Mr. 0. J. Lodge. Experiments on [June 4, 



June 4, 1891. 

 Sir WILLIAM THOMSON, D.C.L., LL.D., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : 



I. "Experiments on the Discharge of Leyden Jars." By 

 OLIVER J. LODGE, F.R.S. Received May 2, 1891. 



EXPERIMENTS ON THE DISCHARGE OF LEYDEN JARS. 



The following experiments among others were made in the course 

 of 1888, beginning in February of that year. A brief account of the 

 early experiments, with some of the deductions from them, was given 

 in a couple of lectures to the Society of Arts in March, 1888, on 

 Lightning Conductors ; and in the ' Electrician,' vols. 21, 22, 23, under 

 the same title, a number of others were published at length, 

 viz., the series of experiments relating to "the alternative path." 

 But the rest of the experiments has never been published in any 

 detail ; though, as they led to some interesting observations con- 

 cerning electromagnetic waves, and incidentally measured the 

 velocity of transmission of a pulse along an isolated wire, they 

 ought to have been written out for publication long ago. 



I now venture to communicate them to the Royal Society, beginning 

 with such brief account of the earliest experiments as may suffice 

 to render the steps intelligible. 



Description of Jars Used. 



1. The pattern of jar ordinarily used was an open cylinder without 

 lid or neck, with the charging rod firmly supported from the interior 

 and quite free from the glass above the tinfoil. 



They were of two principal sizes, which I call for short "gallon" 

 and " pint." ^ 



Each gallon jar was 40 cm. high and 13 cm. diameter, coated to 

 within 10'5 cm. of the top ; and the capacity of the pair chiefly used 

 was 0*0062 microfarad each. Two in series had a capacity of 28 K 

 metres. Each pint jar was 16'5 cm. high and 8'2 cm. diameter, and 

 was coated to within 5 cm. of the top. The capacity of the one 

 chiefly used was O'OOIG microfarad. Two pint jars in series had a 

 capacity of 6'6 K metres. 



