380 



RECENT PROGRESS IN PHYSICS 



"because it does not present any new facts, but only opinions^ tlie cor- 

 rectness of which is still very problematical. 



Fijr. 16. Pi/> /-I 



§16. Observation of atmospheric elec- 

 tricity. — Romtrshausen has constructed 

 an apparatus lor observing atmospheric 

 electricity, the arrangement of which 

 is exhibited in fig. 16. (Pogg. Ann. 

 LXIX, 71.) 



Fig. 16 represents the application of 

 the collecting apparatus to any dwelling, 

 and to any story of it. 



H is the house, over the roof D of 

 which the collector can extend wathout 

 doing any injury. F is the window of 

 the observer's chamber; mn represents 

 the collecting rod in its general con- 

 struction. It rests above the window 

 in a strong iron socket m, and, by means 

 of a hoolr ?, is easily and firmly secured 

 in a slot k in the roof. It extends ob- 

 liquely from the house into the air, and 

 its details are arranged as follows : 



The rod of varnished pine wood, 10 

 or 12 feet long, is provided at i with a 

 brass band, in which the solid glass 

 rod h, \\ feet long, and coated with 

 shellac, is cemented. This supports, 

 at its upper end, the collecting appa- 

 ratus g n. 



For greater clearness, this part is shown in section 

 and on a larger scale in fig. 17. a e is a flat copper 

 ring, five inches in diameter, on the inside of which 

 are soldered collecting wires cl d of copper, gilded 

 and brought to a fine j)oint ; these are inclined out- 

 ward slightly, so as to appear like a crown. A cop- 

 per support, passing across the ring, and curved 

 somewhat downwards, bears on its underside the 

 socket g for fastening on the glass rod A, and on the 

 upper part a higher wire point is soldered. This 

 point is the most important part of the whole con- 

 trivance, since it alone, according to exact experi- 

 ment, renders sensible the slightest shades of atmos- 

 pheric electricity. 



