500 Prof. Fleming and Mr. Clinton on the 



Table I. — Measurement of the Capacity of Flat Iron Strips 

 suspended in a large room, taken separately and together, 

 at various distances apart. 



dumber of 

 strips taken 

 in parallel. 



Measured Total Electrical Capacity with 

 distance between strips as below stated. 



Sum of the 



separate 

 individual 

 capacities. 



12-in. 6-in. 



3-in. 



Close 

 together. 



1 



•7 



3 ".'.... ...... 



4 



5 



6 



1-00 1-00 

 1-74 145 

 2-31 1-80 

 2-79 2-10 

 3-28 2-42 

 3-75 270 

 4-18 2-98 

 461 3-25 

 5-03 3-51 

 5-46 3-76 

 5-90 4-00 



100 

 1-34 

 1-61 

 1-85 

 2-03 

 221 

 2-36 

 2-52 

 2-68 

 2-82 

 297 



TOO 

 119 

 1-27 

 1-44 

 T46 

 1-54 

 1-59 

 1-72 

 1-81 

 1-96 

 1-99 



1-0 

 20 



3-0 

 4-0 

 5-0 

 6-0 

 7-0 

 80 

 9-0 

 100 

 11-0 



8 



9 



j 10 



11 



parallel is very nearly proportional to the square root of the 

 number of strips : thus, four strips have only twice the 

 capacity of one strip, and nine strips rather more than three 

 times the capacity of one strip. The same fact has been 

 observed by us in the case of the measurements of the 

 capacity of wires suspended in the open air. Taking for 

 convenience as a unit of small capacity the micro-microfarad 

 (M.M.Fd.), i. *?., the millionth part of one microfarad, we 

 have made measurements of the capacity of nearly vertical 

 insulated wires suspended in the air, with their lower ends a 

 few feet from the ground, and have obtained the following- 

 results. In these measurements the capacity measured was 

 that of the wire or body under investigation, together with 

 that of a connecting wire, and that of the commutator 

 itself. This latter quantity is about 60 micro-microfarads, 

 and that of the commutator and lead used varied from 80 

 to 300 M.M.Fd., according to the length of lead. This 

 value is subtracted from the observed total value. The 

 capacity of a wire one-tenth of an inch in diameter and 111 

 feet long, with the bottom end about 5 feet from the ground, 

 was found to be 205 micro-microfarads. In the next place, 

 160 w T ires of the same kind and diameter, but 100 feet long, 

 were arranged in a conical form, so that the common junction 

 of all the wires was about 10 feet from the ground, and the 

 tops of all the wires were distributed around a square of 

 80 feet side, and at a height of about 112 feet from the 

 ground, the wires being therefore about 2 feet apart at the 



