384 MisceUaneoiis Intelligence. 



5 hours 2 oz. more. It is not said how much the magnet would 

 carry, nor if the place where it lay when covered up and when 

 exposed to the sun were the same. 



23. New Electrical Battery. — Dr. Dana, of Harvard Uni- 

 versity in America, has constructed an electrical battery of 

 plates, extremely portable and compact, and from his experi- 

 ments, appearing to be very powerful. It consists of alternate 

 plates of flat glass and tin foil, the glass plates being on all sides 

 two inches larger than those of foil. The alternate plates of 

 tinfoil are connected together, i. e. the 1st, 3d, 5th, 7th. ^c. on 

 one side, and the other series, or 2nd, 4th, 6th, 8th, S^c. on the 

 other side, slips of tinfoil extending from the sheet to the edge 

 of the glass plates, for that purpose. These connexions 

 unite together all the surfaces, which when the battery is 

 charged, take by induction the same state. A battery con- 

 structed in this way, contains in the bulk of a 4to volume 

 a very powerful instrument, and when made of plate-glass, 

 it is extremely easy, by varnishing the edges, to keep the whole 

 of the inner surfaces from the air, and to retain it in a con- 

 stant state of dry insulation. 



From the superiority of mica over glass in the thinness of its 

 plates, its toughness, and flexibility, and its greater power of 

 insulation, there is every probability that an admirable instru- 

 ment might be constructed in this way with it. — Sillimans 

 Journal, I. p. 292. 



24. New Woolfe's Apparatus. — Dr. Hare, of the Univer- 

 sity of Pennsylvania, has contrived a new apparatus for the 

 impregnation of fluids by gasses, or for other purposes for 

 which Woolfe's apparatus is used. Its convenience consists in 

 being easily taken apart and put together, and, if required, of 

 being constructed in only two pieces, though with several 

 chambers. One part of the apparatus consists of several con- 

 centric glass jars, so proportioned in size as to admit of glass 

 receivers between them ; these are the various chambers for the 

 water or solution, and the inner ones are more convenient if 



