To Peter Collinson
Copy: New-York Historical Society2
April 18th. 1754
Since September last, having been abroad on two long Journeys,3 and otherwise much engag’d, I have made but few Observations on the positive and negative State of Electricity in the Clouds. But Mr. Kinnersley kept his Rod and Bells in good Order, and has made many. Once this Winter the Bells rang a long time during a fall of Snow, tho’ no Thunder was heard nor Lightning seen. Sometimes the Flashes and Cracks of the Electric Matter between Bell and Bell were so large and loud, as to be heard all over the House: But by all his Observations the Clouds were constantly in a negative State, till about Six Weeks ago, when he found them once to Change in a few Minutes from the negative to the positive. About a fortnight after that, he made another Observation of the same kind: And last Monday afternoon, the Wind blowing hard at S.E. and veering round to N.E. with many thick driving Clouds, there were 5 or 6. successive changes from negative to positive, and from positive to negative the Bells stopping a minute or two between every Change. Beside the Methods mentioned in my Paper of September last, of discovering the electrical State of the Clouds,4 the following may be used: When your Bells are ringing, pass a rubb’d Tube by the Edge of the Bell connected with your Pointed Rod: If the Cloud is then in a negative State, the Ringing will stop; if in a positive State it will continue, and perhaps be quicker. Or suspend a very small Cork Ball by a fine Silk Thread, so that it may hang close to the Edge of the Rod-Bell: Then whenever the Bell is electrified, whether positively or negatively the little Ball will be repell’d, and continue at some distance from the Bell. Have ready a round-headed Glass Stopper of a Decanter, rubb it on your side till it is electrified, then present it to the Cork Ball. If the Electricity in the Ball is positive it will be repell’d from the Glass Stopper as well as from the Bell. If negative it will flye to the Stopper. These are Mr. Kinnersley’s Methods.5
2. Printed in Exper. and Obser., 1760, pp. 128–9.
3. The journeys were to Carlisle to treat with the Indians, Sept. 26–Oct. 4, 1753 (see above, p. 64), and to Maryland on post office business in January (see above, p. 186).
4. See above, p. 69.
5. The last sentence is omitted from the 1760 and later editions of Exper. and Obser.