401 F. Dellniann on Atmospheric Electricity. 



upon the rod c. In order that the collector may not be over- 

 thrown by high winds, the box carries at its lower edge a loop or 

 staple, through which, when necessaiy, a hasp, fixed to the rod 

 by a small wooden screw, can be passed. The carrier m is also 

 af copper \ of an inch thick and 1 foot long. Both carrier and 

 sphere are rendered as polished as possible, and the former is 

 rounded off at the bottom. 



In charging, the following method is adopted. The observer, 

 on removing the collecting sphere from its ti'ipod near the mea- 

 suring instrument, in the lower room to the left, carries it by 

 means of its box up stairs, steps through the open window / on 

 to the small balcony, places the box together with its sphere on 

 the top of the deal rod, returns within and draws up the rod by 

 means of a handle attached to the drum around which the rope 

 is coiled. As soon as the arm d strikes the ring b the rod 

 is fixed by means of the ratchet, the window g is opened, the 

 brass handle is seized, pulled, released, and finally the ratchet is 

 lifted so as to allow the rod to descend until a thick iron pin p, 

 passed through the rod, strikes against the ring of the iron bar 

 a, which now carries the rod until the following charge. In 

 order that the rod c may at its upper part possess the solidity 

 necessary for the pin p, it is surrounded as far as q with an iron 

 loop {BUchse) . The box bearing the sphere is now taken off the rod 

 and carried down stairs. There, near the measuring instrument, 

 stands the transferrer, a brass wire about 1 foot long and I line 

 thick, carefully rounded at the ends. It is fixed with a stick of 

 shell-lac to a firm wooden stand, by moving which, one end of the 

 transferrer is brought into contact with the sphere, and the other 

 with the conducting wire of the electrometer. The measuring 

 instrument thus becomes charged. The deflection being read off, 

 the nature of the electricity is ascertained by means of a plate 

 of cork, which having a shell-lac handle attached to it, is rubbed 

 on cloth and brought into the vicinity of the conducting wire. 



Above the window g in the figure, another loop r will be seen, 

 through which passes the conducting wire h ; its object is to 

 prevent the wire and rope from becoming entangled — to which 

 end, too, the wire and the rope are placed on opposite sides of 

 the rod. When the rod is drawn up, the loop r also holds the 

 handle i in one and the same position, so that it can be readily 

 found even in the dark. 



The rope passes over two rollers, only one of which can be seen 

 in the figure ; the other is placed on the same beam inside the 

 house; directly under the latter, near the window, is the drum 

 with its ratchet. 



The principal part of the whole apparatus is the sphere with its 

 carrier, to ensure the insulation of which the greatest care must 



