228 journal of Experiments, 30 Dec, 1771 



double touching wire was removed and a single one used in its room, which was 

 sometimes fastened to the middle of the glass tube, and sometimes used without 

 it, as will be expressed. 



The height of the top of the circles above floor = 4'. 3". 



The center of the large circle when that was used, or the middle point 



(of i(\" 

 / // 



/ " -J 



from l vial ^ 



(middle of trial plate) ' 



The circles were suspended by silk strings. The length of the touching wires 

 for the circles was 36 inches. 



473] Monday Dec. 30 [1771]. Th. 50. S. H. 18. 

 Two small circles at 18 inches from each other. 



Equivalent diff. J sum Proportion 



B S scp. about T V 13-821 



3-47 12-08 i-ooo 

 C - -2\ do. 10-35} 



The same at 26 inches distance. 



C 4 do. 11-07) 



B-6J do. 14-51} 3 ' 44 I2 ' 79 I ' 59 



at 36 distance. 



C - 4^ do. 11-31 



B - \ do. 11-37 4'8 13-38 1-108 



A 14^ do. 15-42 

 Large circle, touching wire being fastened to glass tube. 



A - 17* do. 16-04 



B- 3 do. 12-85 4 ' 9 I4 ' 89 I-233 

 Do. without glass. 



B - 3 12-85 



4-00 14-80 1-233 

 A - 17^ 16-94 



The Proportions by theory, vide P. 14 of calculations*, are as follows f. 



Calculation Experiment 



.Small circles at 18 i-ooo i-ooo 



at 26 1-044 I '59 



at 36 1-074 1-108 



single plate 1-160 1-233 



474] The same experiments repeated in the same manner except that the 

 distance of the center of the large circle, or of the middle point between the 



* ["P. 14 of Calculations" refers to a rough calculation in parcel No. 6, which 

 is an early form of Props. XXIX and XXX. See Arts. 140-143. "P. 14" contains 

 the following remark, which fixes its date after Art. 456, "By exp. P. 15 [Art. 456] 

 quant, el. in circle is to that in globe of same diam. as i : 1-56 :: : -78, therefore 



= -78." Here n is the reciprocal of p in Art. 140.! 

 2 + 2W 



f [See Art. 68 1 and Notes u and 21.] 





