident that the mercury had 

 not passed along the hollow axis, but had, apparently, been transmit- 

 ted through the pores of the solid metal. To determine this, a lead 

 rod about seven inches long and a quarter of an inch in diameter, was 

 bent into the form of a siphon. The shorter leg was immersed in a 

 watch-glass filled with mercury, and a similar glass placed under the 

 end of the longer leg, to receive the metal which might pass over. 

 At the end of twenty-four hours, a globule of mercury was perceived 

 at the lower end ; and in the course of five or six days all the mercury 

 passed over, leaving a crop of beautiful arborescent crystals, of an 

 amalgam of lead, in the upper glass. 



The mercury did not pass along the surface of the wire, since the 

 lead exhibited, externally, but little change of appearance ; although 

 the progress of the penetration could be traced by a slight variation 

 of the color of the oxide on the surface. 



The action is much influenced by the texture of the lead. When a 

 rod of cast lead, of the same size and form, was substituted for the 

 one before described, the globule of mercury did not make its ap- 

 pearance at the lower end until about forty days ; and all the mercury 

 of the upper glass had not yet (after three months ) entirely disap- 

 peared. 



