ATMOSPHERIC ELECTRICITY. 1 27 



well as the whole plain of Piedmont is easily discovered. It 

 consisted of an iron wire one hundred and thirty two French 

 feet long, extending from a stack of chimnics, over which it 

 was raised by a long pole to the top of a cherry tree. Its extre- 

 mities were insulated and defended by a small umbrella of tin, 

 covered beneath with sealing wax. From this wire, another was 

 introduced into a room through a pane of glass. It was found 



1. That the electricity, during serene weather, in its ordinary P»th balls were 

 ,,.-.,-,. .. ... * connected with 



or mean state,causes two balls of pith of elder one line inaiameter, t ^ e wirc 



to diverge six lines from a small plate of metal placed between The electricity 

 them. The balls were suspended by very fine treads, sixteen lines stant i y positive 

 long. 2. In the state of its greatest intensity the divergence of in clear wea- 

 the balls is fifteen, twenty, or moie degrees from the metal. Tt 

 3. In its weakest state the balls move towards a conductor at a 

 very small distance. 4. The electricity is sometimes so slow in 

 its accumulation as to require one minute to become again sensi- 

 ble, after having been taken off by touching the wire j but at 

 other times it became again sensible in the time of one second. 

 5. That it is always of the positive kind, excepting in some 

 very rare instances, when the contrary happens,in consequence of 

 the wind blowing from some other part of the sky which is not 

 serene. The instances related by Beccariaare very curious. 



Father Beccaria used an hygrometer consisting of a string of He used an 1 

 thirty-two flaxen threads twisted together to the thickness of flaxen^nread 

 two thirds of a line. It was twelve feet long, and the lower and another of 

 part passed round a pully which carried an index. The stretch- oat eai ' 

 weight was two pounds. Such an hygrometer commonly 

 served him a year, and he distinguished smaller mutations than 

 it was capable of shewing by means of another hygrometer 

 made of a twisted rye-stalk. 



6. During clear weather the moisture in the air is the con- T lie electr,cIt T 

 i t- i i • i • . i i • , ,n dear wea- 



stant conductor of the atmospheric electricity ; and this elec- t h er is proper* 



tricity, is proportioned to the quantity of that moisture which tinned to the 



surrounds the wire, except such moisture lessens the insulation * m '° y " 



both of the wire and of the atmosphere. 



Beccaria observes, that he does not here pretend to point the 



. ciuse or principle which produces the electricity, but only to 



ascertain the medium in which it is inherent, and to the quantity 



of which it is generally proportioned. 



f. Th3 



